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Posted: 11/30/2011 8:53:41 AM EDT
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I'd love to build an AR but I want to have a 5.56 and .308. My question is can you simply build a caliber-specific upper and use the same lower for both calibers? My perseption is this isn't doable as the magazine well would need to be different to accompdate both sizes.
Are there any lowers that could accomodate multiple calibers? If so, what's the range of sizes? Thanks! |
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Or he can wait for the new Colt .308 which will take 5.56 uppers...
http://www.ar15.com/forums/t_2_29/199659_SP901____CM901_pics_news_and_info_only____UPDATE_PAGE_5___.html |
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Quoted:
Or he can wait for the new Colt .308 which will take 5.56 uppers... http://www.ar15.com/forums/t_2_29/199659_SP901____CM901_pics_news_and_info_only____UPDATE_PAGE_5___.html Yep. Looks like an interesting idea. |
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Well one way to do this is using the 7.62x39. It is not .308winchester or 7.62x51 but still is 7.62. That's like saying .22LR is just like .223 - because they are both 22 caliber. World of difference in the performance envelopes. I realize that but in a 5.56 lower setup if he wants a 30 cal round it is an alternative. Never said though that the 7.62x39 and 7.62x51 had equal performance. It is kind of unfair to compare 22LR to .223 one is centerfire and one is rimfire the two I mentioned are both centerfire just one in intermediate. |
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It is kind of unfair to compare 22LR to .223 one is centerfire and one is rimfire the two I mentioned are both centerfire just one in intermediate. Not really unfair - in my comparision you have one round which is inexpensive, comparitively low recoil, with comparativley limited range and terminal performance. That pretty much sums up the 7.62x39 vs .308 comparison - low cost/low recoil or higher recoil/performance. |
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Why hasnt anyone mentioned the Colt SP901? Colt has made a lower receiver that will accept BOTH 5.56 and 308 uppers. You can use any milspec AR15 upper, but the 308 will have to be from Colt im sure. They are not out yet, but will be available soon enough.  Did you read the thread? It had already been mentioned several times.
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