Mark01 Posted May 4, 2006 Share Posted May 4, 2006 A JP adjustable gas block was one of the givens to be included on my new build. However it seems as though it is one of those things that is "nice" to have but not really used. From what I've read and been told it seems most are running the JP full open. How many are actually adjusting their JP gas block or running it full open? Link to comment Share on other sites More sharing options...
MikeFoley Posted May 4, 2006 Share Posted May 4, 2006 Adjusted per instructions, added for reliability, and haven't changed since. I notice a big difference when I shoot a full gas gun. Link to comment Share on other sites More sharing options...
George Posted May 4, 2006 Share Posted May 4, 2006 I adjust miine according to the JP instructions. Close till it won't lock back, open till it will, add a half turn and leave it. I went 3/4 turn for a tad more oomph and have stayed with it since I initially tested it. The difference when wide open to set right is definitely noticeable. This reduction of sight dance is what the JP Lo-Mass Operating System was designed for. IMO, why would you want to circumvent half the impulse reduction that is available for a tad more operating reliability that is mostly a worry rather than a reality if you actually clean the system. The adjustable gas block concept really is only useful with the lightened carriers as the full on gas systems supply the correct gas impulse for the full weight carriers to operate in THEIR design zone. If you are not using a lightened carrier and matching buffer/spring system, then you should run an adjustable gas block pretty much wide open. Link to comment Share on other sites More sharing options...
sfinney Posted May 4, 2006 Share Posted May 4, 2006 I run my JP Block adjusted as per instructions. It is definitely lighter recoiling than when set "full open". And I have a Mil-spec carrier, not a lightened one. YRMV. Link to comment Share on other sites More sharing options...
get2now Posted May 4, 2006 Share Posted May 4, 2006 I had nothing but problems with mine. Eventually it had to be opened up (drilled out) and I had to cut a couple coils off the buffer spring too. Apparently I may be the exception, but when I had my last rifle built I just used a stock gas block then had the front sight cut off. That one works flawlessly. YMMV Link to comment Share on other sites More sharing options...
BigDave Posted May 4, 2006 Share Posted May 4, 2006 I run my JP Block adjusted as per instructions. It is definitely lighter recoiling than when set "full open". And I have a Mil-spec carrier, not a lightened one. YRMV. +1 Link to comment Share on other sites More sharing options...
George Posted May 4, 2006 Share Posted May 4, 2006 I run my JP Block adjusted as per instructions. It is definitely lighter recoiling than when set "full open". And I have a Mil-spec carrier, not a lightened one Can't really argue with results! In truth, there is enough gas surplus in the standard system to run the bolt carrier full throw in all conditions. The only possible downside here from removing some of that extra impetus is that it closes up the operating window. It might just make the gun need to feed on the ammo that it was actually adjusted with instead of a wider range of ammo, then again it might not ;-) In other words, when you tune down the gas system on a standard weight carrier, you narrow the reliable operating range of the overall system to make the gains. The lightened carriers do not really have a narrowed operating window per se' because they use a spring/buffer designed to put them smack in the middle of a design sweet spot again, just like the full weight carrier/spring/buffer system working with a full on gas pulse. YMMV. Link to comment Share on other sites More sharing options...
Zak Smith Posted May 4, 2006 Share Posted May 4, 2006 Always ran mine full open, with a LW carrier or regular one. Link to comment Share on other sites More sharing options...
Religious Shooter Posted May 4, 2006 Share Posted May 4, 2006 On one of my uppers I run it fully open. With this particular upper I use a variety of rounds --- reloaded 69 SMK and Full/low power 55's, various factory ammo (Wolf, Winchester, Remington, etc.). On another upper I adjusted it as directed. For matches I only plan to use one load (reloaded 55's) on this upper. I'm sure it will be iffy if I use downloaded ammo during practice. But during practice I don't really care if it jams. I run the MSTN/YM lightened carrier. For the life of me I can't tell a lick of difference with the gas block adjusted high or low when run with 55's. Don't know if the full power 69's or 77's make a difference or not. I guess less gas through the gas tube could mean better velocity and better upper/bolt/etc. life (less wear and tear). So I personally would still get the adjustable gas block on any game upper that I buy in the future. I wouldn't use it on an upper that may be used socially. Link to comment Share on other sites More sharing options...
Mickster Posted May 4, 2006 Share Posted May 4, 2006 Adjusted mine per the instructions till it just locked back and then gave it 3/4 turn. However, I did this with the lowest powered factory 55's I had, which are Wolfs. This way it should run reliably with everything else. Probably not the ideal set up for an adjustable system where the goal is maximum recoil impulse reduction. But it has worked perfectly. Even when switching ammo brands, weights and types. Link to comment Share on other sites More sharing options...
sfinney Posted May 4, 2006 Share Posted May 4, 2006 I run my JP Block adjusted as per instructions. It is definitely lighter recoiling than when set "full open". And I have a Mil-spec carrier, not a lightened one. YRMV. Guess I should say I set it for one type of ammo, and only use that ammo in that rifle. Works 100% in those conditions...... but I guess if I did have to change ammo type, I probably would have issues. Adjusted "full open" works with a wider variety of ammo, obviously. Link to comment Share on other sites More sharing options...
norbs007 Posted May 4, 2006 Share Posted May 4, 2006 (edited) Used 140-145 PF loads and adjusted it while the gun is dirty. Opened it to where it just locks back and another half turn. Runs great with factory ammo and 155 PF loads, gun barely moves. Just don't forget to loctite the screw, the damn thing closed up on me twice when I first got it. Edited May 4, 2006 by norbs007 Link to comment Share on other sites More sharing options...
D.Hayden Posted May 5, 2006 Share Posted May 5, 2006 Norbert... Loctite, exactly what I was wondering.. Did you take Loctite out to the range that day? Probably a rookie question, how long do you have until Loctite sets, and if you loosen the screw, you have to reapply? Link to comment Share on other sites More sharing options...
George Posted May 5, 2006 Share Posted May 5, 2006 Use the Blue. It will set fine as the gas block cools after you set it. Don't apply it until the gas block has cooled to hand touchable. If it's walking the adjust screw as you shoot and adjust it, leave the hex wrench in the screw with masking tape holding it in place and still as you shoot and adjust. This also gives you a precise clocking reference for the 1/2 to 3/4 turn bonus play ;-) Now that mine has loctite in it, it takes gorilla torque to change the setting and I have not had to re-apply it for almost 4 years now :-) Link to comment Share on other sites More sharing options...
norbs007 Posted May 5, 2006 Share Posted May 5, 2006 Norbert... Loctite, exactly what I was wondering..Did you take Loctite out to the range that day? Probably a rookie question, how long do you have until Loctite sets, and if you loosen the screw, you have to reapply? Like what George said. I never touched mine ever since. Link to comment Share on other sites More sharing options...
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