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Primer pockets both measure .209 on fired and unfired brass
Case Rim Expansion - 6.5 Saum
- Thread starter gut_pile
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Bob Wright
Well-Known Member
I don't own any DBM's but I'm curious to know why the sheet metal body of the mag is that close to the rim diameter. .005 clearance is not what I would think is reliably functional. If it's the feed lips then that would be the problem to be solved. With the shell holder issue, there are others to try. Borrow a buddies?
Lastly, I would try sanding some of the rims to clean up any burrs from extractors etc. and retry those in the mag and shell holders.
Lastly, I would try sanding some of the rims to clean up any burrs from extractors etc. and retry those in the mag and shell holders.
High pressure- These cartridges run right on the edge of 75,000 psi. where brass will no longer spring back, after firing.
Soft brass may be another issue.
Buy new brass. Load less powder.
I can't help but think the brass is suspect.
Definitely measure a bunch of "new" cases to start with.
Especially if the pockets aren't changing diameter.?
Definitely measure a bunch of "new" cases to start with.
Especially if the pockets aren't changing diameter.?
BrentM
Well-Known Member
I had to slightly open up my shell holder opening for the Sherman improved PRC brass to fit.
Case heads and case rims can expand when cases are defective or over-pressured. I've measured case head expansion multiple times in the past 15 years. But in every instance, the primer pockets have also expanded. When primer pockets expand, the case web and case head also expand.
If the primer pockets have not expanded to a larger diameter than on unfired virgin cases, then it's very unlikely excessive pressure is the primary cause of the case heads not fitting inside your shell holder. Case rims often aren't exactly 100% round. Sometimes I've rotated the case heads slightly and they will then enter into the shell holder. I've also mounted cases in my drill press and slightly reduced the diameter of the case head, with a fine toothed file and some sand paper, until they slip into the shell holder.
You can buy pin gages on FleaBay and Amazon to check your primer pocket diameter and test for loosened primer pockets (expanded primer pockets). They aren't expensive. I use them to track both small and large primer pocket diameters of my casings.
I'd try another shell holder, or two. You might find your's is simply on the tight end of manufacturer's tolerance. Also consider buying a different brand of brass. I've had some inconsistencies with Hornady brass, in years past. Especially their 375 Ruger cases.
If the primer pockets have not expanded to a larger diameter than on unfired virgin cases, then it's very unlikely excessive pressure is the primary cause of the case heads not fitting inside your shell holder. Case rims often aren't exactly 100% round. Sometimes I've rotated the case heads slightly and they will then enter into the shell holder. I've also mounted cases in my drill press and slightly reduced the diameter of the case head, with a fine toothed file and some sand paper, until they slip into the shell holder.
You can buy pin gages on FleaBay and Amazon to check your primer pocket diameter and test for loosened primer pockets (expanded primer pockets). They aren't expensive. I use them to track both small and large primer pocket diameters of my casings.
I'd try another shell holder, or two. You might find your's is simply on the tight end of manufacturer's tolerance. Also consider buying a different brand of brass. I've had some inconsistencies with Hornady brass, in years past. Especially their 375 Ruger cases.
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Thanks for the help
