More info. Here's one for the suppressor experts. Update!

[Bear44]

I had an interesting thing happen today at the range. I was getting a zero on a new to me Rem M-7 in 300blk. When shooting subsonic ammo with a suppressor I discovered that the first round with fresh air in the suppressor is wildly erratic and inaccurate. I'm talking group sizes at 100 yards measured in feet, rather than inches. However, once the suppressor has had the air burned off by the first round and it is filled with gas, the accuracy becomes consistently around 1.25 MOA. I went back and forth with these two conditions about a dozen times and it was happening every time. It also did not happen with supersonic ammo.

Anyone ever seen or heard of this and, more importantly, is there a solution?

 

[Glockspeed31]

What subsonic and supersonic rounds are you shooting? What suppressor are you using?

 

[chrislibby88]

Are you shooting direct thread or QD mount?

 

[Bear44]

What subsonic and supersonic rounds are you shooting? What suppressor are you using?

Gorilla 205gr expanding.
Nosler 125gr Ballistic Tip.
AAC Cyclone direct thread.

 

[Bear44]

Are you shooting direct thread or QD mount?

Direct thread.

 

[chrislibby88]

Found a write up on your same issue. The author said one of his baffles didn’t quite have enough clearance and was causing some interference with the round. Guess once the suppressor heats up and expands it goes away.

Here s a link to then article.
https://langhallsskytte.com/2014/01/25/problems-with-suppressors/

 

[Burdy]

I had an interesting thing happen today at the range. I was getting a zero on a new to me Rem M-7 in 300blk. When shooting subsonic ammo with a suppressor I discovered that the first round with fresh air in the suppressor is wildly erratic and inaccurate. I'm talking group sizes at 100 yards measured in feet, rather than inches. However, once the suppressor has had the air burned off by the first round and it is filled with gas, the accuracy becomes consistently around 1.25 MOA. I went back and forth with these two conditions about a dozen times and it was happening every time. It also did not happen with supersonic ammo.

Anyone ever seen or heard of this and, more importantly, is there a solution?

You are getting a baffle strike sir.

 

[chrislibby88]

Is your suppressor new or old and is it serviable?

 

[batoncolle]

You may have a baffle strike, although you should be seeing similar issues with the supersonic ammo as well. Also some cans will have a cold bore POI shift, although not as drastic as you're talking about.

Shine a light down the can and see if you see any damage. Also what was your rate of fire?

 

[Bear44]

I'm not getting a baffle strike. No sound and it reacts the same hot or cold. I could shoot when there was gas in the can and it was accurate, let the gas escape by holding the rifle muzzle up with the bolt open for about 30 seconds and the next round was erratic. I went back and forth in rapid succession several times. Also, no accuracy issues under any circumstances with supersonic ammo.

The erratic rounds are not keyholing at all.