Head space advise


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barndweller
December 14, 2013, 07:43 PM
I have a old colt AR 15. I got it back in the early 90's. It was after the first ban and before the second. I got a 300 Blackout upper today. The bolt is not notched out like my old Colt. It was notched to go by the block on the lower to keep it from being full auto.
Would I be safe using the Colt bolt on the CMMG Blackout upper? A friend told me he would not.

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SilentScream
December 14, 2013, 07:50 PM
Bolts are relatively cheap. Do yourself favor and go buy a new bolt.

barndweller
December 14, 2013, 08:05 PM
The CMMG came with a new bolt but it won't work in the old colt lower because of the block above the sear. I'm wondering if it is safe to use the old colt bolt in the new CMMG 300 upper.

rcmodel
December 14, 2013, 08:10 PM
Yes, it would be safe.

But, the old bolt lugs are worn into the old barrel extension.

So, may or may not match perfectly in the new barrel extension and wear in evenly again.
So one or more bolt lugs my end up taking all the stress and crack prematurely.


Why not call CMMG and see if they can swap out your new bolt for a new cut bolt that will work with the old Colt lower?
I'm sure they have run into that before, several times over.

All they can say is yes they can, or no they can't.

rc

barndweller
December 14, 2013, 08:28 PM
Thanks RC. I'll try to call them on monday

rcmodel
December 14, 2013, 08:33 PM
BTW: I think we are talking about the Bolt Carrier.

Not the Bolt itself!!

Right??

It will save some confusion if you talk to them about the Bolt Carrier when you call CMMG Monday! :D

rc

barndweller
December 14, 2013, 09:23 PM
Yes RC Thanks

rcmodel
December 14, 2013, 09:52 PM
Another BTW:
You can put any new AR-15 bolt in your old Colt bolt carrier.

If you got a new bolt in the new bolt carrier of the new CMMG upper?

Just take that new CMMG bolt out of the CMMG carrier and use it in the old Colt carrier.

Now you got the new matching CMMG bolt in the new matching CMMG upper / barrel extension.

Sorry it took me so long to figure this out??
I was cornfused there at first!

PS: Just keep track of which bolt is which when you swap uppers.

rc

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