AR15 Grendel and 7.62X39 comparison

[Texas]

I just completed a 7.62X39 with a 16" barrel so that I would have something that shoots the same round with the ergonomics of my other ARs and I do not need to rely on an AK variant. While sighting it in today, I was also shooting my Grendel. It may be my imagination but there seemed to be a marked difference in recoil.
I shot factory 123 gr. Hornady AMAX in the Grendel and 123 gr Winchester FMJ in the 7.62X39. Both rifles are the same approximate weight, but the Grendel seemed to have significantly less felt recoil.

Has anyone else noticed a difference?

[GSPHunter]

Hi TX....One thing I've noticed is that bolt speed and buffer mass can change the felt recoil. With the bolt slowed down, It seems to push more than slap( and thus I "feel" it more) . Just my limited experience, but it could be that your Grendel has a bit more gas flowing compared to the 7.62x39.

[rabiddawg]

Texas, I too have noticed what you are talking about. My grendels are much more pleasant to shoot than my .223.

[LRRPF52]

Gas system length is one of the big contributors to perceived or felt recoil in the AR15.

CLGS usually are pretty brisk or violent.

MLGS and RLGS are much smoother, RLGS especially.

What barrel length and gas system length on your Grendel?