can I put a different upper on the Sports lower? My current chamber is 5.56 but I may try a flat rail and choose some iron sights. I use the A2 but want to try a flat platform without the BS of removing the front post- opinions?

thanx-

Yes, you can put a different mil-spec upper on your Sport lower, but why? I don't understand what you mean by "flat rail", as the sport is already a flat top upper. If you are wanting a rail system, there are drop in available that would still utilize your front sight. Or, you can either shave it down or remove and replace with a low profile gas block and install a free float quad rail or tube.

Any of these solutions are cheaper than buying a whole new upper.

I think he means an upper with a railed gas block. I had one put on my Sport and the changed it back.

I get it. He wants to keep the stock upper as is, because he likes shooting it. He then wants to get an additional upper he can experiment with. OP, any mil-spec dimension upper will fit.

__________________
-John

Big John is rite! Thanx, to JLduke- why did you go back? And my thank's to all who take the time to help with a new guy.

redsox17,

Don't be afraid to try removing the A2 front sight post. S&W uses tapered pins that need to be driven out right to left. It takes a bit of force to drive them out. I'd been itching to install a free float rail on my 15-Sport, but was hesitant to try it. A small LGS nearby showed me how.



Troy 15" Alpha Rail. The small LGS had it for a good price. I didn't have to replace the barrel nut.

YHM Low Profile Gas Block.

Front and rear Troy folding battle sights.

If you're looking for complete uppers, there are various places to buy a complete upper. I live local to RGuns. I've built a rifle using one of their complete uppers. I have two friends who built rifles using their basic upper. All three function perfectly.

RGUNS - AR-15 Upper Receivers -5.56mm: 16 Inch - Heavy Barrel



This is my budget build: a Delaware Machinery lower and an R-Guns upper. I prefer shooting iron sights over red dots. I have this one set up as an iron sight only rifle.

__________________
-John

I wouldn't replace the sport upper unless you want a HBAR varmint rig or something.

My sport is VERY accurate. It is significantly more accurate than any 1:7 "mil spec" upper I've ever had.