7mmWSM bushing size- mag fed

[AndyW]

I will be loading Win brass and need to know what size bushing to order for a mag fed hunting rifle, SAAMI chamber. I measured a few factory loads and they were .313 average. Order a .310?

Thanks.

 

[CraigB]

I have been working with a 7 WSM for the past year. It's my first non-varmint/magnum caliber. I normally load at or near the lands in most of my guns, but after reading the article by Eric at Berger bullets, I tried jumping at varying distances. I ended up at around a 10th jump with a Sierra 168. This may help if you have mag length limitations. I neck turned my brass, so my loaded rounds are just over .311. After using a neck sizing die, which resulted in more runout than I could live with, I ended up using my full length sizing die. I'm not exactly sure what the heck was going on with my neck die, but it seemed to me that the die was 'loose' near the base and did not support the case enough to keep it straight. My outside diameter after using the F/L die is approx. .310. The brass hardens pretty quick in this caliber, which I'm not used to either. With this set up I'm getting under 1/2 inch at 100,3 shots). My current load is 63.4 gr. RE22 with a 168 Sierra, Fed Match Mag primer, and about a 10th jump. Hopefully somebody with more experience with the 7 WSM will chime in on this. I would buy several bushings, and start with 2-3th neck tension. There was an interview recently in the daily bulletin that talked about neck tension, I think they recommended 1th tension, but I'm not sure that applies to magnum type rounds.

 

[AndyW]

Well I am bulding this gun as a flyweight sheep gun so not really sure how far to take things, ie- neck turning, etc..

I will start with a .310 and order a couple more smaller and then I have the option of a neck clean up and a bushing that will still give me enough squeeze when the bullets are handled roughly and pushed through a mag.

Thanks,