Best Seating Die for RMR 124 Gr Round Nose?

[David Kemp]

I recently bought a Redding Competition Seating Die for my 9mm RMR Round Nose bullets, looking to get the best uniformity in COAL and bullet alignment with my RCBS ProChucker7 progressive. My Staccato XL seems to be happiest when I seat to 1.127″ COAL. But the results are anything but uniform with this die. I checked my most recent batch and found COALs from 1.133″ down to 1.123″. I’ve eliminated every variable that could influence overall length. It’s gotta be the fancy die. Can anyone recommend a die that can give me better results?

[brett1955]

+- .005 is acceptable and sometimes is as good as it will get for any bullet. The ogive of the bullet and the amount of pressure it takes to seat the bullet will change bullet to bullet. I load about 35-40 different bullets and alot of them will fluctuate that much and more. I have found that the RMR MW is the most consistent with COL’s and it will be off +- .002. I round off my COL measurement to a .005 ( 1.125 or 1.130 ect.) there will be no change in pressure or accuracy or function, unless you are already to long or short. Set your calipers to .005 and look at it and see the difference. good-luck Brett

[David Kemp]

brett1955, I’m glad you mentioned the Matchwinner. Until 6 months ago, that was my standard bullet, and I got the same great +/- tolerances you mention. I’ve settled on the RMR round nose because it feeds a smidge more reliably in the Staccato. If the bullet punch profile were an exact match for either bullet, there’s no reason the seating variances would be any different. But without machining an exact copy of the bullet, no punch will be perfect. Thanks for your insight. I was expecting the round nose seating to match the MW variances.

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