you should be fine with a std lower.
I have been looking into buying an AR but I don't want one that shoots .223s too high priced for my bank acct.. I have an AK-74 that shoots 5.45x39 ammo (that I have plenty of), and I see that I can buy an AR upper in 5.45x39 here.
Product: M&P15R Upper Receiver Assembly
My question is if I buy this upper, will any lower work with this upper or does it need a specal lower just for that cal. round?
Yes it works with a standard lower and includes a heavier hammer spring for the surplus 5.45 ammunition. You might want to stay with using commercial non corrosive ammo if you can find it. A lot fouling gets blown back in an AR.
And I hear it is a real pain to clean.A lot fouling gets blown back in an AR.
Thanks for the info.
Get one of the gun rugs, it's a piece of neoprene that is cut to fit in the lower. It will keep alot of the fouling out of the lower.