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Posted: 4/27/2011 6:51:15 AM EDT
I have a M&P bcg and a colt upper reciever. Will the M&P function correctly and safely in the colt upper? Sorry if its a dumb question, fairly new to all this. Thanks
Link Posted: 4/27/2011 6:57:59 AM EDT
Function- Yes.
Check your headspace before firing to ensure safety from using mismatched parts.
Link Posted: 4/27/2011 7:13:33 AM EDT
Originally Posted By a308garand:
Function- Yes.
Check your headspace before firing to ensure safety from using mismatched parts.

+1, and welcome to the forums!
Link Posted: 4/27/2011 7:51:04 AM EDT
If you have new parts or parts with relatively few miles on them then there is no need to check head space. It won't hurt anything if you do, however. Generally there is no problem swapping parts as long as they are in spec which you will find out in short order. Enjoy.
Link Posted: 4/27/2011 9:27:25 AM EDT
So - anyone gonna tell him HOW to check headspace?
Link Posted: 4/27/2011 10:10:30 AM EDT
I didn't know M&P made BCGs. I didn't realize M&P made any AR-15 parts.

It has been said that M&P ARs were made and serviced by Stag/CMT.
Link Posted: 4/27/2011 10:20:45 AM EDT
I just read the OP again.

OP: Are you talking about a stripped upper receiver or a complete Colt barreled upper?
Link Posted: 4/27/2011 2:00:48 PM EDT
I have a question. I am kinda new to all of this too. If I have a F/A bcg, do I need a heavier buffer? It is installed in a 16" car with a mid length gas system.
Link Posted: 4/27/2011 4:52:44 PM EDT
Its a bcg out of an M&P 15. and it is a colt upper with gas tube and barrel....
Link Posted: 4/27/2011 7:36:44 PM EDT
You should be fine. If you're worried about headspace, just order a set of gauges from Brownell's or Midway.
Link Posted: 4/27/2011 8:55:44 PM EDT
You should be well served with an H buffer.

Originally Posted By commercialcutter:
I have a question. I am kinda new to all of this too. If I have a F/A bcg, do I need a heavier buffer? It is installed in a 16" car with a mid length gas system.


The best option for checking headspace is the 5.56 NATO FIELD gage made by Bill Ricca: http://www.billricca.com/collectors_corner.htm

About a quarter of the way down the page, its noted as "M16 Maximum Headspace Gage"

Link Posted: 4/27/2011 9:31:00 PM EDT

Out of the millions of civilian AR-15s and the millions of military M-16s there are only a hand full of accounts of "supposed" headspace issues. Unless you have several thousand rounds on that BCG you are nowhere close to having a headspace issue. I garantee your bolt lugs will break before you ever get to that point! In the military bolts get swapped all of the time during batch cleaning. I've never seen a M-16 upper or bolt with matching numbers. If it were an issue they would be marked like a bolt action rifle.han

What part of tight tolerance and total interchangiblity are we missing. The only issue arises with a chamber being improperly reamed (which is quite rare). That is what the headspace gage is for, not the bolt. Never heard of a Colt chamber being out of spec from the factory. After millions of uppers produced you'd think they'd have it right. Ever hear of a bad Colt, Spikes Tactical, Sabre, BCM or FNMI?
Link Posted: 4/29/2011 3:41:37 PM EDT
[Last Edit: 4/29/2011 3:46:54 PM EDT by Direct-Drive]
Originally Posted By commercialcutter:
I have a question. I am kinda new to all of this too. If I have a F/A bcg, do I need a heavier buffer? It is installed in a 16" car with a mid length gas system.


Check your PM's (upper left)


Heavier than what ?
What ammo ?
There is a combination of elements that determine the best buffer for your particular rig.

Sorry about the hijack, OP.
Link Posted: 4/29/2011 4:12:19 PM EDT
[span style='font-weight: bold;']Originally Posted By altopwescap:[/sp . Ever hear of a bad BCM ?


Yes

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