PSA upper with different bolt carrier group?

[SpringfieldArmoryXD]

Palmetto state armory is currently out of BCG's with any of there orders. I was wanting to order an upper from them, but don't want to see how long it takes for them to get BCG's back in stock.

If I got a BCG from another reputable company and stuck it in the PSA upper, would I need to get it checked for head spacing?

 

[Girodin]

If you do a google search of something like "AR15 BCG headspace" you will find a lot of threads on a lot of forums concerning this topic.

The general consensus seems to be that you most likely would be fine simply installing a quality BCG, but that checking head space is the better, wiser thing to do. Furthermore given that go no go gauges are relatively cheap there is no real good reason not to simply check it and be sure.

Many people who always check, report having never found one that was a problem, but nevertheless they still check them all.

 

[gotigers]

Head space shouldn't be an issue with a new barrel and a new bolt. I have never had an issue with head spacing. I have mixed and matche several AR barrels and bolts. None of the ARs i've built had a single issue. This is a very common practice. This is the same advice i have been given and read the same advice given to others for years.

The problem comes after use. The more shots, the more the two mating parts wear.

If either has been used for more than a couple hundred rounds, i would get the head space checked.

I wouldn't worry about it if both are new.

Edit: I would make sure to get a MP/MPI stamped bolt, regardless.

Edit: If i were getting a new precision barrel like a Krieger, i would get a matched bolt.

 

[Mobuck]

While there's always the chance that tolerance stacking will result in excess headspace, I've personally assembled 10 or 12 uppers using name brand nonmatched BCG and haven't had any issues. I have had a couple that seemed too tight but none that showed excessive headspace.

 

[a-sheepdog]

I would not worry too much, I have assembled more than a few AR's and none of them had any issues with head space, though I do check to ensure that the headspace is correct before it leaves my hands. Make sure that the gas key is properly staked.