Using RCBS seater/crimp die in 2 stages

[Laggy]

I’ve loaded tons of 45 auto, 308, 270 and some 300 WM as a reference.

So I’m loading 44 mag and 10mm for the first time. Rockchucker single stage. Carbide dies. 44’s going off without a hitch.

10mm’s in loading RMR 180 FMJ-FP’s. I was getting some buckling on some of the last rounds out of 100. My expanding/flaring is very conservative (ie. just barely belled). Like so much so that I have to hold the bullet above the case on some rounds. The bullets all drop in the barrel with zero interference.

I was gonna try a little deeper with the expanding plug. But I wanted to try seating all the bullets, then backing the seater out and doing the crimp in a separate step. I have no idea of the quality of the RCBS die’s taper crimp ability vs Lee FCD or Redding dedicated dies. I figured that a separate crimp process is a 4th step anyway.

P.S. The brass is inconsistent. Some of it is as much as .010+ shorter than trim-to length. Some of the cases have a slant when looking at them side-on. I’d trim them, but again, those cases are already too short.

I’ll get all Starline here eventually. It’s range brass. Some good ones, but there’s many pieces of hot trash in there that I’m gonna have to toss.

Opinions? Education?

 

[Charlie98]

The only way to reliably crimp is to square those case mouths up, let alone trim to the same length. Although I'm not a big fan of the FCD, this might be a good place to try it.

In my experience, the dedicated taper crimp dies are a little more progressive on the crimp... that is to say, it seems like the actual taper to the crimp is a little less aggressive. I have RCBS .45ACP dies, I never even knew the seat/crimp die was a taper crimp, I thought it was a roll crimp all these years.

 

[PWC]

I've always used RCBS seat/crimp dies in 2 steps. As Charlie 98 said, untrimmed brass will give inconsistent crimp. If it's for non-competative shooting you probably won't see a great difference.

 

[Laggy]

Problem solved. No more buckling.

1) I ended up setting the expander plug just a touch deeper. Originally, the “belling” was .010 flare, now it’s about .020. RCBS manual says .030 or less. Bullets snap-in a little more positive.

2) Seating first. Backed out the crimp part of the seater die.

P.S. 180’s with 13.0, 13.3 and 13.5 of Accurate #9’s we’re boomers! Man that’s a crazy powder. I’m gonna get some Ramshot Silhouette or Accurate #5. It will be easier to send a few hundred down range. I had a pound of Vihtavouri N340 that I’m gonna use for these 10mm’s in the meantime.

 

[film495]

I've used RCBS dies, and to avoid buckled cases, seat them all, then go back, and by hand touch the crimp to each case manually by turning it until it touches, and then turn and crimp to a predetermined amount. It is more time consuming, but even on trimmed brass, the variation can be surprising.

I don't know if I'd do this again, but I was trying to figure out a failing plunk test, and - separating the steps gave me a better clue as to where the cases were deforming, could not see it by eye.

 

[Laggy]

So admittedly, all the rounds drop all the way in barrel with zero interference.

I think separating the steps is the easiest. Belling enough is more important than I thought. I thought I was “cheating the system” with .010 of belling. But .010 is not enough. And .010 of flare on a .990 case is .005 on a .980 case. I was also getting fine slivers of jacketing previously, now there’s none. I was worried about working more of the brass, but I think my concern is not justified.

Learning.