I'm running a SF socom 308 mini on either an 18" LMT MWS or a KAC SR25 ECC, both in 308. For some reason, I've been experiencing some challenges while shooting suppressed that I can't figure out.

On either rifle, my first 20-25 rounds are spot on. I'm able to hold 1moa pretty easily, zero is consistent. However, as the day progresses and the can/ rifle gets hotter I start to see accuracy issues. I start to get 1-2 unexplained flyers from a 5 shot group, and POI starts to wander a bit.

What ever is going on is extremely frustrating. I'm currently not running a can cover, but the mirage itself isn't the issue. I plan to get a cover just to completely eliminate that variable, but I'm looking for experience from others.

Those of you shooting your precision semi auto suppressed is your rig always 100% consistent? Do experience accuracy degradation as the can heats up? Worst case I could just pull the can and shoot but that's kind of giving in and I'd prefer to figure out my issue.

Thanks

The muzzle, being the last place the bullet exits, ends up undergoing some pretty extreme temperature shifts with a brake attach or direct-thread attachment.

As the steel heats up, any opportunity for residual stress to manifest in dimensional shifts often happens.

This is true when:

* Barrel steel quality is iffy near the muzzle (not saying this is your problem)

* Threads are not concentric to the bore

* Threads are not square to the bore

* Thread shoulder is not square to the bore

* Suppressor body is not concentric to the bore

* Baffle arrangement is not concentric to the suppressor body and bore

* Baffle bores are not concentric

* Integrity of the baffle construction has variance in manufacturing processes

* Lock-up of the can to the brake shifts with heating

I could go on.  The engineering challenges of getting concentricity over time with heated strings of fire between 2 or more alloys are no trivial.

It's one of the reasons ThunderBeast suppressors are one of the most popular in PRS as well.

I think all of these variables are why I find it so frustrating. Something is clearly going on when things start to heat up. I'm reasonably confident the suppressor is the culprit as I've tried the same suppressor on 2 separate rifles with 2 different scopes.

Symptoms are almost identical between the 2. The first rounds are spot on, then as the can gets hot enough you can't really touch it things start to get goofy...

There are precious few suppressor companies that have concentric cores to the bore and OD of the tube due to the construction methods commonly used.

Which ones are they?

After that much shooting you will get mirage off the can even if you think you're not. I had the same issue with my obr when I first started shooting suppressed. 

I took my brand new Larue PredatOBR 7.62 out today with a Nightforce 2.5-10x42.  I had a Gemtec on it, I experienced the same problem...  I got it zero'ed (or at least I thought)  then my shots were spreading out as much as 4-5 inches at 100yds.  I was getting really frustrated for about 1hr.

I took the suppressor off.  Put on the Larue brand muzzle brake and immediately started making holes touch no mater how fast I shot.  Then started changing distances between 100-600yds.  Was shooting bulls eyes up to 400yds on first shots, 600 they opened up a little due to wind.

I really like shooting suppressed but now... I think I will stick to busting ear drums.