Posted: 3/2/2012 3:56:25 AM EDT
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What is the difference in the lowers of a Colt AR that has "cal .223" as opposed to those that has "5.56" in their roll marks?
I have a 6721 and the lower in engraved with .223 but the barrel is 5.56. So what is the difference in the lowers? |
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What the gun is chambered in will be marked on the barrel. Colt sometimes puts 5.56mm and sometimes they put .223 on the lower. It just depends on the model. All semi-auto Colt lowers are virtually the same as long as they are produced during the same time frame. The only differences are roll marks. Also Colt does not engrave lowers, rather they roll mark them.
So an older R6601 will have large FCG pins and a sear block in it, while a new MT6601 will have milspec .154 FCG pins and a sear web instead of a block. Both guns however are chambered in 5.56mm, which would be marked on both barrels. So in the end, if you are trying to identify what a Colt gun is chambered in, always look at the barrel markings. |