To really understand the difference a suppressor makes on a gas gun, it helps to check full auto cyclic rates on an electronic timer - even if you do not plan to shoot full auto.
Cyclic rate - suppressed - is typically much, much higher than unsuppressed, 40% or more greater with some suppressor brands. This increase in RPM is a function of increased dwell time and more back pressure. But, just one thing is happening faster, the bolt carrier group doing its thing moving rearward. This is a potential reliability issue, especially as the gun gets dirty - which of course it will, and much faster suppressed.
There are band aids for this problem that will help - but not eliminate it.
The Larue PST and Noveske Switchblock give the shooter the option of a reduced gas setting - but will that be exactly right for your particular suppressor??? Noveske's suppressed Switchblock settings were derived using AAC suppressors. Will that be enough reduction for a Thunderbeast, or too much for a Surefire? Larue advertises their PST suppressed settings were developed using Surefire suppressors. How will the PST work with other suppressors?
A gas port size selected to run with your suppressor at an appropriate cyclic rate is one complicated solution, and that's what I did with a recent batch of Noveske 10.5" SS barrels. I'm not the first to do this. It's a lot easier to make a gas port bigger than smaller, so starting small is the way to go. But, it can be a pain to fixture up and enlarge a gas port. Once you're close to where you want to be, you can fine tune with different buffer weights. I've found the Vltor A5 recoil system to be very helpful in this regard. My own "suppressed only" 10.5" with custom Noveske SS barrel:
This combo initially ran at an unbelievably low 615 RPM (with ASYM 55 grain FMJ practice ammo) with a Vltor A2 buffer. I'm sure it would not have been reliable that slow when dirty. Switching to a Vltor A1 buffer bumped the cyclic rate up to 720 RPM, exactly where I want to be. The gun runs very smoothly, with amazingly low recoil. I won't even tell you how this thing will shoot with a scope and match ammo, because you wouldn't believe me, and that really doesn't matter in a practical sense for a CQB weapon. What the accuracy does indicate is that things are functioning well. This upper seems to carbon up more slowly than my other 10.5" with a normal gas port when run suppressed. But - They all get dirty suppressed - from pressure trapped in the suppressor running back through the barrel as the BCG cycles more than from being a gas driven design. Piston guns fired suppressed do much the same.
A "suppressed only" rig is not for everyone. There are numerous proven methods for helping cope with excessive gas pressures, but none eliminate the problem quite like having the right size gas port.
Enter the Syrac gas block, a positive click adjustable device that will potentially provide the best of both worlds. You'll be able to make precise, repeatable adjustments with it just like you do with the Zero-Stop on your scope's elevation turret.
All future SS barrels we get from Noveske Rifleworks will have a Syrac gas block.
