Several things jump out at me.
You need to size the bullets if for no other reason than uniformity. I use a Lee .401” push through sizer.
Secondly, you need to crimp, to eliminate the flare from expanding the case neck to allow seating of the bullet without shaving the bullet. You are flaring, aren’t you? !!!
The SWC bullet needs to be seated slightly deeper due to possible impingement on the throat of the chamber.
A “gauge” is not YOUR BARREL. Many barrels are cut undersized (and oversized, ie: Glocks), so you may need to do something different.
I recently replaced my 24yr old Glock barrel in my M22 with a CHEAP Bear Creek Arsenal barrel.
I’M ASTONISHED at the improvement in accuracy! I’m getting sub 2” groups at 25yds where I previously got 5-6” groups with factory barrel. (Match grade jacketed ammo...).
New barrel cost me $43.00 delivered. Drop in fit, though it’s nice and snug...