Fortunately 30 carbine is a .308 diameter bullet so you can load them. You loose the ballistic gains that many people like and when you go with a really short cartridge other feeding problems may show up. In the long run with an AR you will find that sharp pointed cartridges that are almost the maximum OAL function the best. I say this after loading up quite a few 180gr round nose 300/221 cartridges but at .13 a round what can I say
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