I think that more time behind the rifle will offer improvement of both the bore and the shooter.
For my own purposes (factory barrels only), I simply shoot 100rd to fireform the brass, deep clean the bore, then begin load development. After some decades, I'm taking shortcuts with load development and simply setting an arbitrary initial charge by rounding down to the next .5gr below max, and seeing what the target says.
If you have some commercial ammo left over, shoot about ten or so down the pipe to season the bore before starting the actual load development.
Last week, after waiting through over half a year's worth of lockdown, the target told me that two of the three guns were doing well enough with that initial load, and that the third one could use a smidgen of improvement, so I'll be doing bracket loads (just above and just below the initial charge weight) to see which way improvement lies. Doesn't always work, but it sure looked good this time.
I pack too much junk with me, but sometimes it pays. At our club range, the seats are ancient kitchenette chairs and the benches are concrete. The spots where the seats go are so worn, it's a reach up to get onto the bench. So I bring a commercial folding shooting table, and a large-ish folding chair. It makes a big difference. Sometimes a 2" foam seat pad (Boater's Flotation cushion) is all you really need.
The new chassis rifles usually employ an AR style grip, and they vary. I don't shoot chassis rifles (yet), but I have fair number of homebuilt AR's. I've standardized on the
Luth AR Chubby Grip, and I think it does a good job of helping me control my finger/trigger interaction. They also offer a
trigger finger position trainer.
Greg