.22 Cricket mini Carbine Power Tune

[CampFussell]

Good to see you on here Charlie! Bout time ;-) LOL

Any plans for installing a longer barrel on the mini carbine and tuning for the 25 gr RD Monsters?

Fuss

 

[CampFussell]

Thanks Charlie

I'm guessing the problem with the longer barrel on the mini will be the shroud? I really like the full length shrouded barrel on the mini!

Look forward to it man!

Fuss

 

[ackuric]

Charlie, if 20% weight increase causes damage then I would be suspect of the integrity of whatever is vulnerable to terminal damage...thats just in my opinion...nothing in our airguns should be that close to failure...we should have bigger safety margins...these are weapons intended to hunt.



You won't see a mini cricket carbine with a 15~" barrel hitting 880 FPS with 25 gr with near factory reg pressure and OEM striker weight / spring weight. Just isn't happening IMO. You could alternatively run higher reg pressure, and make the valve easier to open via balancing, or reducing poppet OD and running a material with higher young modulus such as PEEK. That will remove the requirement to add spring or striker weight...JMO



What is the sealing margin for the mini cricket valve seat and poppet? I personally run between .015" - .025" depending on the intended output pressure.



-Matt 

 

[Dairyboy]

FWIW my WARP with a 16" barrel maxed out got 880fps with the 25.39gr but was with a 2800psi reg set point. I ordered a 20" barrel for it instead.

Totally different gun I know but doesn't change the fact that it's hard to get there. 950fps with the 18gr is easy at 2200 psi but getting it up there with the 25.39gr isn't. Now I didn't add a heavier hammer either but did crank on the hammer spring.

 

[zx10wall]

FWIW my WARP with a 16" barrel maxed out got 880fps with the 25.39gr but was with a 2800psi reg set point. I ordered a 20" barrel for it instead.

Totally different gun I know but doesn't change the fact that it's hard to get there. 950fps with the 18gr is easy at 2200 psi but getting it up there with the 25.39gr isn't. Now I didn't add a heavier hammer either but did crank on the hammer spring.

Dang, that is 190 bar ~ 2800 psi. 

With Fuss's .22 Cricket (17.5" barrel me thinks) and .25 HS (also added plenum and port/polish with weaker valve-return spring), I saw a max of 910 fps with 25gr. That was at 168 bar which I wasn't about to stay at. Ended up setting is at 150 bar and got 885 fps for 32 or so shots from a 235 bar fill. 

 

[zx10wall]

C'cut, you need to do the work on this Mini for research purposes alone , it's a must now. If you end up modding the Taipan, you can port/polish the firing-valve and install a .25 HS. Holler at me as I have many of them. No need to enlarge the other ports. I would also "swiss cheese" the reg spacer to create a little bit more plenum space and up the reg to about 150 bar. 

 

[Dairyboy]

FWIW my WARP with a 16" barrel maxed out got 880fps with the 25.39gr but was with a 2800psi reg set point. I ordered a 20" barrel for it instead.

Totally different gun I know but doesn't change the fact that it's hard to get there. 950fps with the 18gr is easy at 2200 psi but getting it up there with the 25.39gr isn't. Now I didn't add a heavier hammer either but did crank on the hammer spring.

Dang, that is 190 bar ~ 2800 psi. 

With Fuss's .22 Cricket (17.5" barrel me thinks) and .25 HS (also added plenum and port/polish with weaker valve-return spring), I saw a max of 910 fps with 25gr. That was at 168 bar which I wasn't about to stay at. Ended up setting is at 150 bar and got 885 fps for 32 or so shots from a 235 bar fill.

Yeah I think it's more the plenum size than anything combined with the short barrel. Also the barrel on the WARP is a MMHF barrel same as the marauder barrel. Super accurate but very tight so you lose a good 20-30fps over other barrels. And then on top of that most of the RD monsters I've headsized are in the 5.55 range so that slows it alittle also.

To put in perspective same gun same barrel length same reg pressure in .30 could max at 880fps with the 44.75gr pellets. So I think the tighter bore holds it back.

 

[Dairyboy]

Just realized my logic didn't make sense if plenum was too small couldn't make big power with the .30....so must be the barrel is tight

 

[zx10wall]

Think of it in terms of a hydraulic cylinder. The larger the bore of the cylinder the more force that is produced from the same pressure as compared to a smaller bore. Similar but not the same as the compressed air is expanding and this is why barrel length is crucial.

It takes a lot to get that little .22 25gr moving with good speed. The same force can move the .25 25gr JSB faster and easier. 

 

[ackuric]

+1 zx10, Also, the barrel length on an air gun is basically a stroke length and the pellet is a piston...the longer the stroke length the more energy transfered during the stroke. Stroke duration also increases energy transfered hence why heavier pellets that move slower and spend more time engaged with rifling typically see increased energy outputs. 



I know for a fact with ports stretched far enough, and regulated pressure increased enough, a 15.5"~ barrel can hit 880~ fps with 25 gr. What barrel length lacks, pressure and port size can always make up for...its just a matter of the two being within reason and within the rifles limitations be it space or material strength. 



Dairyboy, what was your port size when you hit 880 @ 2800 psi? Kind of curious...if I had to guess I'd say...between .15" and .16"? 



Taking that same rifle parameters but porting up to .196" allows you to hit 880 @ 2200~ psi opposed to 2800~...but that is very extreme porting, nearly 90% of bore.



-Matt

 

[Dairyboy]

Matt,

My port I believe is .187 on it. The TP and valve are .250. However when doin testing on the .22 at that high pressure reg setting was right after I swapped off the .30 barrel. I never tested if I could hit it at lower pressures or not. I might do the testing again at different pressures to see while waiting on the longer barrel.

Also I'm not 100% sure my reg pressure gauge is dead on. It could read a little higher than it actually is?? 

 

[ackuric]

Yea if its a mini gauge they are grade D and at best within 5%, they are commonly around ~100 psi off if not more. I always calibrate mine by taking the lens off, filling to 2k dead on with my liquid gauge and then bending the mini gauge till it reads 2k. Still doesn't improve their accuracy over their full range but its for the range I regulate around. I have found them being upwards of 200~ psi off. Where as my liquid filled grade A gauge is within 1% accuracy...



What was the plenum size? If its close to 20 cc then you likely have near a 20% pressure drop. If your gauge is 100 psi high that would put the average pressure from 2700 down to 2430~, which would then put you at around 900~ FPS max. Was the barrel 16" on the money or closer to 15.5"? 



Your bolt probe could be interfering with your port size unless its really thinned down to accommodate the .187 porting. You would need a retracting bolt probe OR one thinned down to .115"~ and NO greater...



-Matt

 

[zx10wall]

I just got done with a .22 Cricket Carbine (not pup) tune. Port/polished all TP and radiused firing valve with oval barrel TP. My word, opening the ports makes a world of difference. No added plenum. .25 Cricket HS and no added weight to hammer. Installed a slightly weaker firing-valve return spring. “Swiss cheesed” the reg spacer and again, no added plenum tube. Reg set to 140 bar. Plateaus at 920 fps with the 25.39gr RD Monsters. I backed it down to 900 fps with HST. 

I will test shot count and accuracy later. It has a wonderfully smooth shot cycle and is very tight over the chrony

 

[ackuric]

Opening up ports works wonders. Blow through a coffee stir straw, then a normal straw, and then a 1/2" pipe, and tell me how that relates to trying to send a projectile as fast as you can through 15-24" of barrel in under 3 ms..



Installing the weaker valve spring is definitely another way to skin the cat opposed to adding more spring or hammer weight. I run the lightest spring I can, that is roughly 3 lb / in....in my valves. I also keep my poppet sealing margin minimal to reduce poppet od which aids greatly in required force to open valve, because after-all the pressure against the poppet is the main force you fight to open the valve...



I really wonder what the poppet OD and seat OD of the crickets are...and their poppet material.



-Matt

 

[CampFussell]

Wow, lookin' good Derrick. Makes me wish I would have kept my .22 Carbine now ;-)

 

[zx10wall]

Accuracy is good. I got 25 shots from a 240 bar fill with the 25gr RD Monsters ~ 45.6 FPE. Groups are both 14 shots a piece from 40 yards. Shot the first one on bottom and dialed a click of elevation and a click of windage, topped off and shot the top one. The dime took one for a giggle. It took a bit of time to fish it out of the trap box. 

 

[ackuric]

I have some interesting dime / quarter / nickel shots haha. I love when the lead hits so hard it fuses with the metal. Splat.

 

[CampFussell]

Man, I'm digging that black stock.

Derrick, you've taken the "Dime Challenge" to whole new level!!!! LOL

Thanks for the info!

Fuss

 

[Centercut]

@zx10wall, Derek. What if anything did you do to the action block port from the valve port to the barrel port? Nice job and very good power. 

Will let you know which one Nick decides on. He has both while I’m in Hawaii this week on business. I’ll definitely PM you if he decides on the Mutant. Even if he does I’m still going to port and polish the Cricket mini, add the Plenum and Huma and see where that gets me. Is the reg on the Mutant hard to adjust? Seems without a reg tester it would be a pain...Same for the Cricket really...

 

[zx10wall]

Hawaii on business, say what  

I first replaced all o’rings and rebuilt the reg setting it at 140 bar. I ported/radiused/polished the firing-valve. I installed a weaker valve-return spring. I Swiss cheesed  the reg spacer. Reassembled and tested. My plateau max was 870 fps. Needed more.

BTW, this is some of my trickery and I don’t think there is any reason to hide it. Guys, you can ruin your high-dollar beloved PCP if you get hamfisted. You’ve been warned!

Rather than up reg pressure more, I decided to open the other TPs. Working through the straight threaded hole that one of the two set screws normally resided to secure the firing-valve to the action, I carefully used a long shank carbide burr to open up the action port several thousandths. I used this same burr to open and oval the barrel port carefully radiusing the path toward the muzzle. I polished with a rubber abbrasive burr and 3M polishing cloth.

Opening these two ports alone upped my plateau max to 920 fps gaining 50 fps. That was impressive to me.