Some more P17 fun!

[Airnut]

Well, it was cold yesterday and I didn't have anything on my plate, so I decided to finish my P17 build.
I had machined out an adjustable piston awhile back but never installed it. I figured it would be a good time to do a .22 conversion and install the
two Oring adjustable piston. Well, that didn't work out to well more on that latter! I wanted to make a longer barrel but didn't want to drill out the stock to accommodate the full-size barrel as I have seen done many times. I came up with the idea to turn down the barrel on the muzzle end so it would fit the stock barrel pocket and extend out the end about a half inch or so. The small barrel looked very funny sticking out the end so I made what I will call an aliment bushing to cover the end and also keep the barrel aligned and secure in the gun. My goal was the get the most barrel length without changing the guns overall profile too much. With all that being said I grabbed my barrel blank and off I went to the lathe. When complete the new barrel was 8.25" long. I gained about 1.5 inches over the stock barrel. I installed the piston and barrel, and everything fit great.
I set the piston length 1/64" longer than stock to start with. I grabbed my .22 pellets and headed to my range to test fire the gun and as some of you may have already guessed! I grabbed the wrong #$%^& barrel blank at the outset. What a bone headed thing to do. And to make matters worse. I never noticed it when I crowned the barred and ground the lead. A Total brain fart.
But all is not lost I did learn a few things. One being that I don't think that this process would work on a .22 barrel. the turned down part that goes into the stock barrel pocket would be to thin and fragile. So drilling out the stock would be the only way.
I shot it over the chrony a few times and was surprised at the velocity H&N Terminators 7.2 grains @ 465 10 shot average with 3 fps SD.
The base line for this gun was 425.  The only mod was dual piston rings. Endless I hit it prefect the first time there may be room to get a little more out of it.

[Airnut]

more pics

[avator]

Frank, nice job.
I will offer a tip.
Do the champagne glass mod to the breech end of the barrel. It makes loading pellets much easier for sausage fingers blokes like me.

[Airnut]

Thanks Bill!
I have never seen that mod before.
The profile reminds me of an old style push rod end. I will have to give it a go on the next (.22) barrel.

[avator]

I sent a couple of these pistols off to Stalwart for his magic treatments including teflon trigger coating, power mods and other things a few years ago. This was one of the things he did to them. They returned to us amazing. Hard to believe from a $7 liquidation sale gun.

[Airnut]

Yep, some of my cheepest guns only needed a little TLC to perform well.
Kinda makes me wonder why the manufacturer didn't do it in the first place.(dam bean counters)
On second thought if the manufacturer did it then we wouldn't have anything to do.

[avator]

I had some paintball marker parts and tanks Erik wanted for some projects he was planning that I had picked up at a second hand joint. He offered to mod the 2 pistols in trade.

[Airnut]

 I finally finished my .22 barrel today and it turned out to be a 1/2" over stock length.
 I don't know if it's just me, but this thing feels to have a tiny bit of recoil.
 I don't know what would be normal for this gun as far as velocity goes. Here are the numbers.
 Maybe some one knows and can chime in. I have seen that some people have reported 350 FPS but I don't know with what pellet weight.
 The gun shot pretty accurate at 18 yards the two far left shots were all me. Take out them two and its not a bad group for me.

 RWS Hobbys 11.9 grains
1. 392
2. 397
3. 400        Average 398 fps  fpe 4.1
4. 401
5. 400

 H&N Terminator's 16.36 grains
1. 352
2. 353
3. 352         Average 354 fps  fpe 4.5
4. 356
5. 357

[Airnut]

oops!
forgot pic

[jackssmirkingrevenge]

I don't know what would be normal for this gun as far as velocity goes.

Those are some good results!  With my 0.22 conversion I got a maximum of 330 fps with 14.3 grain Crosman pellets in a standard length barrel.

[WobblyHand]

I don't know what would be normal for this gun as far as velocity goes.

Those are some good results!  With my 0.22 conversion I got a maximum of 330 fps with 14.3 grain Crosman pellets in a standard length barrel.

I managed to get 362fps with 14.3gr CPHP's and 345fps with 15.9gr JSB's on my 0.22 conversion.  I did the JB Weld epoxy shim and machined the minimum to just get cam over.  Also added a narrow slot in the epoxy across the full face to allow the air to escape.  I did not modify the valve or transfer port.

[Airnut]

The only thing I did was machine a custom adjustable piston with two polyurethane orings. I set the piston length 1/64" longer than stock. That left me with a little over 1/128" head space.
The only thing I did to the transfer port was to clean it up a little. Stock port was very rough. Looked like it was as casted with no maching of any kind.