338 Lapua Redding Body Die Issues

[Chargerguy]

I've been loading the 338 Lapua for a TRG without issue. But today I tried doing the same for an AX and ran into some issues I haven't experienced before. Using the same redding body die that'll bump the brass for the TRG 0.002" no problem (measured using a Wilson micrometer case gage) and will allow the bolt to close with zero resistance I'm actually getting a harder bolt close with the AX after bumping.

I measured 5 once fired and AMP annealed Lapua cases with the wilson case gage and they varied about 0.001". I numbered the cases with a sharpie and grabbed the first one and tested it in the rifle with a stripped bolt (no firing mechanism or ejector). Very light resistance on closing. Started bumping back the case with the redding body die and with a 0.003" bump the bolt close was significantly stiffer. Got to 0.006" bump and same thing. Pulled out a second Redding body die I had and tried another case with that one. Same results.

I had some once fired TRG brass (much older Lapua lot). So I sized one with a 0.002" bump and the bolt on the TRG closed with zero resistance. And it had resistance before the bump. I did notice more force was required to run the case into the body die for the TRG brass. Bigger chamber most likely.

So then I took another once fired case from the AX, measured the OAL, it was 2.7195" and then measured the case datum at +0.0085" from zero on the Wilson case gage micrometer. I ran the case through my Lee collet die first (I like to collet then bump). The die was set up to touch the shell holder plus 1 turn. This resulted in a lot of travel of the collet up into the die and pretty much no resistance right up until the end of the press stroke, so pretty far from being screwed in too much. The same case now went from 2.7195" to 2.7205" OAL and the shoulder went from +0.0085" to +0.0047" (I am estimating the 1/10 thou measurement). I then bumped this case about 0.003" to +0.0015" on the wilson micrometer. Stiff close on the bolt still.

I think I just need a tighter body die and neither Redding die is sizing the body enough. Any recommendations on die/brand? Maybe a FL bushing die for future versatility. Or am I missing something here?

I should note, I did test some of the remaining unfired Lapua brass from that lot in the AX and the bolt closes with zero resistance.

 

[spife7980]

You think you need a die because of body diameters… well measure the body diameters too and find out.

 

[Chargerguy]

Thanks, I needed that.

Compared new, fired, and "bumped" with the micrometer. Everything shrank or stayed the same diameter wise, nothing grew. The Wilson gage was new to me, first time I used it, so I put that away and pulled out the Hornady headspace comparator. The body die was causing the brass to flow and actually reduce my headspace, but changing the geometry in a way that made it look like I got significant bump with the Wilson. So when I thought I was already at 0.006" bump, the hornady comparator said I actually gained 0.0005" and wasn't getting any bump yet. Screwed it in some more. Getting an actual 0.002" now on the comparator. Checked in the chamber, no resistance on the bolt, added some 0.003" scotch tape to the base of the case, hard stop on the bolt. Checked in the Wilson gage, according to it I'm bumping 0.008".