Heavier bullets and the AR platform in .308?

TonyAngel said:

I was just wondering. With a bolt gun, I’ll fire form my brass to the chamber and when reloading only size enough to bump the shoulder and tighten the neck and not crimp.

This usually helps with achieving the best accuracy but, I don’t know that you can do this and still feed from the magazine with an auto.

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Even with my bolt guns, I used body dies set to .001” head space, followed with a neck die. Seating with a micrometer bench-rest seating die, I made some very good ammo, with almost zero runout.

you need to make sure you bump the shoulder back enough

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+1

Unless one has moved into the ulta-precise/OCD crowd, Gas Guns require (if you're smart) full-length resizing.
(Kiss the brass off a bit earlier, but that's the cost of reliability. )
From a practical gas-gun accuracy stand-point, not much effect.

I've heard good things about the ability to fine tune cycling with the adjustable gas block. One suggestion was to start with lightest bullet and record the amount of adjustment for each weight. That way you could set it accordingly on the spot.

Trey Veston said:

I've been fortunate in that all of my ARs have ran flawlessly out of the gate so never had to adjust anything. Never had to research gas block adjusting, so may have to brush up on things.

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I didn't know about them till a guy at the range told me. They take all the slap out of the cycling making recoil not beat on the gun. Puts better gas pressure effecincy behind the bullet. And as stated, if he changes bullet weight he knows just how much turn of the adjustment it takes. It really smooths it out.

skeeterfogger said:

I've heard good things about the ability to fine tune cycling with the adjustable gas block. One suggestion was to start with lightest bullet and record the amount of adjustment for each weight. That way you could set it accordingly on the spot.

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Adjustable gas blocks are mostly used as band-aids for overgassed guns. If you want to fine tune, you can do that by changing buffers. The only real use for adjustable gas blocks is when you're running suppressed. If your action is beating itself to death, it just might need a band-aid, though. The adjustable units are kind of a pain in the but to adjust once the free float tube is on. Eh, if you use something "tactical" or just drill a hole, I suppose you could adjust as wanted.