Maybe it is just me? I have a preban bushmaster with a commander barrel and 5.5FH, with collapsable stock. I also own a bushmaster post ban, with a 16" barrel and muzzlebrake (which is loud as hell). My preban I would swear has less kick and/or climb than the post ban? Is there any difference in the rifles that would cause this? Shorter barrel? Also are there alternate recoil springs for AR's? Granted kick is not that much anyway for an AR, just makes me think too much and wanted to know if anyone had an explanation. Thanks, From too much time on my hands!!!

maybe the 5.5 would soak up more recoil than the post break, if your commando upper was heavier, that would matter, but i dout it.

If your preban has the shorter barrel then that could make a difference. It's kind of a trade-off though. Usually a shorter barrel would mean less weight, which would mean more recoil. But the longer barrel usually adds something like 100fps/in. increase. That would theoretically create more force against your shoulder (if you believe in the law of physics). There are probably other things involved here like the response time of the recoil, spring tension, etc. Hmmm...

I'm surprised you can detect the difference.  AR's have such a puny kick to begin with.

Quoted: I'm surprised you can detect the difference.  AR's have such a puny kick to begin with.

Ya your right.
Sounds like we got a pussy in the AR15.com ranks.
c-rock

I doubt I need to justify any of that with a comment, but I will say we are talking about a very slight difference. I just get to shoot a lot and it was something that I noticed. I will trade back and forth trying to figure it out. Basically it has gotten to the point of me willing to sacrifice some accuracy with a short barrel configuration for faster follow up and target accusition. Hell the 11.5" is a lot lighter than a 16". Accuracy still doesn't suffer that much, I can still hit the wild dogs at 200m.

I'm guessing it is a combination of the following factors: carbine buffer vs. standard buffer, 11.5 vs. 16 gas pulse, old style telestock (?) vs. A2 stock, weight, weight distribution, and 11.5 vs. 16 muzzle velocity.  (OK, the last one is unlikely to be noticeable.)

If you could legally do it, I would try swapping uppers to see what happens.