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All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Share Your Simple Home Projects (TRICKS-N-TIPS) => Topic started by: a1rgunz on September 01, 2017, 09:14:41 PM
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I've loved the Beeman P17 going back as far as when they were called the Marksman 2004. I decided to go a little more extreme than the usual trigger tune on my most recent purchase. It all started with finding an old Crosman .22 barrel in my shed. I chucked the barrel in my 1/2" drill and turned down part of the barrel with my 1x30 sander to fit the action. I also drilled out the barrel hole on the "slide" to accept the wider diameter barrel. I replaced all the seals, trimmed down and smoothed the end of the valve stem to improve air flow, and applied a sparing amount of Super Lube.
It looked pretty good when all put back together:
(http://www.airgununiverse.net/wp/wp-content/uploads/2017/09/08171716151.jpg)
It would shoot Hobbies at 375 fps and SuperDomes and CPHPs at 340 fps. At 10 yards, the groups were .5". Taking it back to 15 yards, that opened to 1.5". Not good at all. RWS pellets shot a little better than the CPHPs, but not great. I pushed a CPHP through and realized the barrel was oversized when no rifling marks were present. Superdomes would push through with only light marks to their skirt.
I rummaged through my old Crosman parts bin and found a nice .177 barrel. I trimmed it down to 14.5", recrowned, added a nice lead in for easier loading, and pushed a pellet through. Nice marks on both the head and skirt - should be a winner.
I made a shoulder stock from an old piece of steel I found. Cleaned it off really good and sprayed with bedliner. I took a cedar stick, shaped it to form a buttpad. I still need to take another piece of that stick and form a comb, but I've got a bad case of tennis elbow right now, so that's going to have to wait. Here's how she looks now topped with a CVLife compact 4x32:
(http://www.airgununiverse.net/wp/wp-content/uploads/2017/09/0901171120b.jpg)
(http://www.airgununiverse.net/wp/wp-content/uploads/2017/09/0901171120a.jpg)
I removed the lock ring from the objective and adjusted it to be in sharper focus at the closer ranges I plan to shoot this at. This is a good trick to use on a cheap scope like this. So far, the scope is holding zero great.
The stock .177 pistol would shoot H&N Sniper lights at 400 fps. It now shoots them at 483 fps, giving me a gain of 1.2 foot pounds of energy. At 15 yards, my group size has shrunk to .34", so I'm happy with the accuracy. It's really quiet too. There's still a few things I need to do, like make the comb, paint the barrel, and clean up a few rough edges here and there. I also want to open the port up and see if I can squeeze a couple more fps out of it.
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Very cool! Looks awesome!
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Nice work. Good luck with it.
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Very cool!
Been wanting to do something like this for years, I've had a bunch of these over the years, still have two, but never have gotten around to attempting it, thanks for sharing!
:-) chickie
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Nice project. I like the shoulder stock scheme. I'm working on converting a Crosman Vigilante into a carbine.
Your accuracy claim @ 15 yards is impressive. Have you done any work on the muzzle? Are you using a rest or shooting offhand?
Keep up the good work.
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Thanks everyone, its been fun!
Have you done any work on the muzzle? Are you using a rest or shooting offhand?
I sure have, the muzzle is recrowned. I've been shooting off a rest. Offhand, I can manage to keep my 1.25" spinners moving pretty good.
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Now that my 3 day work week is over, I decided to shoot a fresh group to share. I'm using H&N Sniper Lights, shooting an average of 483 fps, target at 15 yards, from a rest. My target is a clean area of cardboard. The bullseye is a shot at the cardboard. I then proceed to aim at that shot for the group. Here's the bullseye and subsequent 5 shot group:
(http://www.airgununiverse.net/wp/wp-content/uploads/2017/09/0905170842.jpg)
Here's the CTC measurement:
(http://www.airgununiverse.net/wp/wp-content/uploads/2017/09/0905170843.jpg)
Here's the outer measurement:
(http://www.airgununiverse.net/wp/wp-content/uploads/2017/09/0905170843a.jpg)
Subtracting .177 from .416, you get .239. Of course, I'm shooting domed pellets into cardboard, so these aren't going to be Olympic quality measurements. ;D Regardless, I'm pretty happy with both the performance and accuracy. Here's some more chrony data:
Crosman Premier Heavies: 412 fps (Finally hit 4 FPE with something!)
Crosman Destroyer EX: 481 fps
RWS Superdomes: 451 fps
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Awesome.. I do think your stock numbers were very low.. A new 117 oring on the piston would likely give you another 20-30 fps ..
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Make me wonder if the longer barrel is whats causing the lower FPS numbers.....
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Make me wonder if the longer barrel is whats causing the lower FPS numbers.....
he chronied before the barel mod
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With the stock .177 barrel, it was shooting 400 fps with H&N Sniper Lights. When I switched to the .22 barrel, it could hit 375 fps with RWS Hobbies and 340 fps with some heavier pellets. Since that barrel was oversized, I decided to try a longer .177 barrel. It now shoots 83 fps faster than the original barrel. I hope that clears up the confusion!
Rob M, I have a 117 in there now. Went ahead and replaced all o rings while I had everything torn down. The pistol had quit holding air, turns out there was some oily crud in the valve. Now that it is cleaned up, with a light touch of lube and new seals, it holds air great.
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gotcha ! sounds good !