2240 to HPA 30cal

[Prouzy]

I started this a while back at the same time as a .224 conversion, but time has been a challenge.  Given my time constraints, as well as certain limitations with equipment and ability, I wanted to do this predominantly drop in parts that I could modify as necessary.  There is nothing really new here, I have seen people do better, but thought this might be of interest for those who need to keep it simple.  The barrel is 9.75" in length, with OAL of the pistol at 13.5"  I have always wanted a big bore pistol, and often contemplate a DAQ (probably will some time) but just dont like the length.  I attempted to estimate my length tolerance and balance to shoot off hand, and came up with with I did.  Its actually not bad at all.

The first thing I did (after acquiring a 2240) was buy a 1/2" steel breech from Baker, as well as a .25 barrel to play around with.  I like it a lot and knew the .30 could be feasible.  I got a .300 TJ barrel sent to Roy at Mountain air, who machined the barrel as well as a new bolt.    I put it all together and was getting 280fps with 50gr JSB on CO2 @ 75degF.  I also tried some NSA swaged at 62gr, but did not have enough pressure to push them through 

I ordered an air tube from Baker (Disco), which is already drilled for for three retaining screws and fits trigger and breech assembly for the 2240 (for those who did not know).  I cut the tube to a shorter length to practice cutting to prepare for tapping.  I also purchased the foster fill assembly from Magnum Air Power.  I attempted to tap ( purchased the tap with guidance from the folks in another gate, Rob, IIRC) but was not going well by hand.  I live a bit rural, and had not met one of my next door neighbors in the 5 years living here, but my wife had, and reminded he is a machinist, score!  He is also into firearms, hunting, etc, so when I called him he was quite interested in what I was doing.  I brought a few example of PCPs, and he completely impressed and ready to jump in!  He tapped my air tube for me.

I bought a valve, retaining screws, and spring from Magnum Air Power and was impressed with quality.  I do not even know what the porting is, nor did I change anything and assume its not as large as I can capitalize on, including the original tune port (IIRC).  So I can only imagine Im choking here a bit, but that can mitigated by myself.  I cleaned up the tube end where it was tapped, or at least I though I did.  The valve I bought was the magnum valve with extender, which extends past where the pressure gauge WOULD be, as I did not want to put one in.  I may change that........ I know I had nicked the oring that seals the valve, because it was leaking first time I filled..............but those orings are so rigid.  I knew it, but thats okay.  Actually when I filled to 2400psi, leaking reduced to a much slower barely audible hissing which of course still indicates that is dramatic air loss.  However, Ive been waiting a long time to shoot this.

2400psi (leaking, so about 120 seconds between filling and shooting)
JSB 44.75gr .30
Shot 1: 585fps
Shot 2: 538fps
Shot 3: 485fps

At the moment I was just interested in what I could get to, 585fps.  Its the stock hammer, but that spring a bear to cock!  Im right handed, went with a left handed breech to improve reload time.  Im sure there will be further changes in porting, sping, hammer and fill pressure but thats where I am at.  I have not run any numbers, but hoping I can get to 700fps with 44.75gr would be nice.  The pistol serves to other purpose than going through the process and wanting something different and fun to shoot.  I can already tell this is going to be fun, its got a nice little recoil and hits pretty darn hard at pistol ranges 

Sorry, poor pic.  I plan on polishing everything, new grips, to dress her up a bit!

[rsterne]

Nice job.... Sounds like it might be a good candidate for tuning like a Big Bore.... two equal shots and a 3rd, slightly slower backup.... Alternately, a three shot bell curve at slightly less velocity....

Bob

[Prouzy]

Nice job.... Sounds like it might be a good candidate for tuning like a Big Bore.... two equal shots and a 3rd, slightly slower backup.... Alternately, a three shot bell curve at slightly less velocity....

Bob

Thanks Bob, thats what Im thinking too.  Im going to go for the two equal, if I can get it up there

[rsterne]

Judging from the shot string you had.... I would guess that with just a bit less hammer strike you could get 2 shots at about 560-570 fps, with the followup at over 500.... If you wanted a 3-shot string, it would probably peak at around what your 2nd shot is or a bit more....

Bob

[Prouzy]

I definitely have to work on the hammer strike.  The porting on the valve I just read is .150, and I am assuming the TP is much less.  So I may mess around with lighter hammer spring with current porting and see just how much I can get for a shot to shot consistency...................... after I fix the leak 

[Rob in NC]

Nicely done!
I just did similar not too long ago, but in 36cal.  I'm hitting around 50fpe with it for a few shots.  Havent messed with full tune yet as like you, limited on time and have other toys that have gotten my attention.

[Prouzy]

Nicely done!
I just did similar not too long ago, but in 36cal.  I'm hitting around 50fpe with it for a few shots.  Havent messed with full tune yet as like you, limited on time and have other toys that have gotten my attention.

I think we are on the same path, this is already well over a year and barely got to put it somewhat together. But I have my eye on a .35 in the near future  I love the feel of the .30, camt imagine the .36! Love those grips!

[Rob in NC]

This thing has been 8+ years in the making.
Got a .36 breech from a fellow named Bontranger who....waaaay... back in the day was making QB big bore conversions and then skipped town, leaving a lot of angry customers... but I got a (then groundbreaking) pistol from him and this breech. 

The grips are of unknown origin, but look to be RB...but I got them at the Hickory Airgun show this past year and they were unfinished. I've never known Ralph to sell unfinished grips.

The power adjuster is one I picked up off the Green forum years ago....

and the tube and internals were from Roy at Mt Air.     

could certainly relate when you lamented on how it felt going off with the recoil.... love it! haha

[Prouzy]

You certainly got me on the timeline! 

Roy has done several things for me, including the barrel on this one, from TJ.  He has done another barrel for me on the .224.  He does really nice work, and I like the fact he takes on what he can and knows he can do.  I will definitely add a power adjuster and a barrel or breech band............that little screw seems like it would overworked in the pressures/powers.  I wonder what I could get from a 2240 conversion to .35 rifle........

[CraigH]

Impressive builds!   

I do not have any big bores, but some of my 22XX and 13XX have little of their factory parts.   It is quite easy to have a 2240 with no 2240 parts!   

[Prouzy]

Thats true Craig!  And some may ask why?  But its in the process, and in the end, you have enough parts to make another 2240!

[Rob in NC]

Roys old site back in the day was largely responsible for my desire to mod Crosmans.  I've gotten quite a few items from him over the years. 

I did have that top end on a carbine wearing a Steve Corcoran stock but swapped uppers for a .25 DAQ upper recently.

Think you're correct in the 'why do it'.   This 9mm pistol was the first in some years I'd worked on, but still found it fun.  I've kind of gotten the bug again and have quite a few other parts so may just dress up a simple 2240.   I'd really wanted to go .30 as you did, but had the 9mm top end sooo....

Do like how compact yours is though compared to mine.  More like a true pistol.

[Prouzy]

Roy was probably the first person I spoke to when I got into PCPs, I blame him a bit too 
 
Those Corcoran stocks sure are nice, must have been difficult to part with, but my cabinet is like a revolving door LOL 

I specifically wanted to make this a pistol and not a carbine...........I hemmed and hawed about a DAQ pistol and shortening it, but that might have been sacrilegious.  At the time I decided on .300 was because NSA was developing slugs for typical airgun barrel sizes and I subsequently had a great deal of success with my Rainstorm II .30  At pistol distance, may not matter much, but they load real easy.  Once I get porting sorted out, will move on to testing those.