Bulk ammo - seating depth?

Gidday guys - some time ago I bought a quantity of Lapua 223 FMJs. I've had great success pulling the FMJs and replacing these with Hornady 55s (the same weight as the FMJs) despite various internet sources naysaying this sort of practise. These shoot su MOA in two of my rifles which is good enough for most of my purposes.

Anyhoo I'm about out of them so managed to obtain some Belmont 223 stuff. It seems (from reading between the lines on various posts) that different batches of Belmont don't all shoot the same.

Given that the Belmont stuff already has a decent soft point projectile I was wondering if it might be possible to tune them to a particular rifle by experimenting with seating depth - anybody tried this? Any thoughts on a quick way of "lengthening " 400 rounds?

well first thing would be to try them as they are,you might be making work for yourself when none is needed.

Collet bullet puller then reseat for a consistent depth

Yes this would work, only concern is losing a bit of neck tension. I have a tin of Belmont 77hpbt I want to fine tune at some point, shoots great out of Tikka but reckon can get it just wee bit better by adjusting length slightly, ideally it will be slightly shorter. Just never got around to it as don't shoot much 223 these days.

You should be able to fine tune any factory load to your rifle like this in theory, just comes down to time and effort. I have a small RCBS partner press that I can take to range and just clamp to a bench.

Brian and I found that their biggest variation is between Belmont's bullet batches. Sometimes they use Speer 55grn instead of Hornady. We both found that the Hornady shoots best.