I was in our store front the other day and guy was trying to buy a heavier buffer for his .308.  He was having trouble with the bolt cycling when he was running his suppressor.  When his suppressor was removed it cycled flawlessly, but when he put it on it didn’t have enough pressure to cycle the bolt to eject the casing and load another round into the chamber.  

This is a common thing that we see is having cycling issues.  It is common with AR pistols having too much gas pressure.  When you have a round that is typically used with a carbine or mid-length gas system when you drop that to a 7.5” pistol gas length to have was too much pressure.  Additionally when you are running both subsonic and supersonic ammo of the same caliber it can lack the pressure to cycle the bolt.  Much like the guy who was in the shop running suppressed and unsuppressed.  Also we see this with the larger bore rounds like .450 Bushmaster, .458 SOCOM, and 12.7x42 (.50 Beowulf) where they have too much pressure with the gas system.  

While this isn’t always the case, and swapping buffers can be a simple and effective solution to this problem, running an adjustable gas block is also a great solution.  This way you can dial in specifically to both your weapon and even make micro adjustments to account for different types and weights of ammunition.