Tuning Converting Co2-Revolver to PCP

Hi guys,

I just wanted to show a little project I did over the holidays: converting a Co2-Revolver to HPA/PCP.

As base I used a Gamo PR-776 Co2 Revolver in .177 (it’s quite a standard revolver, you can find under many labels and names). It`s one of the „typical“ 100-bucks-Revolvers, so nothing too great.

As powersource I currently use approx. 1050 psi of pressure, coming from a 26cui regulated HPA-paintballtank.

That results in pretty consistent 295 fps with a variety of just +- 8fps (you always lose fps compared to using Co2). Also, the choice of pellets seems to make a big difference in fps and energy. 8 grain pellets go up to 310 fps. I actually use 7,87 grain pellets (the Gamo has a rifled barrel). I get like 2,2 joule / 1,6 ft/lbf of energy. As I am shooting on 10 yards in my basement, this is just right. Making pretty clean holes for a airgun, but not using much gas or putting too much pressure on the system.

I still need to adjust the sights (the Gamo shooting pretty high, so I need to work a bit on that, because I actually have to aim under the target, without having a single point to aim). Still I am pretty happy with the results so far, for testing (standing free, holding with both hands). The four pellets in the hole to the right are within 5/8”.

The gauge on the paintball tank didn’t go down noticeably, even though I was testing for more than 120 shots. I think u can easily do 1000+ shots with one filling of the tank to 3000 psi. Saving a lot of Co2 and money of course. If you are interested in a longtime review, just let me know.

Best regards form Europe

20240107_194926.jpg
 
The most important part is surely the "Co2 to hpa converter" (you can easily find it by googling) you can see on this picture here. It's the golden part in the grip of the revolver, that replaces the co2 cartridge and stays in the gun permanently.

But there are some minor things I needed to take care of, alltough noting too complicated. I hope I can do a bit of an explanation within the next few days and also review a bit on pressure, safety issues, pros and cons and so on.

20240104_193104.jpg
 
  • Like
Reactions: nobody1 and Loff
Whoops, became a bit longer than planned :eek: But still: That's all I got to say by now ;)

Disclaimer
First of all: This is not a tutorial or an instruction. It’s simply a presentation how I did it. So I am not recommending converting a gun or anything else. What you do and don’t is your own responsibility. Only thing I recommend: Be careful when handling pressured objects, they can get pretty dangerous and hurt you.


1. Basics

Base: The gun

As base I used a Gamo PR-776 Co2 Revolver in .177 (it’s quite a standard revolver, you can find under many labels and names). It`s one of the „typical“ 100-bucks-Revolvers, so nothing too great, but it has a rifled barrel.

The heart of the project: The “co2 to hpa converter”

1704784222950.jpeg

You can find these all over the internet and purchase them for 15 – 20 bucks. I assume they all come from the same one or two factorys in China, as I ordered several and didn’t find any differences. What you get is a pretty well made metal cylinder (empty on the inside) and a filling-adapter with a thread. The thread wont go into the adapter (pictures are a bit misleading there), only the tip goes into the cylinder (there’s a sealing ring on the inside).


HpaAdapter.jpg

Cylinder. First thing you notice: The cylinder is a look-alike of a co2-cartridge – as long as you try to put it in your gun. Then you will see, that there’s a small but important difference. The co2-cartdridge is rounded, while the lower end of the cylinder isn’t. It ends in a “corner”. So it can be difficult to fit it in the magazine of some airguns. In my case it was necessary to adjust it. I saw a picture of somebody, starting to adjust the magazine and take of material of the backend of the adapter. Not a good idea, because it’s way more simple to adjust the “bottleneck”, so the upper end, of the adapter. I just took some sandingpaper and filed away maybe 1mm. Then the adapter fitted into the magazine. It still need’s a little bit of room, so it can be pressed against the valve. It is made of aluminum, so it is quite easy and there’s plenty of material. In my project it was necessary to put on an additional o-ring on the top of my adapter, so it connected to the valve without pressure loss sideways. Here’s a picture of the cylinder next to the magazine of a Umarex P08 and fitted in (gonna be my next conversion I think, as I want to try converting a BB gun as well).

Filling adapter. There are two different threads that can be ordered. A smaller one ¼-20 and a wider one m12*1. A lot of airguns have one type or the other. It’s initially used for a screw, that presses your co2-cartridge against the valve, to open it and power your gun. This screw has to be removed (should be easy, as it’s a part for maintance and can be replaced) and replaced by the filling adapter. If none of this two is fitting, I personally would order the smaller ¼-20 and a screw tap. But I never tried this actually.

I then used a pipe wrench to screw in the filling adapter into the cylinder using very little force. I just screwed it in by hand and then used the pipe wrench for another 1/4 to 1/3 turn.

20240108_195637.jpg


After that, I adjusted the grips of the revolver by drilling a 15mm hole in them for the adapter. That's it


2. Adjusting Pressure

Here comes the power – how much psi can my airgun safely take?

I bought an ordinary paintball hpa tank with a regulator set to 850 psi. Why 850 psi? Because that’s the number you usually find about the pressure in a co2-cartride. I plugged it in, turned up the pressure and fired a shot through my chrony. 60m/s = 195 fps. Uff. Disappointing. Quite low. I tried shooting it, worked ok on 5-6 yards. But with longer distances, the shots dropped an the holes in the target where becoming worse. I was a bit confused, to be honest. 850 psi are 850 psi, doesn’t matter if they come from co2 or pressured air? Right? Nonpe. Because: Not only the pressure itself matters, also the time it is applied. How long the 850 psi are accelerating your pellet to fire it out of your barrel. And here is a big difference between co2 and pressured air. If you compare it to the weather:
Pressured air is like a lighting, like a flash. It’s BAM, there and gone the same second. So there is a very very limited amount of time, it can accelerate your pellet.

Co2 is more like thunder, its building up, like VROOOOM. It’s a liquid in the co2-cartridge and becoming a gas when expanding and therefor applying pressure to your pellet. This process needs time, time for your pellet to reach speed.

So I thought: Ok, there are two ways to cope with this. Either increase the amount of time, the valve is opened and the pressured air can apply pressure. Changing hammer and valve spring and stuff like that. But Co2-Pistols normally already got a pretty stiff hammer spring. I gave it a bit of more compression, but it didn’t make any difference.

So I decided to apply more pressure. But isn’t it very dangerous, applying more pressure than the 850 psi? Won’t more pressure turn your gun into a shrapnel? Well yes, pressure is dangerous. Especially high pressure can cause enormous damage, because a lot of air is exhausting in a single moment. And again: I am not recommending doing anything with your gun, converting, modding, and so on. But I felt pretty safe (although being the nervous type) turning up the pressure a bit, because of two reasons:

First one: Pressure is dangerous because a lot of air is saving a lot of energy. Inside your co2 gun you have nearly no volume or capacity for storing air. The pressured air is in the HPA tank. If the tank explodes: Yes, things get very naughty. But inside your gun there is nearly no volume. Nearly no volume means very little of air. And very little of air means very little of energy, even though it is highly pressured.

Second one: I think my gun can easily take the applied pressure, because generally we are mischarging the 850 psi in the co2-cartridges. Because it isn’t 850 psi all the time. It depends on the temperature. If u shoot your co2 gun on a hot day (and I did that, not knowing it), lets say 90F (or 32 Celsius), the pressure is on 1400 PSI. The manual of the gamo revolver I was using says: Don’t operate the gun beyond 50 Grad Celsius (122 Fahrenheit). On 122 F a full Co2-Cartride got 1800 PSI… I have seen a video, someone using a “rechargeable Co2-Cartride”, that should be powered up with a high-pressure pump. He pumped it up to 3000 (!) PSI and packed it into his gun. Nothing happened. Really “nothing”. It didn’t shoot, because the hammer spring wasn’t strong enough to open the valve against the 3000 PSI. Then he packed it into a cheaper airgun and it did fire quite normally…

So I used my yong heng compressors gauge to check the pressure I need. This way I found out, that the gun will do 90ms / 295 fps on 1050PSI. The same pressure a Co2-Cartride got reaching 85 F or (29 Celsius). Think about a cosy 75 F day in the garden and the sun is shining on your black Co2-Airgun and the black polymer grips. It reaches 85F within minutes. Btw: I tested 1350 PSI as well. Result: Gun didn’t fire (hammer spring wasn’t strong enough to open the valve?) A bit of pressure evaded sideways. Nothing else happened.

Co2_pressure_vs_fill_phases.jpg

That of course doesn’t mean it’s absolutely safe. But in my opinion: If there’s a critical failure, I know from my other PCP-guns, it will hit the weakest part. And that means the valve or bust out an o-ring (it did while testing higher pressures). So normally, the gun will just lose air trough the barrel till empty. Still I was very careful and especially wore eye protection.

I adjusted the shims in the hpa-tank regulator to 1050 PSI, reaching the desired speed. That results in pretty consistent 295 fps with a variety of just +- 8fps.

Now for a kind of summary:


3. Summary – the cros and the cons

Let´s start with the downsides. There certainly are some (as far as I see from my limited experience):

*A bit loss of power. Gun fires approx. 20 % weaker. For plinking on cans and stuff like that, that’s a setback.

*Your gun gets a bit heavier. Not much, but its noticeable, especially because of the weight of the pressure hoses.

*Louder. The gun is firing louder than on co2. Could be an issue in an apartment with neighbors, family, …

*Money. Converting a single gun costs 15 – 20 bucks. A standard hose normally used for paintball approx. another 20 bucks. I made a mistake in the first place, not ordering one with a slide check. So I have to get the pressure out of the hose before I can disconnect the gun (initially, I thought this is gonna take 4 or 5 “empty” shots when the hpa tank is closed. Nope. It takes like 40 or 50). The hpa tank itself with the 850 PSI regulator was 50 bucks. Then I counted in another 5 bucks for stuff (o-rings, the washers/sims to adjust the hpa regulator, silicon spray, stuff like that). I needed another pressure hose, the spring supported type as strain relief. Otherwise the flexible hose will pull your gun to the side a bit. I also needed a backpack, because I don’t want to carry the tank in hand of course. I ordered a bottle holder (normally for cyclists), that I will attach to my belt, another 5 bucks.

The bigger issue is getting the pressured air into your home. I already own a compressor and a big 610 cui compressed air cylinder, so it’s not that much of a problem. This is my yong heng setup I use for my other pcp guns. If somebody lives near a diving shop, firefighters, paintball area, it’s also easy to get pressured air.
View attachment 20231227_163810.jpg

*The system limits you to one magazine. So changing to a new magazine after firing out the first one is impossible – doesn’t matter for revolvers or other models, where co2 tanks and magazine are separated of course.

*No ”quickdraw”-drills or fancy dynamic stuff. The hose is in the way, so its not possible to do draw and quickfire drills or stuff like that.


Now the sunny side up:

*Consistency and accuracy. The regulator on the hpa tank is working much more exactly than the gun itself. The gun gains consistency in the shots and therefore accuracy (especially in the x-axis, so the up and down).

*Flexibility. I found it annoying using co2, that you have to fire out the cartridge. Or sometimes you’re in doubt, if u want another cartridge in, so you have to go “all the way”, even though your maybe just in the mood for another 20 shots. Now I can just connect or disconnect whenever I like.

*Money and efficiency. Depending on how many co2-cartridges / year shot and the investments necessary, it can pay off quite fast. If you count 60 shots on a co2-cartridge that cost’s 30 cents, your on 0,5 cent a shot for the energy.
I didn’t test it out, but according to the gauge on the hpa tank, I am using very little gas for shooting. So the 26 cui tank filled up to 3000 psi should be enough for approx. 1000+ shots (I think its way more, but I don’t want to get too optimistic). I could refill this with my compressor or, for better comparability, out of my big 610 cui compressed air cylinder 25 times. That’s 25.000 shots. Refilling the big cylinder in a diving shop nearby normally costs me 5 bucks as a tip. So let’s say 500 cents for 25.000 shots. That would be 0,02 Cent a shot. If I fill it up with my compressor myself it should be even cheaper.

*No cooldown effect. Fire at will.

*Can be dismounted – converting back to co2 is done within minutes.

As a final verdict I guess: As I am already a pcp shooter and got all the stuff needed anyway, it was just a matter of 50 bucks and a bit of time. Still it only made sense, because I am having fun in doing stuff like this and I know, it gonna pay off quite soon. Next try is converting a bb blowback umarex p08, the cylinder should arrive within the next days. Maybe the blowback system changes things? Or the lighter bbs need less psi? We will see 😊

20240102_183744.jpg
 
Last edited:
  • Like
Reactions: nobody1 and Loff
Before actually reading your post, based on its title I thought, "Oh brother, another airgunner demonstrating Darwin's theory" (survival of the fittest, and vice-versa). However I was pleasantly surprised to see your approach to converting a Co2 gun to PCP well pre-meditated, brilliantly executed, and perfectly SAFE.

That said, thought I'd get that out there before anyone reacts badly to the title, without reading your post.

Good show, J; excellent thread! (y)

AAP new cover small.jpg


BTW, the custom(ized) 9mm Crosman 2250 cover-photo pistol being converted to bulk-fill, it was capable of being run on Co2 or high-pressure air. Knowing the relatively small chamber would return very few consistent shots I never ran it on air. But had I, would have kept it under 1500 PSI/100 BAR.

For entertainment value only, I'm attaching a pertinent chapter from my book Airgun Chronicles- Thirty Years Of Airgun Testing And Competition (now out of print); the chapter titled A PCP And Co2 Primer.

View attachment PCP and Co2 chapter pdf.pdf
 
Last edited:
  • Like
Reactions: Jarnold
Hi @AirNGasman Thank you very much for your friendly reply and espcially for that excellent piece of information in the pdf. Congratulations on that. Read it right away. Funny thing ist: it contains a lot of the informations and the facts I was looking up one by one on the internet for my project.

I was also thinking about tuning the springs as you mention it. But I didnt want to make the hammer spring any stronger, because, as we said, its already capable to work on 1000psi+. Making it stronger would surely increase fps without increasing pressure, but the whole gun is made of rather cheap and soft metal, so I was a bit worried about "hammering" out the valve shot per shot. I saw pictures on a german forum of a ruined valve/gun because of a "tuning kit for the hammer spring" :confused:

BTW, the custom(ized) 9mm Crosman 2250 cover-photo pistol being converted to bulk-fill, it was capable of being run on Co2 or high-pressure air. Knowing the relatively small chamber would return very few consistent shots I never ran it on air. But had I, would have kept it under 1500 PSI/100 BAR.
The 2250 looks awesome. I think your definitly right. And 1500 PSI would maybe be the absolute max I would be willing to go on a decent build co2 gun. Still: Sometimes the co2 and the pcp version of one and the same type of gun are very similar, so the different "working pressures" should have mor overlaps than commenly known.

Best regards from Austria :)
 
Whoops, became a bit longer than planned :eek: But still: That's all I got to say by now ;)

Disclaimer
First of all: This is not a tutorial or an instruction. It’s simply a presentation how I did it. So I am not recommending converting a gun or anything else. What you do and don’t is your own responsibility. Only thing I recommend: Be careful when handling pressured objects, they can get pretty dangerous and hurt you.


1. Basics

Base: The gun

As base I used a Gamo PR-776 Co2 Revolver in .177 (it’s quite a standard revolver, you can find under many labels and names). It`s one of the „typical“ 100-bucks-Revolvers, so nothing too great, but it has a rifled barrel.

The heart of the project: The “co2 to hpa converter”

View attachment 423573

You can find these all over the internet and purchase them for 15 – 20 bucks. I assume they all come from the same one or two factorys in China, as I ordered several and didn’t find any differences. What you get is a pretty well made metal cylinder (empty on the inside) and a filling-adapter with a thread. The thread wont go into the adapter (pictures are a bit misleading there), only the tip goes into the cylinder (there’s a sealing ring on the inside).


View attachment 423575
Cylinder. First thing you notice: The cylinder is a look-alike of a co2-cartridge – as long as you try to put it in your gun. Then you will see, that there’s a small but important difference. The co2-cartdridge is rounded, while the lower end of the cylinder isn’t. It ends in a “corner”. So it can be difficult to fit it in the magazine of some airguns. In my case it was necessary to adjust it. I saw a picture of somebody, starting to adjust the magazine and take of material of the backend of the adapter. Not a good idea, because it’s way more simple to adjust the “bottleneck”, so the upper end, of the adapter. I just took some sandingpaper and filed away maybe 1mm. Then the adapter fitted into the magazine. It still need’s a little bit of room, so it can be pressed against the valve. It is made of aluminum, so it is quite easy and there’s plenty of material. In my project it was necessary to put on an additional o-ring on the top of my adapter, so it connected to the valve without pressure loss sideways. Here’s a picture of the cylinder next to the magazine of a Umarex P08 and fitted in (gonna be my next conversion I think, as I want to try converting a BB gun as well).

Filling adapter. There are two different threads that can be ordered. A smaller one ¼-20 and a wider one m12*1. A lot of airguns have one type or the other. It’s initially used for a screw, that presses your co2-cartridge against the valve, to open it and power your gun. This screw has to be removed (should be easy, as it’s a part for maintance and can be replaced) and replaced by the filling adapter. If none of this two is fitting, I personally would order the smaller ¼-20 and a screw tap. But I never tried this actually.

I then used a pipe wrench to screw in the filling adapter into the cylinder using very little force. I just screwed it in by hand and then used the pipe wrench for another 1/4 to 1/3 turn.

View attachment 423576

After that, I adjusted the grips of the revolver by drilling a 15mm hole in them for the adapter. That's it


2. Adjusting Pressure

Here comes the power – how much psi can my airgun safely take?

I bought an ordinary paintball hpa tank with a regulator set to 850 psi. Why 850 psi? Because that’s the number you usually find about the pressure in a co2-cartride. I plugged it in, turned up the pressure and fired a shot through my chrony. 60m/s = 195 fps. Uff. Disappointing. Quite low. I tried shooting it, worked ok on 5-6 yards. But with longer distances, the shots dropped an the holes in the target where becoming worse. I was a bit confused, to be honest. 850 psi are 850 psi, doesn’t matter if they come from co2 or pressured air? Right? Nonpe. Because: Not only the pressure itself matters, also the time it is applied. How long the 850 psi are accelerating your pellet to fire it out of your barrel. And here is a big difference between co2 and pressured air. If you compare it to the weather:
Pressured air is like a lighting, like a flash. It’s BAM, there and gone the same second. So there is a very very limited amount of time, it can accelerate your pellet.

Co2 is more like thunder, its building up, like VROOOOM. It’s a liquid in the co2-cartridge and becoming a gas when expanding and therefor applying pressure to your pellet. This process needs time, time for your pellet to reach speed.

So I thought: Ok, there are two ways to cope with this. Either increase the amount of time, the valve is opened and the pressured air can apply pressure. Changing hammer and valve spring and stuff like that. But Co2-Pistols normally already got a pretty stiff hammer spring. I gave it a bit of more compression, but it didn’t make any difference.

So I decided to apply more pressure. But isn’t it very dangerous, applying more pressure than the 850 psi? Won’t more pressure turn your gun into a shrapnel? Well yes, pressure is dangerous. Especially high pressure can cause enormous damage, because a lot of air is exhausting in a single moment. And again: I am not recommending doing anything with your gun, converting, modding, and so on. But I felt pretty safe (although being the nervous type) turning up the pressure a bit, because of two reasons:

First one: Pressure is dangerous because a lot of air is saving a lot of energy. Inside your co2 gun you have nearly no volume or capacity for storing air. The pressured air is in the HPA tank. If the tank explodes: Yes, things get very naughty. But inside your gun there is nearly no volume. Nearly no volume means very little of air. And very little of air means very little of energy, even though it is highly pressured.

Second one: I think my gun can easily take the applied pressure, because generally we are mischarging the 850 psi in the co2-cartridges. Because it isn’t 850 psi all the time. It depends on the temperature. If u shoot your co2 gun on a hot day (and I did that, not knowing it), lets say 90F (or 32 Celsius), the pressure is on 1400 PSI. The manual of the gamo revolver I was using says: Don’t operate the gun beyond 50 Grad Celsius (122 Fahrenheit). On 122 F a full Co2-Cartride got 1800 PSI… I have seen a video, someone using a “rechargeable Co2-Cartride”, that should be powered up with a high-pressure pump. He pumped it up to 3000 (!) PSI and packed it into his gun. Nothing happened. Really “nothing”. It didn’t shoot, because the hammer spring wasn’t strong enough to open the valve against the 3000 PSI. Then he packed it into a cheaper airgun and it did fire quite normally…

So I used my yong heng compressors gauge to check the pressure I need. This way I found out, that the gun will do 90ms / 295 fps on 1050PSI. The same pressure a Co2-Cartride got reaching 85 F or (29 Celsius). Think about a cosy 75 F day in the garden and the sun is shining on your black Co2-Airgun and the black polymer grips. It reaches 85F within minutes. Btw: I tested 1350 PSI as well. Result: Gun didn’t fire (hammer spring wasn’t strong enough to open the valve?) A bit of pressure evaded sideways. Nothing else happened.

Co2_pressure_vs_fill_phases.jpg

That of course doesn’t mean it’s absolutely safe. But in my opinion: If there’s a critical failure, I know from my other PCP-guns, it will hit the weakest part. And that means the valve or bust out an o-ring (it did while testing higher pressures). So normally, the gun will just lose air trough the barrel till empty. Still I was very careful and especially wore eye protection.

I adjusted the shims in the hpa-tank regulator to 1050 PSI, reaching the desired speed. That results in pretty consistent 295 fps with a variety of just +- 8fps.

Now for a kind of summary:


3. Summary – the cros and the cons

Let´s start with the downsides. There certainly are some (as far as I see from my limited experience):

*A bit loss of power. Gun fires approx. 20 % weaker. For plinking on cans and stuff like that, that’s a setback.

*Your gun gets a bit heavier. Not much, but its noticeable, especially because of the weight of the pressure hoses.

*Louder. The gun is firing louder than on co2. Could be an issue in an apartment with neighbors, family, …

*Money. Converting a single gun costs 15 – 20 bucks. A standard hose normally used for paintball approx. another 20 bucks. I made a mistake in the first place, not ordering one with a slide check. So I have to get the pressure out of the hose before I can disconnect the gun (initially, I thought this is gonna take 4 or 5 “empty” shots when the hpa tank is closed. Nope. It takes like 40 or 50). The hpa tank itself with the 850 PSI regulator was 50 bucks. Then I counted in another 5 bucks for stuff (o-rings, the washers/sims to adjust the hpa regulator, silicon spray, stuff like that). I needed another pressure hose, the spring supported type as strain relief. Otherwise the flexible hose will pull your gun to the side a bit. I also needed a backpack, because I don’t want to carry the tank in hand of course. I ordered a bottle holder (normally for cyclists), that I will attach to my belt, another 5 bucks.

The bigger issue is getting the pressured air into your home. I already own a compressor and a big 610 cui compressed air cylinder, so it’s not that much of a problem. This is my yong heng setup I use for my other pcp guns. If somebody lives near a diving shop, firefighters, paintball area, it’s also easy to get pressured air.
View attachment 423579

*The system limits you to one magazine. So changing to a new magazine after firing out the first one is impossible – doesn’t matter for revolvers or other models, where co2 tanks and magazine are separated of course.

*No ”quickdraw”-drills or fancy dynamic stuff. The hose is in the way, so its not possible to do draw and quickfire drills or stuff like that.


Now the sunny side up:

*Consistency and accuracy. The regulator on the hpa tank is working much more exactly than the gun itself. The gun gains consistency in the shots and therefore accuracy (especially in the x-axis, so the up and down).

*Flexibility. I found it annoying using co2, that you have to fire out the cartridge. Or sometimes you’re in doubt, if u want another cartridge in, so you have to go “all the way”, even though your maybe just in the mood for another 20 shots. Now I can just connect or disconnect whenever I like.

*Money and efficiency. Depending on how many co2-cartridges / year shot and the investments necessary, it can pay off quite fast. If you count 60 shots on a co2-cartridge that cost’s 30 cents, your on 0,5 cent a shot for the energy.
I didn’t test it out, but according to the gauge on the hpa tank, I am using very little gas for shooting. So the 26 cui tank filled up to 3000 psi should be enough for approx. 1000+ shots (I think its way more, but I don’t want to get too optimistic). I could refill this with my compressor or, for better comparability, out of my big 610 cui compressed air cylinder 25 times. That’s 25.000 shots. Refilling the big cylinder in a diving shop nearby normally costs me 5 bucks as a tip. So let’s say 500 cents for 25.000 shots. That would be 0,02 Cent a shot. If I fill it up with my compressor myself it should be even cheaper.

*No cooldown effect. Fire at will.

*Can be dismounted – converting back to co2 is done within minutes.

As a final verdict I guess: As I am already a pcp shooter and got all the stuff needed anyway, it was just a matter of 50 bucks and a bit of time. Still it only made sense, because I am having fun in doing stuff like this and I know, it gonna pay off quite soon. Next try is converting a bb blowback umarex p08, the cylinder should arrive within the next days. Maybe the blowback system changes things? Or the lighter bbs need less psi? We will see 😊

View attachment 423577
Excellent post.

I already have been using HPA with CO2 guns by using a dummy CO2 cartridge, a regulated air bottle and a paintball remote line (with slide check :)).
dummy_co2.jpg
I was thinking about buying the same CO2 to HPA adapter and have done research.
I considered the adapter because the dummy CO2 cartridge has the Foster nipple in the middle and it slightly interferes with holding the gun.
One advantage of the dummy CO2 is that is not attached to the pistol and can be moved to whichever pistol you want to shoot.
 
  • Haha
Reactions: Jarnold
and a paintball remote line (with slide check :)).
You'r way smarter than I am :D

I didnt know that type of co2-cartride-dummy, but it also looks quite interesting. So the foster nipple is basically between your fingers when holding the gun?

May I ask on how much PSI you are operating your co2 guns? And what's the result in fps?

Best regards :)
 
a bit of a hand scratcher but okay i am a tinkerer
so, you need to add a weaver rail and it is easy if you can do that
cut a slot dead center in a weaver base the width of the barrel stripe and epoxy it on than you can add a red dot or reflex sight
pick one that is cut out down the middle so the open sight still work

you can cut the slot with a table saw or i use a router and table with and mill bit
SAM_0200.JPG
SAM_0201.JPG
SAM_0202.JPG
 
  • Like
Reactions: Jarnold
Looks pretty decent to me, well done! There actually is a rail from Gamo itself - it will also fit the Crosman SR357 (same frame obviously).

But atm I have great fun shooting it with open sights (already got a rail and a reddot on my Walther CP88 competition 6"). I am thinking about designing and printing out a little LPA/glassfiber-holder with my 3d-printer to give it a "glowing" frontsight, also to cope with the shots going way too high. If I aim for the center on 9 yards, the shots nearly fly over the top of the target. 3 inches too high :rolleyes: But besides that, I like the gun a lot.
 
You'r way smarter than I am :D

I didnt know that type of co2-cartride-dummy, but it also looks quite interesting. So the foster nipple is basically between your fingers when holding the gun?

May I ask on how much PSI you are operating your co2 guns? And what's the result in fps?

Best regards :)
The Foster nipple is attached to the threaded hole in the middle and stays between your fingers when holding the gun.
I went up to about 1200 PSI and had no issues.
I do not remember the FPS, but I do not think it was much higher than CO2.
 
  • Like
Reactions: Jarnold
The Foster nipple is attached to the threaded hole in the middle and stays between your fingers when holding the gun.
I went up to about 1200 PSI and had no issues.
I do not remember the FPS, but I do not think it was much higher than CO2.

Having run or converted several Co2 guns to PCP, you're likely getting more power increase than you think. 1200 PSI is what Co2 produces in hot temperatures, but 1200 PSI air produces more velocity than 1200 PSI Co2. The reason you feel you haven't gotten much velocity increase is because Co2 report is louder than air. At 1200 PSI air you're probably getting 10-25% more velocity than on Co2 at 90 degrees F; yet not as loud report.
 
Having run or converted several Co2 guns to PCP, you're likely getting more power increase than you think. 1200 PSI is what Co2 produces in hot temperatures, but 1200 PSI air produces more velocity than 1200 PSI Co2. The reason you feel you haven't gotten much velocity increase is because Co2 report is louder than air. At 1200 PSI air you're probably getting 10-25% more velocity than on Co2 at 90 degrees F; yet not as loud report.
Even at the same pressure, air should give you a velocity increase compared to CO2.

I am sure I measured the velocity at some point, but don/t remember it now.
 
I have a Chaser in .177 that I converted to HPA and with a 1200psi reg I get 850fps for over 150shots 360cc tank
the best it ever did with co2 was about 650 fps on a Hot day
Still looking for a system to convert a Vigilante to remote HPA
Look at the adapter in the first post, choose the ST-W thread not the other thread.
It should work with the Vigilante.
I remember seeing that somewhere.

How did you convert the Chaser to HPA?
I have one, and might do it instead of buying even more CO2 cartridges.
 
How did you convert the Chaser to HPA?
I have one, and might do it instead of buying even more CO2 cartridges.

There is an adapter you can find on etsy (https://www.etsy.com/listing/1081599223) - and you can see some people using it in their youtube-videos.

I was also thinking about that, but when I got into pcp-shooting I simply sold my Chaser and bought the Diana Bandit. Same gun but on pcp - and the long barrel from the chaser fits as well :)

@elwoodblues
have a Chaser in .177 that I converted to HPA and with a 1200psi reg I get 850fps for over 150shots 360cc tank

Gosh, that's a lot of speed (y)
 
Look at the adapter in the first post, choose the ST-W thread not the other thread.
It should work with the Vigilante.
I remember seeing that somewhere.

How did you convert the Chaser to HPA?
I have one, and might do it instead of buying even more CO2 cartridges.
I have been working on my Chaser .22 HPA conversion for about a month. I wrapped it up last week and it works better than expected! I'm so curious about the improved power that I bought an FX chronograph yesterday (which is more than the cost of the HPA conversion) to do some testing on it but it's been too cold to put it to use. So far, at 23 yards I think I have about a 2 inch group going on my metal target. It may be better than that when the wind stops blowing and I can test it on paper. Honestly, it's way better than I thought it would be. I bought some JSB Exact Jumbo Monsters 25.39 gr and they hit with some force! I'll keep you posted an put together a parts list with some links and you can decide if it's worth doing to yours. It's a chaser rifle, not the pistol.
 
  • Like
Reactions: Jarnold
Go to Froggy's site on ETSY for the drop block, Aliexpress for the bottle and reg and Carm for good magazines

View attachment 425521
Nice work on those. Tell me a bit about the barrel on the one on the left. I'd like to change my silencer on mine away from the factory installed one that's on the barrel but I don't know how to get it off.

Also, where did you find the cheek riser?

Froggy's is the place for the drop blocks. You can find him on etsy and ebay too.


Froggy's also sells a heavier hammer spring. I tried it an found it pretty stiff but I have also done another spring tensioning mod to mine so maybe it was overkill. I IM'd him through the froggysairguns.com chat and he got right back to me with some tank and valve suggestions.

I got my bottle .45l bottle and 1800 PSI valve from amazon. If I buy another bottle I will get a slightly smaller one. It works great on the bipod and gets 100+ shots, its just a bit heavy up front off hand.

The gun specs say it shoots 500fps out of the box with Co2. I don't know if I ever achieved that speed. If I did, it was with Barracuda Greens.

I just took some shots with the chrono and here's what I came up with... one magazine with each of these 2 pellets:

JSB 18.13 - 670fps - 18.1 ft lbs -
JSB 15.89 - 704fps - 17.5 ft lbs -

Not mind blowing but still decent pesting power for the investment.

It's still too cold to set up targets to show the accuracy but it's fine for my needs so far.