Home Forums Hunting & Shooting Ask The Gunwriters back pressure from a can

will let you guys settle a discussion here. most people agree you add a suppressor to a barrel that increases back pressure. but a question at hand being discussed is if you had a 6 in suppressor to a 16 inch barrel. will that have more or less back pressure than a 22-in barrel without a suppressor?

I'd venture to say that a 6" can on a 16" barrel will typically have more backpressure than a plain 22" barrel, as you don't see folks needing to run gasbuster charging handles on semi-autos with no cans, regardless of barrel length. Backpressure from my 6+16 setup gets my action pretty filthy on my current AR10 while there are no such issues with my 20" non-suppressed model.

do you think that would change and say a 20 inch standard barrel with a 6-in can compared to a 26 inch barrel?

Are you suppressing a bolt gun or an AR? What caliber are you attempting to quiet? And lastly, which suppressor? Some create much more pressure than others.

we were having just an in general conversation with nothing specific. just going off of a general rule of thumb.

kind of leading up to the next question if a suppressor indeed is equal or more back pressure then it should also provide the same velocity as a longer barrel?

No.

Well if it is a nonspecific discussion then my answer would be maybe or no or possibly yes... depending.

The answer is just as specific as your criteria. It depends, usually not, but sometimes.

The 16”+6” can isn’t going to cause more pressure than a 22” barrel as the gas in the suppressor has somewhere to go/expand between 16” and 22”. Besides, the pressure is actually decreasing as the bullet travels down the bore and the volume increases. So “backpressure” isn’t really a good description of what is going on.

The “backpressure” is really only of concern in gas guns due to bolt unlock/timing issues, the bolt unlocks and extraction starts prior to bullet exit/pressure drop. In a bolt gun, no downside - or else longer barrels would cause issues and they don’t.