Please HELP me on my M&P15!!

[AJM0617]

Hello guys, I have a Smith & Wesson M&P15 lower receiver with a Bushmaster Heavy Barrel stamped with 5.56 NATO. but my M&P15 lower receiver doesn't say anything about caliber.. I have been shooting it with .223 Rem. but I recently purchased a bunch of 5.56 x 45 NATO.. So, is it okay to shoot it with 5.56 NATO? if not, what do I need to replace to make it able to shoot 5.56 NATO?

please let me know..

thank you

[cobravenom39]

Lower has nothing to do with 223 or 556. Only upper and barrel. You're fine.

[Iraqgunz]

This is a rather elementary question. Have you tried your Google-Fu? You should be ok, but Bushmaster chambers have been known to be a bit tight.

I suggest you simply try and see if you have any FTE or anything else.


Hello guys, I have a Smith & Wesson M&P15 lower receiver with a Bushmaster Heavy Barrel stamped with 5.56 NATO. but my M&P15 lower receiver doesn't say anything about caliber.. I have been shooting it with .223 Rem. but I recently purchased a bunch of 5.56 x 45 NATO.. So, is it okay to shoot it with 5.56 NATO? if not, what do I need to replace to make it able to shoot 5.56 NATO?

please let me know..

thank you