January 31, 2022 The 30 BR cartridge is an incredible little one. 30 BR shooters will need to neck-up 6mmBR and 7mmBR brass, and then deal with any issues that may arise from the expansion process. One Forum member was concerned about the donuts that can form at the neck-shoulder junction after expansion. Randy Robinett, a respected bullet-maker, offers tips to help with the “dreadful donut”. I measured the neck at 0.329 in my first case. Except for the donut, which measures 0.335?. The groove is located under the donut. It is a known fact that the groove will still be present on the inside of the case when I turn the neck and remove the donut. This means that the base of your neck has a thin-spot,.005 thicker than the rest. Anyone has experienced neck cracking from this ring? “Randy Robinett (who runs BIB Bullet Co.) is one of the “founding fathers of the 30 BR. He helped to prove and popularize 30 BR benchrest score shooting. Randy gives this advice about 30 BR case-forming. While the neck-base is thinner than we originally thought, it’s not a problem if one doesn’t cut too deeply into the shoulder. Thirty (30) cases were used in my original 30BR chamber to fire 6,400 rounds through it. The cases were not annealed and there were no case failures, neck separations or splits. The case-necks were sized with a.324? from the beginning to a loaded-round neck diameter. neck-bushing. Fire-form is the best way to avoid the ‘bulge’. There are several methods that can be used. Too deep into the shoulder can cause case-neck separations. Although I have seen it, I have not personally experienced it. The original barrel was used in the last registered BR event. It produced a score of 500-27x and a second-place finish. This is a good score for 6K shots and a little over 200 firings per case. AccurateShooter.com has a 30 BR Cartridge guide.
Our 30 BR Cartridge Guide has more information about case-forming. Here’s a quick excerpt from that page: Some tips provided by Al Nyhus, benchrest for score, and HBR shooter Al Nyhus. 30 BR Case-Forming Procedure.
The necking-up of 6mmBR or 7mmBR brass is what creates the 30 BR cartridge. This can be done in multiple stages or one-time. Either an expander mandrel, like Joe Entrekin, or a tapered button in regular dies can be used. I personally use the Redding tapered expander buttons, part number 16307. This allows you to expand the necks by 6mm to.30 ca in one pass. It works as long as the mandrel is lubricated and the inside of your necks are lubricated. I have also used the Sinclair expander bodies with a series of larger mandrels. However, this is more work and the necks are straighter with the Redding tapered buttons. This button can be used with any Redding die with a sufficient inside diameter to accept the BR cases without any case-to–die contact. Before firing the first time, don’t worry about how straight your necks are. They will straighten out fine if you give them around 50,000 psi. If there is sufficient light crush-fit in the chamber, I recommend that you do not place the bullets into the lands during the first firing. Lapua cases will be approximately. 1.550? 1.550 to 1.520? After being necked up at 30-caliber, I trim to 1.500. With the 1.520 length chambers. After the first firing, I don’t deburr or uniformize the flash holes. Ron Hoehn flash-hole deburring tools that index on the primer pocket and not through the case mouth are what I use. — Al Nyhus Similar Posts:Tags: 30 BR, 30BR, 6mmbr, Al Nyhus, Case Forming, Fire-Forming, Score Benchrest
