Can Suppressors cause Minor Over-Pressure in a Borderline Situation?

General Discussion Reloading
1

Caliber - 308.
Loads -
180 grain Barnes TSX, 4198 powder, loads 36.5 & 37.0 grains.
170 grain Lapua Full Metal Jacket, 4198 powder, loads 36.5 & 37.0 grains.
180 grain Barnes TTSX, IMR 8208, 40 grains

A few months ago I got an Over-pressure with these same loads, shooting with a Suppressor.

I didn’t track the brasses. -1- of them was Over-pressure.

Then I wanted to load more, especially with the IMR 4198 - but I didn’t want to load bullets that would go over-pressure.

So today I shot 1 or 2 each of the prospective loads - WITHOUT the Suppressor.

No Over-pressure !

So I’m thinking - everything is OK, my loads are good.

Or MAYBE, the Suppressor was a factor in the Over-pressure.

I didn’t use the Suppressor today because I’m tired of cleaning it.

Can a Clean Suppressor push a situation that is safe pressure-wise, into one that is mildly over-pressure ?

Suppressor is an OSS Helix.

2

Suppressors create back pressure. They allow the gas to expand without exiting behind the bullet.

3

I don’t know the science behind how suppressors work. But I do know that most factory ammo is pretty hot so I don’t think a suppressor would cause an unsafe condition.

4

um yes.

5

Yessss. both my 5.56 and .308 cans have resulted in major overpressure issues in my rifles. Shorter barrels don’t help either.

Add adjustable gas blocks and H3 buffers

6

Do you mean overpressure that causes pressure marks on brass ?

or the way that the gas blows back in the face of the person shooting ?

7

So if suppressors cause pressure issues, along with the added weight, expense, and the permission slips required to own them, just what is the attraction? A few less Db?

8

Yes. With subsonic ammo they are stupid quiet.

9

No. Over pressure as in feeding and extraction issues.

10

Suppressors CAN cause overpressure issues, but most are designed not to. Now my problem comes from reduced barrel length. My suppressed rifles had no issues when they were full length. For example, my AR15 got wonky when i shortened it from 16” to 10.5”. Even going back up to 12.5” has required an H3 buffer and an adjustable gas block.

11

I actually Read the Instructions !

for my OSS Helix, it says no cleaning is necessary.

The person I know that has the most suppressors, at least a dozen, is super religious about cleaning them.

That’s basically his Evening Activity. His wife watches TV in the family room, while he cleans his suppressors and other firearms stuff.

So who do I listen to ?

One thing about suppressors is, the film of oil and smoke that accumulates between the bolt and the chamber is like Superglue.

if you blow out a primer, and it separates, the 2 pieces often get stuck in the next-to-the-chamber area, where they interfere with the bolt seating.

As far as my own Standard Operating Procedure, I have to learn to “pay the tax” when I use the suppressor. i.e. clean it. Or simply shoot un-suppressed, until I have time to clean the suppressor.

12

I have never cleaned my suppressors. I think i’ll give it a go and see if it changes anything

13

This is slightly off topic but it relates to suppressors, I’m ISO a can that is 1.25 in diameter for the purpose of pin and weld to a 10.3 barrel on a 16 inch hand guard so most of the can is inside the foregrip. Kinetic Suppressors out of AZ had a product named the Joker 556, however, they are no longer making that product. Any suggestions??? I’m quickly running out of options and may just re-think the build.

14

Dont pin and weld a suppressor.

15

Are you saying that because because a suppressor needs to be cleaned regularly?

16

For clarity, I was going to pin and weld to avoid another tax stamp ( SBR and a can ).

17

Im saying that because a) you void the warranty on your can and b) if you ever get a second gun of the same caliber you will regret a pin and weld.

18

Gotcha…back to my original question…any leads on a can with an O.D. of 1.25?

19

Im not aware of any that small.

20

Thanks. I certainly did not intend to sound argumentative but after re-reading my response I was able to see how it could be taken that way. Y’all have a wealth of knowledge and experience and are willing to share it with those of with less knowledge and experience. Thanks to each of you that give heartfelt, honest and practical advice to those of us with many questions. THANKS