12 gram efficiency on a classic valve?

[Sn toter]

I'm building a new project and just curious as to what the norm is for a 12 gram shot count. It's a vert 12 gram changer with microline to the classic valve, level 7 bolt. Are there any ways to increase the shot count? thanks,
J

[warbeak2099]

I have heard that the efficiency is around 20 shots to a cartridge if not less. I have also heard it is better when not using the 12g in a vertical position.

[tymcneer]

There was talk on AO, a while back, about decreasing the dumpchamber volume and increasing the operating pressure. I believe that Tom Kaye even chimed in, and stated that he had done similar experiments, and there was an improvement in efficency.

Ty

[snoopay700]

There was talk on AO, a while back, about decreasing the dumpchamber volume and increasing the operating pressure. I believe that Tom Kaye even chimed in, and stated that he had done similar experiments, and there was an improvement in efficency.

Ty

Yeah, basically you decrease the volume till the operating pressure rises form 400 to about 450 and you'll get better efficiency.

[Sn toter]

There was talk on AO, a while back, about decreasing the dumpchamber volume and increasing the operating pressure. I believe that Tom Kaye even chimed in, and stated that he had done similar experiments, and there was an improvement in efficency.

Ty


interesting, how specifically would one go about that?

[snoopay700]

interesting, how specifically would one go about that?

Get or make a metal washer, unscrew the powertube from the rail, get it to fit, and put it in. Ideally you would weld it there, but if there's a big hole in the center where the air can go through then it should work fine.

[tymcneer]

If you are lucky enough to havea very early valve, you remove the power tube assembly first.

If you are not so lucky, you have to do the following kinda blind.

You need to take up some of the dump chamber's volume. There were a number of suggestions, but epoxy putty seems to be the best bet. I suppose you could use ball bearings or something like that, so long as they can be inserted into the dump chamber.

Ty

[Altec]

There was talk on AO, a while back, about decreasing the dumpchamber volume and increasing the operating pressure. I believe that Tom Kaye even chimed in, and stated that he had done similar experiments, and there was an improvement in efficency.

Ty

I remember one guy getting about 35 shots doing this. Seems to work. I have to wonder what the max output on the regulator is though.

[tymcneer]

The regulator can go as high as the input pressure, but will start leaking through the velocity adjuster at some point. Our usual solution is to remove the power piston, and tighten down the allen screw in it. This increases the maximum pressure it will allow, before venting.

Ty

[Sn toter]

Awesome, thanks guys. Guess I have some experimenting to do while the rest of the marker is away getting ano.

[mr doo doo]

i get around 19-20 shots with a 12 gram either vertical or horizontal. no mods no nothing, just with a typical classic valve ;)

[Altec]

The regulator can go as high as the input pressure, but will start leaking through the velocity adjuster at some point. Our usual solution is to remove the power piston, and tighten down the allen screw in it. This increases the maximum pressure it will allow, before venting.

Ty

Thats what a meant. At what PSI the relief valve kicks in. If its easy to bypass then no worries. :)

[babyface]

i get around 19-20 shots with a 12 gram either vertical or horizontal. no mods no nothing, just with a typical classic valve ;)

at what velocity did it chrono in at?

[Turbo Chicken]

i made a post a while ago on AO and rrfireblade replied with some tips ...

http://www.automags.org/forums/showthread.php?t=208650

there it is ... pretty much what's been said here

to get the right amount to use to devolume the chamber i always thought about using silly putty measure the volume ... then use something more permanent...

[mr doo doo]

at what velocity did it chrono in at?

280 +/- 7. not that bad.

[SocialD]

interesting, how specifically would one go about that?

I used to make some spacers for Fox River Games Hypermags. You need to remove the power tube assembly to get into the air chamber. I use to make aluminum spacers with an o-ring groove to keep it for rattling around in the chamber. Reattach the power tube. You are likely also going to need a stronger spring pack. One of two things will happen if you don't have a strong enough spring pack: either you won't be able to get your velocity high enough or you won't be able to get it low enough. I don't remember which it is.

I think that I might still have a spacer or two of them lying around for classic mags.

[snoopay700]

I used to make some spacers for Fox River Games Hypermags. You need to remove the power tube assembly to get into the air chamber. I use to make aluminum spacers with an o-ring groove to keep it for rattling around in the chamber. Reattach the power tube. You are likely also going to need a stronger spring pack. One of two things will happen if you don't have a strong enough spring pack: either you won't be able to get your velocity high enough or you won't be able to get it low enough. I don't remember which it is.

I think that I might still have a spacer or two of them lying around for classic mags.
Hmm, i wouldn't mind one, but the thing that makes more sens is that you wouldn't be able to get it low enough, because it wouldn't be strong enough to make it have a low enough volume to regulate the air lower, unless i'm thinkign about it wrong.

[SocialD]

Hmm, i wouldn't mind one, but the thing that makes more sens is that you wouldn't be able to get it low enough, because it wouldn't be strong enough to make it have a low enough volume to regulate the air lower, unless i'm thinkign about it wrong.

Okay, now you are forcing me to think :slap::

The marker will require higher operating pressure with a spacer in there. If the spring pack isn't changed out, the higher operating pressure will not be able to be acheived. Therefore, the result would be lower velocity. A stronger spring pack will allow high pressure in the chamber and increased velocity at which point you have to "adjust" the reg piston to make up for the higher pressure....I think.