At what point does a barrel lose accuracy during a range day? Went out yesterday as I've been trying to dial in my 18" stainless steel wylde barrel. Had some challenges with the scope mount coming loose before so I tightened everything up.

First 3 shot group at 50 yards to sight it in was 4" left but one ragged hole with Hornady black. 20 rounds later by group spread was around 6 moa. Scope? Mount? Barrel? Shooting ability leave much to be desired? It's getting a bit frustrating...

Depends on the gun and barrel and how much you shoot. If you only shot 4 rounds and then 20 minutes later another for that dropped to 6moa then I'd say you got a problem.

If you shot continuously with a feather weight barrel for 20 minutes then I would say maybe not.

A lot of people only shoot on a cold bore. 3 shots maybe, wait 45 mintue then do 3 more. Just to make sure they are zeroed on a cold bore for hunting.

If under 10rpm sustained, ought to be a few hundred rounds later if/when fouling builds up enough to affect it.

Something sounds loose or misaligned.

Sounds like your stuff is coming loose....or your position is getting bad as you shoot...

Agreed, I think something is loose.  I've been sighting in before, then all of a sudden had my groups severely open up.  Turns out my front scope ring loosened up on the scope base...

Thanks guys. I'll make sure to take the torque wrench to the range next time to make sure everything is tightened up and if groups open up, check again. I'm also thinking my position is an issue and after the first open group, frustration (thinking it's the gear) sets in and it's downhill from there.