[AGG]

Alright guys--- I need your assistance on a Z-Apocolypse build!!! :wink:
I have a pre-1994 Rock River Arms lower (presume small hole upper- front pivot pin lug/rear takedown lug).
My question is this--- will an MR556 complete upper attach perfectly to the RRA lower? :biggrin:

Tony

 

[pb_removed]

Alright guys--- I need your assistance on a Z-Apocolypse build!!! :wink:
I have a pre-1994 Rock River Arms lower (presume small hole upper- front pivot pin lug/rear takedown lug).
My question is this--- will an MR556 complete upper attach perfectly to the RRA lower? :biggrin:

Tony

I was not aware RR had a "large" front pin as with the old Colts but bushmaster makes an adapter none the less. You may have issue with the notoriously tight fit between the upper and lower that many RR's have. I could not use one of my 416 uppers on a Noveske for this reason.

 

[AGG]

Thank you very much--- I was thinking along the same lines!!! :wink:
Would headspacing be an issue if it is a factory MR556 complete upper?

Tony

 

[LCSO264]

Since you brought it up, which pre '86 lowers do 416 "generally" work on? I think I've seen posts regarding pre '86 Colts....

 

[guncrazy17]

Thank you very much--- I was thinking along the same lines!!! :wink:
Would headspacing be an issue if it is a factory MR556 complete upper?

Tony

Headspace does not even come into play with a non HK lower. My MR556 upper is mated to a Stag lower and works perfectly fine and I can use whatever mags I want to.