GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Engineering- Research & Development => Topic started by: ag 101 on May 15, 2014, 05:40:11 PM
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Hi everybody,
I have been playing for a while with my 16 ga, Philippine made, shotgun.
Have made a few mods to improve the performance. I had a new brass hammer made for it, but can not get a punch as much as one would expect from a CO2 gun.
My question is, Since the hammer sits tightly inside the tube, would it be better if I added an o-ring at each ends of it?
Could that improve the movement and maybe increase the speed it travels, to hit the valve? How about the spring?
Your responses are much appreciated.
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No clue on the mechanical design your working with ? ... How hammer is held at full cock etc ... ?
If you reduce the bearing area of the hammer tube contact, it will reduce contact friction.
This could be simply leaving full diameter of hammer at each end, but reduce the diameter between ends by .005-.010" ???
You could take entire diameter down a tad and add nylon/delrin/teflon contact buttons perhaps ?
All i got for what i know of these guns which is nothing :P
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It is a primitive kind of design. I guess these guns were built with whatever was available.
I'll try to take a few pictures of the parts and forward them to you, this weekend.
If the friction is reduced and hammer travels faster, maybe it could generate more gas expansion and maybe more power?
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Do a few searches ... Bob "resterne" has shared tables on Co2 expansion / pressure that may shed some more light.
Honestly with Co2 at @ 70*f only producing in around 1000# your not going to find massive amounts of power no matter how much you get valve to pass.
This JMO ....
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Thanks Scott, I'll do that.
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If you increase hammer strike past a given amount, all you will do is waste CO2 without increasing the velocity....
Bob
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Bob,
Thanks for your advice. In your opinion, which areas should be explored in order to increase the velocity?
I had the barrel checked and found out that it was not correctly shaped ( uneven).
I was lucky to find a 16 ga shotgun barrel with full chock and fit it to the gun. Now, I don't have any gas being wasted in the barrel.
I get %85 of the shots on target at 20 yards but would like to have more speed in order to reach 30 yards with enough power.
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I've never worked on CO2 larger than a .35 cal rifle, so really can't offer advice.... CO2 is limited in velocity compared to air, it works about like HPA at 700 psi.... To get more velocity you will need large ports, and that means lots of CO2 used....
Bob