Interchanging bolt carrier assemblies

brushbuster

I have a Bushmaster 5.56mm in a standard heavy barreled 16" configuration. I have a red-dot scope mounted on the carry handle and a high-powered scope mounted to a riser. I have been exchanging the carry handle/red dot set-up and the riser/high-power set-up to suit the style of shooting I am doing, but, while close, the sights do not return to the zero I want. I want to get another upper assembly and exchange uppers rather than sight systems. What are the pros and cons or even dangers of exchanging the bolt carrier assembly between the two uppers? Will this plan stop me from having to re-zero every time I change systems? Money is an issue, or I would just get a second complete upper. Thanks for your advice.

Brushbuster.

p3skyking

A change of bolt carriers should not be a problem. Milspec parts are just that, milspec. Even the bolt should be okay. If the carrier runs forward enough so that you can close the weapon, it's obviously okay.
This isn't rocket science.

brushbuster

p3skyking- Your post illustrates what my thinking has been on this subject. Bushmaster touts the ability to interchange parts as the "beauty of the bushmaster weapons system," in its catalogues. But my manual, on page 39, contains a warning that, "Bushmaster does not recommend the practice of swapping bolts between different rifles. Doing so could result in damage, personal injury or death."

This is why I am asking the question. Which literature do I believe?

gunphreak

That is a peculiar warning. There are only three reasons I would suggest a word of caution, but at this time, I don't know specifically what their warning is there for.

1. Someone isn't playing by the milspec rule.
2. Because they suspect someone isn't playing by the milspec rule.
3. Because they do not want you buying other manufacturers parts.

Most likely, the reason is #3.

I'm here to tell you, I have an ASA lower receiver and upper receiver, an Armalite bolt carrier and bolt *'y, as well as full lower parts, and an M4 16" barrel whom I have no idea who built it, and it runs great. I put the thing together in an effort to save money, and I did just that. I've not seen another 16" rifle that does as well as mine on the range, and it has proven to be 100% reliable (with the exception of the time the carrier key come unstaked, which was not the gun's fault, it was my fault.

BHAVIN

It is commonly done and doesn't pose a problem as long as you are using Mil Spec parts. I believe that this "Don't do this" literature is a carry over from the military as well as possible liability issues.

brushbuster

Thanks for your replies. I intend to get a Bushmaster V-match upper w/out the bolt and carrier assembly, and run the Bushmaster bolt and carrier assembly I already have in it. Using the same manufacturer's parts seems safe enough, especially since Bushmaster DOES use this as a selling point. Still, the warning will make me a little uneasy.................
But then again, the replacement/spare bolts and assemblies we can order are NOT specific to the particular upper configurations we might own. I am probably being paranoid, but thought it was worth asking about. Thanks again!

Brushbuster

nmyers

The potential problem is not with the bolt carrier, it is with the BOLT.

Yes, most parts on AR-type rifles are interchangeable. However, as with many rifles, the bolt should not be changed without checking headspace. Excessive headspace can be caused by improper barrel installation and/or wear on the bolt lugs. Failure to check headspace may result in catastrophic failure of the rifle.

You need to buy AND READ at least one reference book. I suggest "The AR-15 Complete Owner's Guide" by Walt Kuleck with Scott Duff.

Neal

"Just because you're paranoid, that doesn't mean that they aren't out to get you."

tig

Gezze, bite the bullet and get a bolt and carrier for each upper, I have a C3 M16 i have 3 different uppers for, each bolt and carrier develops its own minute fit to each upper,they will stay accurate longer,swapping only aks for eventual slop and wear.