280 Rem Brass for 7mm Backcountry: A workaround idea

[Halligan]

Hi all,
I searched around here and the rest of the internet, so to my knowledge, this topic has not been brought up, and if I missed it, please post the link. As many of you are no doubt aware, the ability to reload the 7mm backcountry is still up in the air as reloading equipment, data, and processes are slow to roll out. This has been a cause for pause for many in the market for a new rifle (like yours truly), with the additional worry of ammo availability also cropping up.

This said, I got to thinking (I've been told this is dangerous by my girlfriend) and it occurred to me that the case is effectively a slightly modified 280 Rem. Therefore, if one could resize 280 Rem brass to 7mm backcountry dimensions, it would give owners of these rifles a much bigger pallet of load options that would be perfectly fine for big game hunting (just using published 280 load data).

Thus, two questions for the fine mad scientists here:
1) Would resizing the brass be doable (assuming yes based on specs, but I'm a novice in this realm)?
2) Do you think that you/others would be more comfortable buying into the cartridge now, knowing that there is a brass case "backup" option, which offers both perfectly adequate big game performance and protection against any steel case ammo shortages from Federal?

 

[khuber84]

You're gonna have inital trim them to 2.410, then push the shoulder/neck junction back with the 7bc die until they chamber with a lil bit of resistance(approx 0.060"), possibly trim again, then fireform. You just made about 0.060 of shoulder brass into neck brass. This new material will likely be thicker than the rest of neck brass. That'll need turned down to the same spec as the rest the neck to eliminate donuts and inconsistent neck tension. Cases that are blown out, will likely shorten up a fair bit due to brass displacement in the larger diameter shoulder area.

The 280 ackley diameters are much closer to the 7bc. I'd see if someone on the forum has a handful of old cases with loose primer pockets, you could test running them into the 7bc die, reshape the shoulder to 30° and push the shoulder neck junction back 0.040" till they chamber. Once again you'll need to neck turn the bottom of necks for consistency. You'll definitely want to put a good annealing on the case prior to doing this.

The 7bc has a few radius in the chamber that aren't present in other modern chambers, one at neck shoulder junction and one at shoulder body junction. I'm sure this is to help the case extraction with the high psi.

At the end of the day, you're now shooting a brass case designed for roughly max 65k psi. The new brass 7bc cases you made, affectively have less volume and now equal pressure rating as the 280 ackley you may have started with. Equal psi at less capacity equals less velocity. If you want brass cases, just buy a 280 ackley, it'll be much easier and it'll perform better than the brass 7bc cases.

 

[Scottf270]

The steel case is what allows the Backcountry to be what it is. While modifying regular brass cases may chamber, you are giving up the strength of the steel case. I see no gain at all and nothing but risk.