I put a new Ballistic Advantage 18" (rifle-length gas tube) on my Precision AR.
I took her out to the range to try some different factory loads to see what it likes (second time out with the new barrel).
Admittedly, I was in a hurry. I tried to not let that affect each shot-break, but it definitely sped up the rounds per minute that went through the barrel.
I went through eight different loads.
At first, the rounds grouped high, but otherwise in a pattern as you might expect.
As I worked through the different loads, the rounds started to string vertically.
I went back and shot another group of Fed. Gold Medal Match and it also strung out vertically, whereas it didn't the first time. I took my time, and put five more rounds through the tube waiting between each shot (I wasn't really 'waiting' between shots before more than just re-acquiring the target, breathing, and breaking the trigger).
This is what I got:
Other than what looks like a flyer, this group looks like the first 69gr FGMM group (which I'm happy about).
How much time do you wait between each shot?
Do you agree that the vertical stringing is the result of the barrel heating up from rapid shooting? Or do you think it was just shooter's error and I'm blaming it on barrel temperature?