I’ve had my PA-10 Gen 3 for almost a year now. I noticed cold bore shots group rather nicely 1 MOA or less using Federal Gold Match 168gr HPBT. The issue, I’m noticing is after normal strings/volumes of fire my groups open up drastically and seems they " walk" on the target. You can have one POI centermass then another at the 1" o clock. It’s baffled me and my friend. Were convinced the PSA ( DC machine) barrel has poor metallurgy as it heats up. We checked the barrel nut and it appears tight. ( we can recheck) I don’t see these same issues with a mid tier barrel like a Criterion Core, which is consistent. I’ve read a few stories of PA-10’s having the same issue and people swap the barrels out. Can anyone else confirm our findings? I know ALL barrels do this to some degree, but it shouldn’t be greater 3+ inches of MOA/POI. It’s got the whole " UFO effect" going on after heating up. Where the groups are somewhat unpredictable.
I know the PSA barrel is 416R stainless steel. But my question is the quality of the steel used.
Have you tried different ammo? Are you using a suppressor? Is your optic a quality optic in a quality mount?
I ask all this because there are A LOT of variables. I had a friend with a really nice set up that shot extremely accurate until he used is suppressor. Just didnt group well at all. Ive also seen some barrels like a specific ammo.
No supressor. Goodpoints, the more data the better. The optic is a Vortex 5x25x50 mounted in a Warne ASKEL 20 MOA mount. I torqued everything down with a wheeler FAT wrench. Then marked the bolts with a white pen.
As far as loads go. I’ve tried 150,168’s even some hand loads and the effect is the same. Perhaps, I should try doing a " ladder load" and see what the barrel likes.
Ah - @GuitarGuy brings up something I hadn’t thought of.
Is the muzzle device seated completely against the tip of the barrel, or is there a gap between the device and crown? What does the muzzle crown look like under the device? Are there any [carbon] deposits in the gap (if there is one)?
I’ll have to use my barrel wrench and remove it and take a look. I suppose, I could also use my bore scope and see the general condition of the bore for further analysis.
If it’s the A2, it probably doesn’t seat against the muzzle crown - you can likely see the crown without removing it, using a bright torch. (unloaded, open bolt, etc. - goes without saying, but I will anyway)
My Gen 3 PA10 does similar but right off the bat it scatters rounds in a 3 moa group at 100 yards no matter the ammo from M80 ball, hunting to match and has never shot a decent group.
Maybe consider lapping the upper receiver face flat, and Loctiting the barrel in place ?
I have had great success doing the above.
I suggest this because you mentioned “after it warms up.”