I will. it may take a while to track it down. Really not sure what to try next. I think i will put the questionable lower on my other upper and see if it throws the POI off as well. Maybe i have an out of spec lower although it seemed to lock up good.

Well. I changed the buffer itself and it did the trick, i had the same POI as my carbine lower. They were both rifle length buffers but one was heavier than the other. Hard to believe that it made that big of a difference. Wish I had more info. I know the heavier one was an ARStoner the other I think was an aero.

Just catching the thread now but yes you got problems with your buffer/spring and the problem is likely there. Have you ever considered a captured buffer? Your going to be able to get rid of the whole buffer retainer idea,you can run them in rifle/carbine length tubes with the same lock time/consistency and can also be easily swapped from gun to gun when you switch uppers. Once you try one you wont go back to the spoon over the spring twang.

SOUNDS LIKE YOU ARE TRYING TO RUN A CARBINE LENGTH (sorry) gas system with a rifle butt stock, maybe an issue, plus you need to get the buffer retainer fixed so it stays put!!

with a properly sized and located carbine gas system, thats just a phrase used to describe that gas port location. it has nothing to do with pairing a stock with it.

please consider that a standard a2 (or similar) style fixed stock "rifle" buffer = 5.2 oz. a "carbine" H3 buffer is 5.4oz. the length difference -5.900" vs 3.250" - is to accommodate the buffer tube length difference.

they even sell nylon spacers you can put in behind a carbine buffer to use them in a rifle length fixed stock buffer tube.

in theory - the buffer weight should only effect lock time and overall recoil impulse. the bolt in an ar-15 rifle will not even start to move until well after (relatively speaking since we're dealing with MS here) the projectile has left the barrel.

which makes it even more wild in this case that swapping out the buffer seems to have corrected the issue.

were they otherwise dimensionally the same? should both be 5.900" long.

have you weighed them out?

those would be to very interesting data points to have.


this really has me scratching my head because, in theory at least, changing your buffer should have absolutely zero effect on POI/accuracy in general since a closed bolt is a closed bolt, and the AR system is designed to not have the bolt start moving until the bullet has left the barrel.

does beg to wonder if for whatever reason you were getting some wierd bolt tilt, or excess bolt speed causing the projectile to hit on something during feeding and either setback a bit, or tilt just a little so that it was coming into the rifling at a bit of a cant because of the deformation on chambering.