Seal between valve and body

[SockMonkey]

so mags being notoriously inefficient, one thing I noticed was that with each shot I could feel air coming out between the valve and body. I have a minimag valve with a lvl10 and a ULE body.

I wonder how much affect a seal could have there. I know hill has a mod for two quad rings on a lvl 7 tip. and said he got a 30fps jump.. maybe this would give a measurable jump as well. I don't know if I will be able to perform a test and compare before&afters but I think I might just try a o-ring to begin with.

I did manage to get an o-ring to fit, and it stops all noticeable air, but I have no means of measuring any affect it might have.

[SockMonkey]

here is a pic of what I was talking about, I dont know yet what affect, if any, this has had. But logically if the air cant go out here, then it has to go somewhere (hopefully out the barrel).



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[Ando]

You have to remember that tube isn't air tight. You still have the slit where the sear goes through and the hole where the sear hits the on/off to deal with.

[SockMonkey]

I was thinking about that (why I said 'hopefully down the barrel). IDK, this probably does little to nothing. but only testing will tell.

[hill160881]

Same with my mod, but I misplaced my crono this weekend and have yet to find it. If I get the orings to tight on the power tube it will reduce efficiency.

I tried to reduce the volume in an x valve but need to test the efficiency on it as well.

[hill160881]

I am going to have to admit failure on this as the only increase was about 10 fps. It looks like Rogue's results years ago are confirmed. The other thing I noticed was that the consistency was +-2 with the mod as compared to +- 10 without. It was also more accurate.

Next is to try the devolumizing of both an Xvalve and a clasic.

[TwilightG]

I am going to have to admit failure on this as the only increase was about 10 fps. It looks like Rogue's results years ago are confirmed. The other thing I noticed was that the consistency was +-2 with the mod as compared to +- 10 without. It was also more accurate.

Next is to try the devolumizing of both an Xvalve and a clasic.

I don't see how you can consider this a failure ...unless you were expecting some groundbreaking numbers, I'd say that the increased consistency in velocity was well worth the experiment.

For a pump-mag or classic-valve application, this mod might prove to be worthwhile, IMHO. I'd only rule out RT or E- setups because of the sheer amount of wear that high ROF could impose on these o-rings not to mention the increasing velocity of an RT valve.

[OPBN]

Was there an issue with O-ring wear or failure? If so, would using lube instead of oil help? After my first shot, my FPS is usually within 3-4 on my mags. I'd potentially be interested in a +-2.

[hill160881]

Not a total failure but I was hoping for a good 20 fps increase or more. O well.

After several hundred rounds the oring on the bolt was a bit worn but I could use a urethane oring to mitigate it. The orings on the power tube tip are several thousand rounds old and sitll look fine.


I want to do some more testing to make sure of the results before I add a devolumeizer to it.

I will try to maintain 6 bps without shoot down after devolumizing.

[BAZOOKA_Boy]

if you added an oring to the top of the power tube, cutting an oring slot into the inside of the body just infront of the sear slot give you a perfect seal with the other orings shown...and also to help reduce some wear on the bolt front oring, cut an oring groove in the body so it will seal when forward only, thay way its not drug forward and back. it will make a perfect seal, right now you are loosing some straight back in your face...and probably dont realize it...