This is in reference to 10.5" barrel and 11.5" barrel with carbine length gasblock and 14.5" and 16" with midlength gasblock.
In regards to 14.5 middies I always hear it is softer shooting, has less pressure, easier on parts compared to 16" middie. Therefore 14.5 middy is “better”, less dwell time.
When in hear about 10.5 vs 11.5 I hear the 10.5 is harder on parts. 11.5 is better because more dwell time which is better.
Why is less dwell time better for 14.5 good and more dwell time is better with shorter barrel?
In this scenario the 10.5 car = 14.5 middy and 11.5 car = 16.0 middy
I own a 10.5 MRP 16" BCM MIDDY both are very smooth and I have only compared it to rra 11.5 and 14.5" bushy with carbine gas length. In both cases my LMT and BCM shot “smoother” which is not an apples to apples comparison.
ETA: Guess my question is, why is less barrel in front for GB good for 14.5 (vs 16) but not 10.5 (vs 11.5)
The comparison between the 14.5 middie and 14.5/16 CAR is the most referenced “softer, smoother, easier”. I can’t recall anyone making an apples to apples comparison between a 16" and a 14.5" middie and proclaiming the 14.5" to be significantly “better”. I absolutely could be wrong since I am only on sporadically due to my current schedule. Regardless, the 14.5 middies that are often talked about have the operating system balanced to near perfection, which make a hell of a lot of difference.
A 16" carbine length gas system is theoretically more destructive to the operating system than a 14.5" carbine length system if both gas ports and operating systems are identical. In actual practice, knowledgable shooters will install different buffers and BCGs to get the gun to work like they want.
When it comes to SBRs, the 10.5 are harder because they have to have larger gas ports to work, which turns into sharper recoil if everything is left the same. One again, in actual practice the shooter will be able to tune the system to ensure reliability and shootability.
In my experience, 12.5 guns are easier to get running with and without a suppressor than anything shorter. 14.5" car gas guns feel slightly more bouncy than 16" middies, but better than 16" CARs. I cannot compare 16" middies to 14.5" middes.
from your example and questions, I think the greater dwell time on the 11.5 is better than the 10.5 because of operational/reliability issues, not softness of shooting. SBRs really need to have larger gasports and work in a smaller threshold of operability.
a 14.5 mid is “better” because it shoots softer and doesn’t sacrifice reliability. even with a quality upper that has the correct size gas port, an H or H2 buffer is optimal. if you’re under-gassed with a 14.5 middy, it’s easy to fix with a lighter buffer.
I think the context of “better” is the cause of your confusion…
So if reliability was taken out the the equation a 10.5 “IN THEORY” would be superior as far a recoil impulse. Of course we are excluding the velocity benefits.
The only reviews online I’ve seen so far had some sort of muzzle break/compensator on rifle. They were comparing them against another rifle with a standard A2 flashhider.
Has anyone done an apples-to-apples comparison of a BCM 16" middy vs. a BCM 14.5" middy, both with the same muzzle device, which compared shooting characteristics as well as reliability?
If you had two 5.56 bolt guns, the 10.5" would have the least amount of felt recoil.
However, you can’t really take reliability out of the equation when comparing ARs since many of the issues will affect reliability. As it is, the 10.5s have a larger gas port than the 12.5s, which increases felt recoil and bounce.