[35NCO]

JJ, I would think 5.56 pressure would be brutal on the 9k. SBR pressure far worse. The stellite might handle it, but would question the hoop stress on the tube. Please post what they say.

For short 5.56,

Centerfire suppressors tend to have more volume and less baffles to accomplish the task. Going shorter decreases efficency in overall Db, while increasing work/stress per baffle and chamber. Many of the the high performing centerfire suppressors have less baffles per volume but different geometry to diffuse and redirect the high pressure. This pressure delay created with increase or decrease in dwell as a function of volume and cartridge, will also effect your back pressure.

You need to be below 140 to be hearing safe. I think even 138 is still pretty loud. But, just because it is brief impulse noise does not mean that it is not damaging in long term duration endurance. Perception of tone matters too in our physiological response IMO.

Short suppressors will remove some bark of the muzzle, but generate more heat, more sound, and more backpressure depending on the design, comparativly to a full size. I would recommend some kind of adjustable gas block, like micro moa or the alike to tune a setup like that. A longer barrel would be better than a Sbr with a short can if you want comfort and weapon reliability in the long term. Otherwise you are retuning the port size and gas dwell to get what you want. Your ammo of choice will decide your setup for proper tuning.

Quick detach centerfire rifle suppressors are generally louder because you are taking away more vessel volume with the detach assembly. They also add more weight. So in many ways for db reduction, a thread mount is better. Reflex is another option, but more first round pop.