Is it dangerous to share a bolt and BCG between uppers

Discussion in 'Rifle Country' started by kd7nqb, Feb 17, 2013.

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  1. kd7nqb

    kd7nqb Member

    May 1, 2006
    Puyallup Washington
    Here's my dilemma I have bushmaster AR and love it. Now I want to get a .300blk upper for it.

    From my understanding I can use the same mags and same bolt and BCG for the .300blk. But some people seem very adamant that you should get a new BCG for each upper so the two wear evenly together.

    My question is how big of a deal is it really and are there any safety issues or is it only a wear issue if I shoot tens of thousands of rounds.

    My plan is basically to only use the .300 during hunting season.
  2. mizer67

    mizer67 Member

    Jan 19, 2012
    Your headspace could be a little on the loose side of "go", but you should be fine for the usage you describe.

    Worst case you'll probably rob yourself of some accuracy.

    You may want to get a no go guage just to be on the safe side.
  3. taliv

    taliv Moderator Staff Member

    Oct 23, 2004
    the carrier doesn't matter, only the bolt. bolts are wear parts. you should replace them with new ones every 5-10k rounds anyway.

    i the barrel/bolt was a matched set like you get from WOA or something i wouldn't swap it. but if it's a run of the mill part, sure, why not?

    i personally also wouldn't do it long term since i lube my blackout and 556 differently. but if it's just a temporary thing until you find a BCG in stock somewhere, sure
  4. briansmithwins

    briansmithwins Member

    Aug 1, 2005
    In theory it could cause increased wear of the barrel extension and bolt. In real terms, since AR bolts usually break between 10 and 20 thousand rounds, it probably won't make any noticeable difference.

    The .mil manuals prohibit swapping bolts and say to check headspace when replacing a bolt, so the 'correct' answer is not.

  5. madcratebuilder

    madcratebuilder Member

    Jul 15, 2007
    Northern Orygun
    Quotes from the 23&P Army manual.

    The above is printed in several locations.

    The manual goes on to state you can use a used bolt in a new barrel (BE) a used BE with a new bolt, but DO NOT use a used bolt with a used BE.
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