SW sport lower/BCM upper, Colt 6920 or Colt/BCM.

Eazyeach · April 3, 2017, 07:45 PM

I have a SW MP-15 sport lower(older model). Right now I have my BCM middy upper sitting on top of it. It's my go to rifle (range, crap hit the fan, home defense). Just a joy to shoot. 300 rounds at least with no issues.

My back up rifle is a Colt 6920. Haven't shot it yet, but I'm sure it's gtg.

I'm a little skeptical of the sport lower. I don't know if it is mil-spec or if that even matters. I'm wondering if I should keep my primary set up as is , switch to the Colt as my primary, or if I should slap the BCM upper on the Colt lower and have a sweet Frankenstein rifle. What say you?

CarJunkieLS1 · April 3, 2017, 08:19 PM

If its a forged aluminum lower, which I'm 100% sure that it is, just use it as is. No reason that a lower receiver from a well known and well respected manufacturer should have any problems. Keep your lower clean and the FCG clean and lubricated and enjoy.

Mobuck · April 3, 2017, 08:20 PM

"I'm a little skeptical of the sport lower. I don't know if it is mil-spec or if that even matters."

The upper attached to the lower w/o using a hammer? Then it's good enough. Why would you think the S&W not "mil-spec"(that's just a "feel good" term anyway)?

rickyrick · April 3, 2017, 08:22 PM

If you like it the way it is, keep it that way.

I doubt there's anything wrong with your lower.

Eazyeach · April 4, 2017, 06:16 PM

Thanks for the reassurance. I still might slap the BCM on the Colt just because I feel I'm wasting the Colt as a back up. I appreciate your time folks.

odugrad · April 5, 2017, 08:29 AM

What parts on the S&W lower are you concerned about failing? If you want, just replace those parts.

Ibmikey · April 7, 2017, 06:03 AM

One of my favorite rifles is a Sport lower with different furniture, Aero upper and Faxon LW barrel with 15" Faxon rail. The rifle is light and accurate, I can only guess it has had three or four thousand rounds through it and still knocks over clay pigeons at fifty yards from the shoulder and at 100 supported.
There is no way I would morph the Colt, get it out and shoot it! Three hundred rounds through my AR's does not even give one a workout, I try to make as many chunks of brick into powder on my shooting days, dirt clods and soda cans are also good fodder for a hungry AR.

View Poll Results: Which AR-15 set up
SW sport lower BCM mid length upper	4	57.14%
Colt 6920	1	14.29%
Colt lower BCM upper	2	28.57%
Voters: 7. You may not vote on this poll

April 3, 2017, 07:45 PM	#1
Eazyeach Senior Member Join Date: January 14, 2014 Posts: 706	SW sport lower/BCM upper, Colt 6920 or Colt/BCM. I have a SW MP-15 sport lower(older model). Right now I have my BCM middy upper sitting on top of it. It's my go to rifle (range, crap hit the fan, home defense). Just a joy to shoot. 300 rounds at least with no issues. My back up rifle is a Colt 6920. Haven't shot it yet, but I'm sure it's gtg. I'm a little skeptical of the sport lower. I don't know if it is mil-spec or if that even matters. I'm wondering if I should keep my primary set up as is , switch to the Colt as my primary, or if I should slap the BCM upper on the Colt lower and have a sweet Frankenstein rifle. What say you?

April 3, 2017, 08:19 PM	#2
CarJunkieLS1 Senior Member Join Date: October 1, 2013 Posts: 686	If its a forged aluminum lower, which I'm 100% sure that it is, just use it as is. No reason that a lower receiver from a well known and well respected manufacturer should have any problems. Keep your lower clean and the FCG clean and lubricated and enjoy.

April 3, 2017, 08:20 PM	#3
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	"I'm a little skeptical of the sport lower. I don't know if it is mil-spec or if that even matters." The upper attached to the lower w/o using a hammer? Then it's good enough. Why would you think the S&W not "mil-spec"(that's just a "feel good" term anyway)?

April 3, 2017, 08:22 PM	#4
rickyrick Senior Member Join Date: March 15, 2010 Posts: 8,238	If you like it the way it is, keep it that way. I doubt there's anything wrong with your lower.

April 4, 2017, 06:16 PM	#5
Eazyeach Senior Member Join Date: January 14, 2014 Posts: 706	Thanks for the reassurance. I still might slap the BCM on the Colt just because I feel I'm wasting the Colt as a back up. I appreciate your time folks.

April 5, 2017, 08:29 AM	#6
odugrad Senior Member Join Date: March 13, 2013 Location: The East Coast Posts: 477	What parts on the S&W lower are you concerned about failing? If you want, just replace those parts.

April 7, 2017, 06:03 AM	#7
Ibmikey Senior Member Join Date: June 1, 2013 Location: Now relocated to Texas Posts: 2,943	One of my favorite rifles is a Sport lower with different furniture, Aero upper and Faxon LW barrel with 15" Faxon rail. The rifle is light and accurate, I can only guess it has had three or four thousand rounds through it and still knocks over clay pigeons at fifty yards from the shoulder and at 100 supported. There is no way I would morph the Colt, get it out and shoot it! Three hundred rounds through my AR's does not even give one a workout, I try to make as many chunks of brick into powder on my shooting days, dirt clods and soda cans are also good fodder for a hungry AR.