Building My First PCP

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jdock5.0

jdock5.0

Member
Feb 7, 2022
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Pennsylvania, United States
Hello all new to the forum,

I used to be into airguns years ago but had to get out of it due to life changes. But now I can get back into it! 
So, looking to build my first pcp. 
Haven’t been up to date with all the new advances in tuning etc, last I remember a 40@40 tune with a .25 mrod was ballin!



option 1: 

disco tube, magnum air valve, 3k psi screws, stock single shot breech, Maximus barrel/donnyfl slingin slugs around 930-950. probably dressed in Boyd’s furniture 


option 2 

Mrod .22 same as above slugs at 930-950 20.2 or 23gr NSA or fx hybrid whichever 

(how do I even get that kinda power out of a .22 mrod?)



Looking to keep it Benjamin as that’s what I had as a young buck & growing up. I know shot count for the disco would probably be around 10 but that’s fine. Just haven’t seen anybody using the magnum air valve in my recent research. JSAR has a pretty nice looking valve option for the mrod but then again what do I know. 

Forgive me if this topic has been covered elsewhere, can’t figure out the search function on here yet.
Thanks everyone any info is greatly appreciated. 

 
A bottle fed Disco type build maybe?

1107201626b_HDR 3.1644279592.jpg

 
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Upvote 0
These links might be helpful to you then.

https://www.airgunsofarizona.com/index.php?p=catalog&mode=search&search_str=crosman+sear

https://www.airgunbuy.com

https://alliancehobby.com/shortytwo.htm

http://www.alchemyairwerks.com/store/c1/Featured_Products.html

https://www.bakerairguns.com/shop/parts/modification-parts/

https://cothranmachine.com/

https://www.crosman.com/contact Call with part number for parts

https://gmaccustomparts.com

https://www.jgairguns.biz/crosman-c-78_89/

https://onlinestore.magnumairpower.com/

https://maverickcustomairguns.com/shop/

https://onlinestore.magnumairpower.com/

https://mellonair.myfreesites.net/barrel-bands

http://mountainaircustomairguns.com/

https://www.pcptunes.com/crosman-airgun-mods-and-spares/

https://schaefershooting.com

https://ssl.tko22.com/

https://urgthrash.wixsite.com/squirrelmaster

https://www.scstocksandgrips.com/co2-and-pumper-stocks

Picatinny mount for 22xx tube

https://buck-rail.com/product/crosman-2240-dr-murfee-mount/

https://www.ebay.fr/itm/Crosman-2240-lower-picatinny-rail-mount/313143188751

https://www.amazon.com/Beamshot-Creates-standard-picatinny-barrell/dp/B00AT57CRU/ref=pd_sim_sbs_sg_1

Fill adapter w/gauge

https://onlinestore.magnumairpower.com/products/fill-adapter-with-gauge-burst-disc

Fill Check Valve

PCP check valve

https://www.amazon.com/Outdoor-Guy-Connection-Foster-Stainless/dp/B07D51SPZX/ref=pd_rhf_dp_s_pd_crcd_29/141-5469905-7923953



My 22xx mods

https://www.airgunnation.com/topic/crosman-rat-gun-gets-another-mod/?referrer=1

https://www.airgunnation.com/topic/i-built-an-arrowgun-recovered-from-the-crosman-green-forum/?referrer=1

https://www.airgunnation.com/topic/crosman-2240xl-2/?referrer=1

https://www.airgunnation.com/topic/the-true-cost-of-my-60-crosman-2240/?referrer=1


 
Upvote 0
It depends on what you want to do with the gun. Are you sold on the .22 cal? Or do you think maybe you might want to go bigger? This was my problem: I started with .177 then .22, then .257 and on and on. Now I am at .457 and loving it. Now, I wouldn't want to shoot pidgeons with a .457, but a .308? No problem. And that same caliber can down a coyote, no problem. The next question is: What kind of power do you want? Looking for the ultimate? Or maybe a step down from there? To me, the choice has been either Magnum airpower or Cothran valves. The Magnum valves will yield the "step down" performance, at the benefit of more shots per fill. Wheras the Cothran valves will yield the "ultimate" in power, at the expense of few shots per fill.

Cothran also offers stainless steel parts that are fully capable of higher pressures. And many do run them that way, myself included. The Magnum parts are made to be used on stock Discovery tubes. No one has been able to verify (to me) that these tubes are good past 3000psi...up to you. I run them at 3000psi on .257 and .308 cal airguns. And with good results, the .257 can make 50Lbft of energy and the .308 can make 77lbft of energy on factory made pellets. And each will yield 15 or so lethal shots per fill.

Now, my Cothran based airguns, one .357 and the other .457 can make 200lbft and 400lbft of energy with slugs that I cast. Each gets about 6 lethal shots per fill (3500psi). Each would be more than adequate to down a deer.

To continue a little, if you go M-rod, Cothran does make a valve for that too. It will get you around 150fps more velocity than the stock valve, figure around 1100fps on a .25 cal (yes I have one in my .25 Marauder). I can still get a dozen or so good shots per fill.

Chris 
 
Upvote 0
It depends on what you want to do with the gun. Are you sold on the .22 cal? Or do you think maybe you might want to go bigger? This was my problem: I started with .177 then .22, then .257 and on and on. Now I am at .457 and loving it. Now, I wouldn't want to shoot pidgeons with a .457, but a .308? No problem. And that same caliber can down a coyote, no problem. The next question is: What kind of power do you want? Looking for the ultimate? Or maybe a step down from there? To me, the choice has been either Magnum airpower or Cothran valves. The Magnum valves will yield the "step down" performance, at the benefit of more shots per fill. Wheras the Cothran valves will yield the "ultimate" in power, at the expense of few shots per fill.

Cothran also offers stainless steel parts that are fully capable of higher pressures. And many do run them that way, myself included. The Magnum parts are made to be used on stock Discovery tubes. No one has been able to verify (to me) that these tubes are good past 3000psi...up to you. I run them at 3000psi on .257 and .308 cal airguns. And with good results, the .257 can make 50Lbft of energy and the .308 can make 77lbft of energy on factory made pellets. And each will yield 15 or so lethal shots per fill.

Now, my Cothran based airguns, one .357 and the other .457 can make 200lbft and 400lbft of energy with slugs that I cast. Each gets about 6 lethal shots per fill (3500psi). Each would be more than adequate to down a deer.

To continue a little, if you go M-rod, Cothran does make a valve for that too. It will get you around 150fps more velocity than the stock valve, figure around 1100fps on a .25 cal (yes I have one in my .25 Marauder). I can still get a dozen or so good shots per fill.

Chris
Click to expand...

Yes I’m pretty set on .22, pigeons, starlings, but also the occasional ground hog at 60-100 yards. I believe a 45fpe .22 should do the trick at that distance with a hollow point slug, just speculating however. 
I really like the magnum valve idea, with the 26” barrel setup. Would you happen to have a shot string for the .257 gun? 12-15 shots with a decent ES is all I’d need as this is strictly a hunting setup. 


thanks chris 
 
Upvote 0
Sure:

From a 3Kpsi start pressure to an 1100psi ending pressure and with a 24.7grain pellet, I get:

963fps 50.9fpe

962fps 50.8fpe

959fps 50.5fpe

943fps 48.8fpe

931fps 47.6fpe 

921fps 46.5fpe

903fps 44.7fpe

887fps 43.2fpe

870fps 41.5fpe

857fps 40.3fpe

830fps 37.8fpe

811fps 36.1fpe

777fps 33.1fpe

This rifle is made of: Disco airtube, Magnum fill adaptor, Cothran rear cocker, LW barrel 24", Magnum valve (long intake so it covers the guage hole in the tube), P-Rod lower assembly, Baker big bore breech, Magnum hardened or whatever valve screws.

Hope this helps a bit.

Chris
 
Upvote 0
Sure:

From a 3Kpsi start pressure to an 1100psi ending pressure and with a 24.7grain pellet, I get:

963fps 50.9fpe

962fps 50.8fpe

959fps 50.5fpe

943fps 48.8fpe

931fps 47.6fpe 

921fps 46.5fpe

903fps 44.7fpe

887fps 43.2fpe

870fps 41.5fpe

857fps 40.3fpe

830fps 37.8fpe

811fps 36.1fpe

777fps 33.1fpe

This rifle is made of: Disco airtube, Magnum fill adaptor, Cothran rear cocker, LW barrel 24", Magnum valve (long intake so it covers the guage hole in the tube), P-Rod lower assembly, Baker big bore breech, Magnum hardened or whatever valve screws.

Hope this helps a bit.

Chris
Click to expand...

Thanks for that, wonder if I’m .22 it could have some sort of bell curve or a 20-30fps extreme spread for 10 shots, definitely turned down though yours is making massive power! 
 
Upvote 0
Iunno, but I bet that combo would blast a 22 pellet through the sound barrier!

You know, I bet if I turned my pwr adjuster out a little, I would get something of a bell curve. Although I'd bet it wasn't much of one. Seems the best way to do that is with a regulator...maybe, and there are regulators made for this kind of thing. I use my air rifles mostly for Jack rabbit hunting and the occasional coyote, so having 10 or so good shots is fine for me. Wouldn't be hard to do a bottle adaptation, just pick a bottle and make an offset adaptor to go between the end of your airtube and the bottle. And volume is key. My 45 has a 33 inch airtube on it, going to that from a 2260 length tube made a huge difference in both number of shots and velocity.

Chris
 
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