Concentricity Problem With .223 Remington Redding Competition Bullet Seating Die

I was getting as much as .005 thou runout with the above die and called Redding Customer Service for help. They suggested as very low drag seating stem for the 53 grain flat base Sierra Match Kings that I was using but it didn't help so I filled the cavity in same with glass bedding and fit the bullet to it so that I got a perfect fit between the stem and bullet. This helped some but didn't eliminate the problem as concentricity still varied between .001 and .005, then I remembered something that I read on the web that someone had the same problem with a Wilson Seater. He felt that the case wasn't going far enough into the die which allowed it to "wobble" when seating the bullet giving differences in runout. In desperation I removed the sliding portion of my die and seated a case then with the shellholder held firmly against it and slid a feeler gauge between the base of the case and the bottom of the shellholder. I was surprised to find that there was .005 clearance possibly because the top of the shellholder was thicker than spec. I then chucked the sliding case holder portion of the Redding die in my lathe and removed .006 thou from the bottom and reassembled it. Doing this made the shoulder of my brass touch the inside shoulder of the die gently forcing it into alignment and eliminating any wobble. After seating a few bullets I was pleased to find that concentricity was .0015 - .001 thou virtually the same as the runout in the brass before seating.

You found one of the reasons I don't like Redding dies.

Just curious if you're FL or neck sizing your brass? You could be pushing the shoulder back to far, which would cause the case shoulder not to contact the sleeve shoulder. If you're FL sizing or neck sizing and bumping the shoulder back, you only need to set the shoulder back .002-.003 for bolt guns and .003-.005 for semi-autos to ensure good feeding.

I'm both full length and neck sizing as well as using Winchester and Lapua brass. The problem persisted with both. The problem may have been originally caused by a shellholder that was too thick at the top but that's another story. I should note that my full length Lee sizer only give me a runout of no more than .0015 with Winchester brass but twice that with Lapua probably because of the thicker necks, so I usually F.L. size without the expander with these and expand separately using a Sinclair expander for their neck turning tool.

Check your base to Datum again after neck sizing. Neck sizing seperately will change the Datum, draws in the angle, so include that in the end results. Sinclair expander will work, check to make sure it is true and centered in the body for it, some are not, lube it, Imperial. Case neck's square and inside chamfer square. Graphite powder the neck's. Straight bullet placement before seating. Check shell holders for square, some are not.

Just some tips, Brad

Thanks for the tips Brad. Will do.

Does anyone find that the brand of press has any thing to do with concentricity? I'm still using my original herter's press with a RCBS adapter for shellholders for most operations. I also have a C-H 202 (kind of a miniature herters) that I like for seating bullets. I'm not that thrilled with my overall accuracy,--I'm missing something--could it be the presses? Thanks, Steve

Quote:

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Originally Posted by durango

Does anyone find that the brand of press has any thing to do with concentricity?

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Nope, I use both a custom press, and a old Lyman spar T , and have no consintrisity problem with either.

82Boy, just out of curiosity what type of seater are you using and what kind of runout does it give you?

Forester Micrometer, and RCBS Gold medal match.
both give me a range of
0-1/2 to 2 thousand. I like to see it where the needle doesn't move, when I spin them.