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Posted: 5/25/2017 3:34:02 PM EDT
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I just picked up a nice older Remington 700 bdl in 7 mag. I'll start playing with different powder and bullet combinations. That's not my concern.
What differences in tools and technique are involved in loading a belted magnum cartridge? |
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When I loaded 7mmRM, I simply used a partial neck size....
After the first firing, I'd leave the die adjusted about 2 turns "high" on the press. I'd color the neck with a sharpie or smoke it with a match, then run it through the die. You can see what was, and what was not sized. Slowly adjust die down until you are close to the shoulder. Ideally, I'd just barely kiss the shoulder, without actually reforming it. the end result was a fire formed case that was a perfect match for my chamber. Essentially, pretty much a max case length case for my rifle. For any serious purpose use, cycle each case through the action to ensure it closes without issue. Yes. It was redneck and low dollar. But it worked good. I still use the technique on other rifles that headspace on the shoulder..... I fire form 280Rem into 280 AI. Cases are all neck sized only after that. The result is the same |
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Actually "short sizing" the belted magnum instead of neck only sizing is a really good option if it works for you because short sizing still reduces the body size some.
If you are unfortunate enough to have a belted magnum with excessive space between the bolt face and where the belt would traditionally headspace you are not going to be able to reload it unless you either have it fixed or buy a special collet die that resizes the bulge directly in front of the belt. The 7mm RM is a very good caliber and very versatile. Load it with 139gr or 140gr boat tails and it will amaze you how flat it shoots and it doesn't really recoil that bad. Motor |
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Thanks for the suggestions. More questions...
Is there any point in working up loads with new brass if the case dimensions change so much after firing? It seems the best load for the gun will be with brass formed to the chamber. Say I start with new Nosler brass... how do I get to the once fired part without wasting money? |
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The future money pit in question, as received from my friend. I paid $350.
Attached File |
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Quoted:
Thanks for the suggestions. More questions... Is there any point in working up loads with new brass if the case dimensions change so much after firing? It seems the best load for the gun will be with brass formed to the chamber. Say I start with new Nosler brass... how do I get to the once fired part without wasting money? After the brass has been fired in your chamber you can measure it like Dryflash showed in his picture. Then adjust your die for future operations. I wouldn't expect the difference to matter for load development just for improving brass life, but someone with more knowledge than I will probably be along shortly. |
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I wouldn't expect too much difference. Our newest 7mm RM came as a surprise gift for my son from his uncle about 5 years ago.
I started a few grains below Sierra's "accuracy load" just to watch for pressure which ended up being fine at their accuracy load using 150gr BTSP. I used once fired brass that I got free (handed to me fresh from being fired) from a fellow at the range some time before that. I adjusted my die for cam over (RCBS Rockchucker II) which BTW is still how it's adjusted. The rifle shot a one inch at 100yards with 3 different people shooting the 5 rounds. After reloading the accuracy remains the same. Yeah I agree with the die set for full cam over I am lucky I'm not having any brass issues but I'm not complaining. In fact I'm happy. It takes all the guess work and measuring out of the equation. A couple weeks ago we shot the rifle at a 300 yard range with 139gr BTSP. After adjusting zero there was nothing on the berm that was safe. If it could be seen with the 12x Leopold it was toast. What amazed me the most was how quickly the bullets were arriving on target. These are not little 55gr or even 75gr these are 139gr. Very eye opening. Motor |
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Quoted:
Thanks for the suggestions. More questions... Is there any point in working up loads with new brass if the case dimensions change so much after firing? It seems the best load for the gun will be with brass formed to the chamber. Say I start with new Nosler brass... how do I get to the once fired part without wasting money? Then I'm loading cases fired in my chamber and can fine tune my load or loads. For a fun, light recoil load try the Hornady 139 gr Spitzer. I have found this bullet is quite accurate. In 7mm mag and 7-30 Waters. |
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