Hi Guys
http://i280.photobucket.com/albums/k...-Messenger.jpg
Despite what I said previously I have now sent off for a chrono (don't tell "She Who Must Be Evaded") and I can now do some sensible tests on the Smith & Wesson.
I think that pistol tuning is pretty much frowned on by "authority" since if you get it wrong (right?) you end up with an automatic firearms offence as you have a handgun. So now that I can check out what is happening I can try out a few modifications to up the power. I said I could think of three ways without too much trouble and so I'll try them. There is a fourth simple way but since that involves changing to the 8" barrel I already have I can't count that, mind you if somebody wants to send me the 4 & 6 inch barrels I am willing to check them out.
OK so in the interests of staying legal I will do the work a stage at a time and check after each one to see the results.
First up I will pack the hammer. Have a look at the first picture and the light coloured area shows the rear of the gun and the back of the hammer and front of the striker plate.
http://i280.photobucket.com/albums/k...rade/001-1.jpg
On this gun the hammer does not hit the gas release valve. It hits the striker plate and that in turn hits the gas release valve. This plate is also the safetey since it has to be moved up when the gun is cocked to move it out of the retaining notch and whilst it is in the down position it prevents the hammer from hitting the gas release valve.
I keep saying the gas release valve (GRV) as if it is some kind of mantra. It is! If this bit of kit fails on any co2 gun it becomes a club. What it does is allows a carefully measured dose of co2 to enter the magazine behind the pellet and we are on the way to that perfect score.
The length of time the valve is open dictates the ammount of co2 it releases. More co2 more power, less co2 less power. The length of dwell (time open) is a combined function of three things. The strength of the internal spring in the GRV, the strength of the trigger spring, and the clearance between the hammer and the GRV, or in this case the striker plate. Adjust any of these and you adjust the dwell, adjust the dwell and you adjust the power. So by packing the hammer I can override the GRV internal spring for a fraction longer because the hammer is now contacting the striker plate sooner and so staying in contact longer releasing more gas. The picture below shows the GRV on the left and the striker plate to the right of it in the light coloured square and when I have the chrono I will put a small piece of metal between the hammer and the striker plate then measure the speed.
http://i280.photobucket.com/albums/k...rade/003-1.jpg
Untill I do the check I have no idea how thick the piece will need to be and yes I will use more co2 per shot.
For mods to the valve the picture below may help.
http://i280.photobucket.com/albums/k...gramValve2.jpg
I'll come back when I have results.
Target Bunny
Mea imperare! Sputum facere tu felix laetitiam? Processus! Sputum fabricati diem.