Confused about 10.5 v 11.5 and 14.5 v 16

[ryu_sekai]

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)

 

[SSSamurai]

Re: Confused about 10.5 v 11.5 and 14.5 v 16

All of that depends on the gas port sizing. It is true that 10.5s are the hardest on the system because you're tapping the gas earlier, and with the short dwell time you have to tap more of it to guarantee function. 11.5s allow you to use a smaller port size since you have more dwell time. This slows the wear and tear down. If the manufacturer uses the same port for an 11.5 it will actually wear faster, all other things being equal. The same logic applies to the longer barrels. If you use the same port size, a 16 will dump more gas than a 14.5, causing more wear and probably more felt recoil. However, a 16 with a smaller port should give you less wear and less recoil by spreading the pressure over a longer dwell time. This is excluding all the other factors like buffer weight, buffer spring tension, carrier ports.... Does that make sense?
Jason

 

[ryu_sekai]

Re: Confused about 10.5 v 11.5 and 14.5 v 16

I see, makes more sense now