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Lowering FPS in c02 NBB pistol
Posted: Sun Mar 11, 2012 11:22 am
by brandon
There's a CQB game coming up. The pistol I would like to use is a TSD M9 NBB, but the fps is a little hot.
I did come across this in my research:
I am not at all familiar with this gun,but most CO2 powered weapons are powered thru a valve that is struck by a hammer that is spring powered to meter a burst of propellant. If your are good at weapons repair/maintenance you may be able to adjust the spring tension on the hammer to a lower setting to reduce the amount of propellant dispensed at each firing. This will also increase your number of shots per cylinder. You would need to weaken the spring so that the hammer does not strike the release valve as hard as intended. Just a suggestion. I have done this in reverse to increase the power dispensed on CO2 BB/Pellet rifles and pistols.
Has anyone had any experience with this or have a similar idea?
Re: Lowering FPS in c02 NBB pistol
Posted: Mon Mar 12, 2012 12:14 pm
by Avenger
I would really like to know about this too...
Running it half out of gas works pretty well.
Re: Lowering FPS in c02 NBB pistol
Posted: Mon Mar 12, 2012 4:49 pm
by brandon
this gun stays pretty consistent until the gas is very low, but, i did manage to take it apart, cut a couple coils out of the spring and drop the FPS from 400 with .25 to around 250. I hope i didn't lower it too much.. but it'll work i suppose
feel free to assure me
Re: Lowering FPS in c02 NBB pistol
Posted: Mon Mar 12, 2012 5:07 pm
by Avenger
Awsome results:)
Re: Lowering FPS in c02 NBB pistol
Posted: Tue Mar 13, 2012 2:15 pm
by SteevoLS
250 with .25s is just about perfect for a sidearm (in my opinion/experience). Good job.
Re: Lowering FPS in c02 NBB pistol
Posted: Wed Apr 11, 2012 3:58 pm
by Gerbilizer
Was the spring located underneath the hammer?
Re: Lowering FPS in c02 NBB pistol
Posted: Sat Apr 21, 2012 12:14 pm
by fallout11
You can also cover the hammer contact area (where it strikes the valve) with something more shock absorbent (i.e. softer), such as thin sorbo, or install a small spacer around it (like a shim, with a hole in the middle) so that when it strikes the valve pin it no longer presses it in quite as far on full stroke. These are both old techniques from the old days of paintball, when all the guns were CO2 powered and open-bolt blowback designs (and many didn't yet have velocity adjusters).
Re: Lowering FPS in c02 NBB pistol
Posted: Sat Apr 21, 2012 12:18 pm
by Avenger
Do you guys know if these techniques would apply to a revolver? I really like Fallout's method because it isn't permanent.
Re: Lowering FPS in c02 NBB pistol
Posted: Sat Apr 21, 2012 12:35 pm
by fallout11
I modded my CO2 revolver with the 2nd method I mentioned above, using a thin washer (a gearbox shim with the inside hole slightly enlarged) to surround the protruding valve pin. When the happer strikes it to activate the gas release, it simply cannot move in as far, reducing the amount of gas released. I secured it with some adhesive which so far has stayed in place (knock on wood). As always, YMMV.