Bushmaster M4, bad fit.

[11Bravo20]

I bought a new Bushmaster M4 type carbine in may. I found after my first shooting session that I had aluminum bubbles showing through the finish on one side of the upper receiver. I sent the upper back to Bushmaster for them to check out. They replaced my upper with a new upper of the same. Now my new upper does not fit as well as the old one, it is loose fitting and I feel that it has too much play. Question is what can I do about it?

[AZ-Boog]

ummmm. talk to Bushmaster??

they have some of the best customer service in the business.

They will make it right. Give them a call.

[A_Swede_17_1911]

I would talk to the factory, but on the m16 ar15 family of rifles sometimes there is a slopy fit between the two recivers, but not really that common on new rifles, but you can get a wedge that fits between the two recivers and tightens them up, its in the bushmaster catalog.

[ProfMoriarty]

Sloppy upper to lower fit doesn't effect acuracy, but it's a PITA to have an expensive AR that rattles.

The Accu-wedge mentioned above costs a couple bucks and eliminates upper/lower play.

[DJ Niner]

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)...;g