Re: Semi auto's, gas systems and accuracy
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rcw3</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Crossett</div><div class="ubbcode-body">I'm building an AR10 in 6.5 creedmoor with accuracy as a priority. It occurred to me that if I could close off the gas system so the carrier wouldn't cycle I might be able to eek a little more accuracy out of it when i'm shooting for groups, or at a long range match. So I started searching for an adjustable gas block that doesn't need a tool to change the setting.
This is basically all i've found
http://secure.adpay.com/clicknbuy.aspx?p...a2-0d1cb2a6ea28
Does anyone have experience with these gas blocks? If so how are they?
Is this even a worthwhile venture, or am I not going to see any appreciable gain from preventing the carrier from cycling? </div></div>
I do not know their product and the blocks they make may be beautiful and well made and what I say here has nothing to do with that company or their product.
I hate to give a "thumbs down", but if you are thinking that shutting off the gas system will enhance accuracy you will probably be in for a rude awakening and will likely find what happens is the reverse of what you expect going into it.
I have done a lot of testing over the years for accuracy shutting off the gas systems of AR-15's, AR-10's and LR-308's chambered in various cartridges and I never saw better accuracy shutting off a gas system, and almost always saw worse accuracy (along with a major change in point of impact and very hard cycling by hand)
1. With the gas system in operation, it bleeds off enough gas that it lessens the muzzle blast and recoil substantially, and the lesser recoil also translates into less stress on the push pin aluminum upper and lower receiver platform - and all of this is actually helpful to accuracy.
2. Shutting off the gas system almost always creates a change in your point of impact and different accuracy with the load involved (i.e. different harmonics, etc. with the system off vs on) and that can wreck havoc keeping good zeros and accuracy.
3. Adjustable gas blocks have a tendency to be inconsistent and somewhat unreliable over time (i.e. major pressures and hot gasses with particulate matter mixed in forced through a valve work it over for the worse real fast - kind of like sand blasting it and all nooks and crannies and moving parts) and for accuracy consistent gas bleed off and cycling is essential. The KISS principle is the best with gas systems - no valve - no moving parts - nothing to stick - nothing to freeze up - nothing to get clogged, etc.
4. All and adjustable gas block can do is close off gas coming into the system, and in many cases you see uppers over ported (which is bad for accuracy) just so the adjustable gas block can then throttle the gas flow back (not always precisely and consistently) to where it should be in the first place.
Anyway - that's my experience and analysis on the subject.
Robert Whitley </div></div>
That was a very comprehensive and convincing comment.
