Upper/lower tightness - does it matter?

[lymph]

If there's a tiny bit of play between the upper and lower on an AR, does it matter? Seems to me that if the bolt, barrel, and sights are all lined up on the upper, it wouldn't make any difference if the lower weren't completely tight against it. Any insight?

[FALna45]

i agree that the 'play' is no detriment.
i also use an accuwedge which is an inexpensive fix for the slop. i've heard F/A shooters advise against the wedge; purporting that the resultant snugness in combination with the high # of cycles an F/A sees cause wear on the pin holes. just what i've heard.

[CIAHitman]

A tiny bit of play is normal. Too much slop can cause you to cant the rifle and could potentially make you miss your shot.

[DJ Niner]

Copied from another thread I responded to in the BRC; forgive me if you've aready read this, folks:

I have Accu-wedges on all my ARs, even though they are put together fairly tight; I REALLY HATE a weapon that rattles when I handle/carry it.

Having said that, a friend and I did a test many years ago with 4 military M16s; we picked out two that were loose as a goose, and two that were new-issue and VERY tight. We accuracy tested them with ball ammo, and one of the loose ones shot the tightest groups, repeatedly. The other loose one and one of the tight ones were about tied for second, and the last tight one was a DISTANT third (groups three times as large as the best-shooting rifle). Results were the same for both shooters; group size varied from weapon to weapon for both shooters, but the relationship between the 4 rifles (best to worst) didn't change. After that, I didn't worry as much about tightness/looseness of the upper's fit; if it shoots well, then it shoots well. If it shoots poorly, then you should find some different ammo and try again, but don't let a little noise convice you that it can't be a good shooter.

(Said the guy who HATES rattling weapons)...

[Shady]

The play between upper and lower has no effect on accuracy. Some folks get in a twist about it and like to snug them up with an accuwedge or similar treatments.

I don't mind a little wiggle, myself, but if the play makes you crazy, do something about it. There's something to BELIEVING the gun will be accurate that helps some people.

[lymph]

Interesting. I wonder if the stress/pressure the wedge puts on the upper effects accuracy. Maybe having it a little loose is sort of like "floating" the whole upper.

It probably shouldn't matter unless the wedge shifted somehow between shots.

I'm not going to bother with a wedge.

[ThinkOfTheChildren]

Originally posted by lymph
Interesting. I wonder if the stress/pressure the wedge puts on the upper effects accuracy. Maybe having it a little loose is sort of like "floating" the whole upper.

It probably shouldn't matter unless the wedge shifted somehow between shots.
It still shouldn't matter. The bbl, the bolt, the chamber, the sights, etc etc etc: they're all on the upper. If you could theoretically clamp the upper of an AR to something so tight that it could never move, you could stand there and rattle the lower all day, wedge it against the upper, whatever you wanted, and the group shouldn't change.

Rattle shouldn't lose you accuracy, nor should it help it. It's just unrelated.

Of course, if you did it the other way around: only holding the lower still, then of course moving the upper around is going to move point of impact around, but it will also move point of aim around. Properly aligned sights won't lie, no matter the rattle.