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Posted: 11/26/2010 2:35:18 PM EDT
I have a new upper with about 70-80 rounds through it and I would like to change the BCG out for a BCM Ionbond BCG. I have been dying to see if it saves any time cleaning the BCG.  For those of you that have a lot (thousands) of rounds and had to switch a bolt, can you tell me about the wear on the barrel extension. I know it's bad ju ju to be swapping bolts, but I am guessing there is very little wear to the extension and it would be ok to do with such a low round count.
Yes, I will check headspace before firing. My major concern is about creating premature wear to the barrel extension because I am lazy. 
Any info would be appreciated. Thanks! |
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Really bad ju ju is putting a well used bolt in a brand new barrel. Most times a lightly used or new bolt to lightly used or new barrel will be fine but I still check the head spacing on my bolt to barrel matings regardless of what is new and/or used. I have checked about 10 new bolt/barrel combo's and I have only come across one new bolt that would not lock up on a "go" gauge in a brand new barrel ... if I had used that bolt without checking the head space first it might have worked but I am sure there would have been extra wear on something when the bolt was forced into the extension. As long as the head spacing checks out you shouldn't experience any extra wear on anything.
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Bad ju ju? When M-16 BCGs are batch cleaned they get swapped at random regularly. They're mil spec for a reason. If your mil spec upper had proper head spacing with the original mil spec BCG, why would a mil spec BCM BCG not have the same proper head spacing? What the heck would cause premature wear to the barrel extension in a new upper?
Any significant head spacing issue would be caused by mounting a new non chromed barrel. Many come needing head space adjustment. A BCG can not easily be adjusted. If you did it wouldn't be "in spec" anymore
I have yet to hear of anyone having headspace issues by swapping mil spec bolts. Especially BCM bolts, not to mention Colt or FN. |
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Quoted:
Bad ju ju? When M-16 BCGs are batch cleaned they get swapped at random regularly. They're mil spec for a reason. If your mil spec upper had proper head spacing with the original mil spec BCG, why would a mil spec BCM BCG not have the same proper head spacing? What the heck would cause premature wear to the barrel extension in a new upper? Any significant head spacing issue would be caused by mounting a new non chromed barrel. ]Many come needing head space adjustment. A BCG can not easily be adjusted. If you did it wouldn't be "in spec" anymore
I have yet to hear of anyone having headspace issues by swapping mil spec bolts. Especially BCM bolts, not to mention Colt or FN. Really .... So you think all "mil spec" bolts are exactly the same? I have news for ya ... they're not. And why does chrome or non chrome have anything to do with it? and how exactly do you "adjust" head spacing? please do elaborate on this. |
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http://www.ar15.com/forums/topic.html?b=3&f=4&t=315921
"You can’t really reset the headspace on an AR15 with a chrome-lined chamber. That is set when the barrel extension is installed on the barrel. If you have an unlined barrel, with short headspace, a gunsmith can adjust it by cutting the chamber deeper with the appropriate chambering reamers. If the headspace is long, or the chamber chrome-lined, the only option is to try a different bolt until headspace checks good, or you run out of bolts. Then it is time for a new barrel." I may be a bit naive but all BCM bolts plus bolts made by military contractors (Colt, FN, Advaced Ordnance and Tool Craft) are produced to exacting dimisions to strict tolerances as per military specifications. At least in my experience my several Colt and FN bolts are in spec diminsionally. |
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Quoted:
http://www.ar15.com/forums/topic.html?b=3&f=4&t=315921 "You can’t really reset the headspace on an AR15 with a chrome-lined chamber. That is set when the barrel extension is installed on the barrel. If you have an unlined barrel, with short headspace, a gunsmith can adjust it by cutting the chamber deeper with the appropriate chambering reamers. If the headspace is long, or the chamber chrome-lined, the only option is to try a different bolt until headspace checks good, or you run out of bolts. Then it is time for a new barrel." I may be a bit naive but all BCM bolts plus bolts made by military contractors (Colt, FN, Advaced Ordnance and Tool Craft) are produced to exacting dimisions to strict tolerances as per military specifications. At least in my experience my several Colt and FN bolts are in spec diminsionally. I know this but your statement.... Any significant head spacing issue would be caused by mounting a new non chromed barrel. Many come needing head space adjustment. A BCG can not easily be adjusted.
I understand that a chamber can be reamed and if it's chrome lined then that is not a good idea but it still can be done ... so what if the chamber isn't "short" and the bolt still does not head space to the barrel how exactly do you "adjust" the head spacing on a BCG? And in your own quote above it says to try "different" bolts .... now why would you try different bolts if like you say they are all "mil-spec" and exactly the same ... then wouldn't they all head space exactly the same? And why would using a non chrome barrel cause anymore head space issues than a chrome lined barrel? Please post your information on this .... because I really would like to see it. |
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