Crosman Crosman 3622 upgrades

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Gibsonvair

Gibsonvair

Member
Oct 18, 2022
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Frankton
I am very happy with my Crosman 3622. I have worked on the trigger, valve and barrel. I installed a .177" transfer port and bored the valve and barrel to the same size. It gets 20 shots around 18 ft/lbs with 16.01 JTS pellets. The trigger is nice and accuracy is good out to 30 yards, for sure. I pick it up to pest around the house and it is so easy to pump back up. I added a Buck-Rail fill cap, adaptor and modular moderator. Today I ordered a Magnum Air power trigger, just because this gun deserves a metal trigger now. I put brass shims around the barrel bands, and re-crowned the barrel while trying to get accuracy, but I think the JTS pellets might have been all it took. While I am pleased, I am wondering what effect opening up the end of the valve would have. (picture stolen screen shot from Al's Airguns YouTube channel.
Why is that hole so tiny?

Screenshot (410).png
 
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Gibsonvair said:
That is the encouragement I needed. The carb jet idea would keep me from screwing it up as I am not sure a replacement valve is available.
Click to expand...

Put the carb jet to the inside.

I am fairly certain Crosman would sell you any needed parts should something go afoul.

That tiny hole is a restrictor. The larger the hole the more the air reservoir will augment the plenum. That is my thought. For me, 16+ shots is enough. I am now getting nearly 30 and the advertised 24 is a piece of cake at 16 fpe average. I think thye JSB 18 would like a little more velocity for best accuracy and I would be okay with 16 shots and improved accuracy to 30 yards.

It is weird, sort of, that my two Urbans enjoy CPHP and my 3622 does not especially care for them but loves the JSBs.
 
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My goal is as much power as possible with around 20 consistent shots, so maybe just a little more power. The tiny (85cc?) tank will require a lot of efficiency. I love the weight of this gun with an aluminum breech. Mine weighs 5lbs 3.5oz scoped. I have seen where 20ft/lbs was reached, but now I can't find where I saw it. I can get 20 ft/lbs as is, but it is a down hill all the way on the shot string, no nice curve.

IMG_2635.JPG
 
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3Crows said:
Put the carb jet to the inside.

I am fairly certain Crosman would sell you any needed parts should something go afoul.

That tiny hole is a restrictor. The larger the hole the more the air reservoir will augment the plenum. That is my thought. For me, 16+ shots is enough. I am now getting nearly 30 and the advertised 24 is a piece of cake at 16 fpe average. I think thye JSB 18 would like a little more velocity for best accuracy and I would be okay with 16 shots and improved accuracy to 30 yards.

It is weird, sort of, that my two Urbans enjoy CPHP and my 3622 does not especially care for them but loves the JSBs.
Click to expand...
I need to to get some JSB 18.1's to test anyway. I am going to look for my shot string the last time I tested it.
 
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I was able to break into the Bushnell scope and play with the objective lens adjustment. It now focuses well from 15 to 50 yards and is moved to the 3622. Magnum Air Power trigger group installed. I still want to add a third adjustment screw. The weight is now 4lbs. 15.7 oz. with scope, aluminum breech, adaptor and silencer, trigger group and scope.

3622-1.jpg


3622-2.jpg
 
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Opening up the the inlet hole into valve could potentially add a few fpe, but you'll probably develop a (or worsen) shot "ping"... Not a huge issue but bothers some. I've had/have pcp's that sound like a metal pole getting struck when fired.

One question, how is the valve secured in the tube? Doesn't seemed pinned into place on the sides from what I can see in photos...
 
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Just Zack 2 said:
Opening up the the inlet hole into valve could potentially add a few fpe, but you'll probably develop a (or worsen) shot "ping"... Not a huge issue but bothers some. I've had/have pcp's that sound like a metal pole getting struck when fired.

One question, how is the valve secured in the tube? Doesn't seemed pinned into place on the sides from what I can see in photos...
Click to expand...
There are indents or crimps at the back of the air tube that keep it from moving rearward. I think the forward trigger screw protrudes into a slot or ring turned into the front of the valve. I am not planning on going over 2,000 p.s.i. with this rifle. I just bought a Discovery for that. Maybe the ping is why Crosman did the small hole. Some have speculated it is to keep the shot sting consistent. I guess I can test both of those theories
 
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Was going to say to open up barrel and valve exhaust ports to 9/64", but seems you already went to 11/64" or so with a matched TP bushing ...

Playing with the hammer/striker spring tension will affect the bell curve of the shot string. If peaked at first with steady decline, reduce hammer spring tension. If starting with too low velocity then velocity peaks at lower pressure then increase hammer spring tension. Takes a bit of fiddling to get optimized for a flat-ish curve.

That tiny inlet hole will starve the valve to some extent, limiting peak power. I don't own a 3622 so not sure how far you can bore it out. Smaller transfer port bushings (between valve and barrel) can level out the bell curve of shot strings also, at the expense of peak power.

If someone wants "all the beans"... big ports, stout hammer spring and soft (or no) valve spring... Lol. Don't expect many shot though.

Apologies if my ramblings are redundant or otherwise well known. I'll be following silently from this point forward 😁
 
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Just Zack 2 said:
Was going to say to open up barrel and valve exhaust ports to 9/64", but seems you already went to 11/64" or so with a matched TP bushing ...

Playing with the hammer/striker spring tension will affect the bell curve of the shot string. If peaked at first with steady decline, reduce hammer spring tension. If starting with too low velocity then velocity peaks at lower pressure then increase hammer spring tension. Takes a bit of fiddling to get optimized for a flat-ish curve.

That tiny inlet hole will starve the valve to some extent, limiting peak power. I don't own a 3622 so not sure how far you can bore it out. Smaller transfer port bushings (between valve and barrel) can level out the bell curve of shot strings also, at the expense of peak power.

If someone wants "all the beans"... big ports, stout hammer spring and soft (or no) valve spring... Lol. Don't expect many shot though.

Apologies if my ramblings are redundant or otherwise well known. I'll be following silently from this point forward 😁
Click to expand...
The rifle is tuned very well, giving me 20 shots between 17.5 and 18 ft/lbs. The next 10 shots, though slower and slower, were still decent. I am new (two years in) to airgunning, but it is a fun hobby for me and less expensive than cars. My goal is 20 shots with as much power as I can wring out with less than 4% deviation. This is my third pcp to try my hand at tuning. I bought a Benjamin Discovery to play with next.
 
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