Quote Originally Posted by 1168 View Post
It makes no sense that either type would behave differently when added to a rifle buffer and tube, carbine buffer and tube, or A5 buffer and tube. All have the exact same travel, thus the exact same dimensional window for a 9mm spacer.
I believe they stated that because the standard carbine tube is 3/4” shorter than the A5/rifle tube, the spacer will eliminate the use of the bolt catch with said carbine system.

Appreciate your time explaining this, I’ve built a few 556 ARs, but this is new territory.

After sleeping on it, I will probably go with the A5 system I’ve got in the parts bin. Makes sense to me because I will be running shorter barrels/gas systems on the pistol lower; I feel like the A5 would tame any higher felt recoil from the shorter uppers.