Thread: Need help understanding shoulder bump

I've asked about this previously but never really got my head around it. Just now I've found my .338 Lapua brass is tight to chamber after been fired and neck-sized twice, I am using Redding deluxe dies, and just measuring COAL rather than measuring from the ogive as I just anted the loaded rounds to fit in the magazine (rifle is a Savage) accuracy has been excellent but with the cost of Lapua brass I want to be mindful of brass longevity.

So, am I correct in understanding I need to get a shoulder collar to fit the shoulder angle (and maybe a better set of calipers) to measure headspace from my fire-formed cases, then play around with my FL sizing die to bump the shoulder 2 thou or so, or maybe get a set of Redding competition shell holders in 2 thou increments to do it? If I do it by just unscrewing the FL die, will it mean the necks will not be sized fully? Also, I see that standalone shoulder bump dies don't seem to be available for the .338, so could I just get an engineer to bore out the neck part of the FL size so it leaves the neck alone, and neck size with the neck size die as a separate step? Will doing the above still work the body of the case to any degree worth worrying about?

Cheers for any advice, Tom