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Post by AxeHandle on Feb 28, 2019 17:48:28 GMT -5
Remember when there was no such thing as 7mm BR brass? Not hard to find. They simply did not make it. To run your 7mm BR XP-100 you bought BR brass which was a small primer 308 case and then used a case forming die set to make your 7mm BR brass. Somewhere back in the shop I have a case forming die set. We forget how good we have it. These ARE the good ole days...  |
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Post by Encore64 on Feb 28, 2019 19:18:56 GMT -5
The 308 Brass used was made thin on the upper half to ease forming and provide uniform neck thickness.
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Post by bradshaw on Feb 28, 2019 19:54:03 GMT -5
Remember when there was no such thing as 7mm BR brass? Not hard to find. They simply did not make it. To run your 7mm BR XP-100 you bought BR brass which was a small primer 308 case and then used a case forming die set to make your 7mm BR brass. Somewhere back in the shop I have a case forming die set. We forget how good we have it. These ARE the good ole days... ***** The Remington XP-100 7mm Bench Rest Remington is a product of the cartridges creator, Jim Stekl of Remington R&D and Bench Rest Hall of Famer. The prototypes brought to the IHMSA 1980 International Championships by Jim Stekl and Remington PR man Dick Deitz had barrels just under 15-inches. The barrels were slightly heavy, and hole spacing for iron sights needed adjustment to comply with the 15-inch sight radius rule on Unlimited guns. The barrel would have to be lighter to make the 4-1/2 pound Unlimited weight. Stekl and this shooter got together after the match to sort out details. I also insisted the pistol make weight with a George Petersen Thumbhole Centergrip from Western Gunstock; fashioned from walnut, which of course weighs more than the Remington’s Buck Rogers stock made in two halves from Dupont Zytel. Perhaps no one was more infuriated than Remington’s own Jim Stekl when Remington forced shooters to wildcat brass. (This story continued for years with Stekl’s 6mm BR Rem and .22 BR Remington.) Using RCBS 4-die case forming dies, it took me 8 hours to make my first 100 7mm BR cases. It is much easier to form the 7mm Talbot (7mm/308x1.75”), than to form the 2-inch .308 Winchester case down to the 7mm BR’s 1.5-inch case. The Remington .308 brass mentioned by encore64 eased the job a bit, but hardly eliminated the tedium. Instead of turning necks, the RCBS case forming dies have an excellent neck reaming die, with reamer. When Remington released the XP-100 7mm BR Remington----without brass or ammunition----the door was open for the shooters to re-chamber to Elgin Gates' 7mm IHMSA (7mm International) and load 7mm IHMSA brass made by Federal Cartridge. After getting swamped on the firing line by Gate’s 7mm IHMSA, the 7mm BR made a comeback, and many custom Unlimited pistols were built for it. David Bradshaw |
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Post by onegoodshot on Feb 28, 2019 22:57:19 GMT -5
Can I use the Lapua 6mmBR Norma brass?
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Post by bradshaw on Feb 28, 2019 23:31:38 GMT -5
Can I use the Lapua 6mmBR Norma brass? ***** Someone who has done it may chime in. Lube and a PROGRESSIVE EXPANDER may take it from 6 to 7 without splitting. Then you are home. Medium powders perform. The preeminence of IMR 4895 and H4895 in cartridges of this class holds true in 7mm BR Rem. 4895 is a guru of versatility. IMR 4198 is fastest powder I would use; in fact, 4198 is a guru among faster stick powders. Silhouetters used a spectrum of propellants in this burn range, both ball and stick powders. David Bradshaw |
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Post by sixshot on Feb 28, 2019 23:58:01 GMT -5
I had the first 7 IHMSA ever built.
Dick
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Post by onegoodshot on Mar 1, 2019 6:35:25 GMT -5
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Post by AxeHandle on Mar 1, 2019 7:16:56 GMT -5
A 6 (.264) to a 7 (.284) shouldn't be that much of a stretch. I'm thinking you should buy a 6mm BR just to be on the safe side. Something like this Encore with a Bullberry 6mm BR barrel and full Bullberry wood would shore up that weakness in your set..  |
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Post by bradshaw on Mar 1, 2019 8:04:54 GMT -5
"And back to the nickel 7mm br brass that I found. How do you guys feel about it vs necking up the 6mm Lapua?"
----onegoodshot
*****
I would avoid nickel plated brass for the BR’s in general, and not use it to neck up or neck down. Nickel lacks the elastic and plastic properties of brass and, I was told many years ago, weakens brass. Nickel’s corrosion resistance is not at issue. Any dirt will incise nickel and I believe etch a sizing die faster than brass.
Wash your found 7mm BR brass, check for stretching above the web, then size to your chamber. If your Full Length sizing die fails to SIZE the case down enough to freely chamber, you may want to discard the nickel cases. If it chambers freely, make a DUMMY ROUND to check for easy chambering. Nothing rockets chamber pressure faster than a case neck wedged between chamber & bullet. The neck cannot release the bullet, so the powder thinks it’s in a hand grenade, not a rifle chamber.
David Bradshaw
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Post by sixshot on Mar 1, 2019 12:05:18 GMT -5
That last sentence gives me goose bumps just reading it because many people don't realize how dangerous it really is. If that bullet can't release & you get a pressure spike things can get crazy in a hurry. One of the worst offenders out there is the old 220 Swift. One way to check if the necks are too thick is to try & slip a bullet into a fired case that hasn't been resized. You really had to be on your toes with 220 Swift brass.
Dick
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