Is this safe?

[url]http://www.ar15.com/forums/topic.html?b=3&f=118&t=168668&w=searchPop[/url]

Thanks for the link.

From what I read:

It's OK to swap the carrier out, but not the bolt after a while of shooting with that system.

If you buy an upper without b/bc, and you get the b/bc together as a set separately, the new bolt will start a pattern of wear with chamber that should be messed with. In other words, dedicate whatever b/bc you buy to that upper.

And, this is really my question:

Can I buy a DPMS b/bc for a RRA upper? BM b/bc for a DPMS upper? Etc.

Thanks.

The carrier wears into the receiver just as bolts do.  Changing the bolt is okay but it will accelerate the wear, just like changing carriers, and the shooting characteristics may change because the bolts will vary in headspacing.  At any rate, it's better to have a dedicated carrier/bolt assy for each upper, and handier too.  And yes, you can buy one manufacturers assembly for use into another.  All the parts are supposed to be made to the same specs - they should all interchange without problem unless you bought an improperly manufactured part, or from a crappy company that didn't make it right to specs in the first place but sold it anyway.

By the way, there isn't going to be any major problems swapping B/BC assemblies after you fire a while, it's just not recommended.  Carrier assy's get swapped all the time, it's just going to make your upper ever so slightly looser (internally) doing so, cause a fraction more wear.  Military does this all the time, they don't mate carriers and bolts with specific weapons - of course it accelerates wear though.  Almost all bolts will headspace just fine, but some fear changing bolts without checking headspace first. It's safer, but generally unneeded.