Putting Old BCG (Bolt Carrier Group) In Brand New Upper: Would That Cause A Problem?

AR/M4 AR General Discussion
1

I have a 12 year old Noveske 16" (overall) upper.
It works great and has 6,000 rounds through it.
The BCG is in perfect shape. The bolt has been proactively serviced with a new:

  • BT-08 Extractor Spring
  • BT-03 Extractor Pin
  • BT-08-OR Extractor O-ring
  • BT-01-3P 3 Pack Gas Rings
    At 5,000 rounds.

I have a Noveske Gen 4 Upper (16" Overall) on order that I expect in a few months.

The reason for the new upper is not relevant.

Is there any harm in putting the old BCG in this new upper???

It has so much more life left.

I want to preserve the new BCG as long as possible.

Please share you thoughts.

1 Like
2

Should be ok. The maintenance isn’t relevant. It’s the wear on the rear of the bolt lugs and the galling on the inside of the mating surface in the barrel extension that cause headspace to “grow”.

A 6k bolt in a new upper might have a tiny bit of extra headspace compared to a new bolt, but no likely enough to worry about.

2 Likes
3

I would think it woild be just fine. I’ve done a fair amount of this time of switching with no ill results.

2 Likes
4

O man, that’s gonna look ugly, old BCG in a new upper. As long as go no-go is ok and it runs smooth, no issue.
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5

It’ll just be “broken in” already. Send it!