Turning down gas increasing accuracy??

[arnie]

I was playing around with a bolt release that extends to the trigger guard so it could be activated by the trigger finger .Never did get it to make the bolt lock back on final shot so I removed it and put the stock one back in .I had played with opening the gas block to full open and never thought about setting it back down .Any way all of a sudden my accuracy was gone and it was acting like it had a bad crown .Three or four shots in group and then throw one 12 to 16 inches at 500 meters .I was going to try it with the muzzle break off but then noticed the gas block adjusting screw was way out so turned it to 1/2 turn out from bottomed and now its cycling ok and not throwing shots . I have it at 1/4 turn out now and will lock it down . Any one else have any thing like this happen ??

[blue109]

could it be the heavier recoil messing up your sight picture a few shots in?

[mrmackc]

It is a known that excessive gas leakage on a M1 Garand 3006 Will cause loss of accuracy. We used a gauge to measure the ID of the gas cylinder and replaced the worn cylinder to restore accuracy. I don't know why an AR10 or AR copy would be different

Edited December 24, 2014 by mrmackc

[N Jensen]

I would think that a slower cycling BCG would be more accurate in the long run. I have a new 260 cal and 26 inch barrel with a std gas port opening. Right now the BCG cycles so fast it can catch the empty as it goes fwd. I put the upper on hold until after the holidays is over. I plan on getting a hyd buffer and an adjustable gas block. I already have a std buffer spring, heavy, and an light one from a AR 15.

 

I was thinking of the AR 15 spring, hyd buffer, and turn the gas off and slowly open it until the BCG cycles, plus a half turn. Then shoot groups again.

[98Z5V]

If you have too much gas pressure, it makes the BCG/bolt want to start the unlocking process too early.  That can have a negative impact on accuracy.  Once that projectile is out/clear of the barrel, it doesn't have an impact anymore.  Up to that point, it's a possibility.

[survivalshop]

   Unless you have lightened BCG ,Buffer /spring , opening the adj. gas block adj. all the way up , would make it like you had a std . non-adj. gas block on . Like most of AR rifles out there . I would think it would be more the shooter than the rifle shooting oddly.

  Too much or too little gas pressure may cause function problems , but doubt it will change bullet impact or performance .

[Zebra644]

I wonder if a change in pressure due to the gas port causing a change in muzzle velocity thus affecting POI especially at that distance, But I find it interesting that it would be the last shot and not all of them. Maybe in some way it could also have screwed with your barrel harmonics to throw off that last shot? Those B.A.D. levers are nice I have one on my Spikes but I can live without it.

[arnie]

The trigger finger bolt release I was using is a Phase 5 . They take a regular bolt release and weld a steel arm on it because most 308 actions are so heavy ,there is no room to clamp the BAD type on .I have these on another side charger 308 and a 6.5 creedmoor and they work fine .They are noticeably heavier than just the bolt stop on its own .Im guessing because of the weight ,it cant move fast enough to operate . I recently bought a Tubbs weight to add to the carrier that's supposed to slow the cycling down .I haven't had time to try it out yet.

[98Z5V]

I like the Tubb CWS.  Have it in two rifles, for two different reasons, and it works very, very well.  <thumbsup>

[mrmackc]

I like the Tubb CWS.  Have it in two rifles, for two different reasons, and it works very, very well.  <thumbsup>

Do you have the Tubb buffer springs? I've thought about getting his cws to use with heavy long range 308 ammo. Probably get a new spring at the same time. The stock DPMS seems rough during BCG retraction and going in to battery.

[98Z5V]

I run Armalite buffer springs, except for one rifle.

[survivalshop]

    I have a Superior Springs 308 buffer spring ( Tubb's ) & whats good about them is , you can use it in Carbine or rifle systems . I'm about to use it in my 20" with rifle type stock( same spring that was in my 16" bbl. Carbine ) . The difference in the operation of the action in the Carbine was less felt recoil & The brass just ended up in a neat pile , about two feet from my feet & I mean a nice pile . 

  I plan to do Velocity testing in both rifles this year, just to see if there is a difference & I will use M80 , to do it in both rifles .