Just got through reading Richard Mann's article on the 7mm JRS in Handloader. Remembered reading Jon Sundra's hunting stories using this wildcat in Africa. Always wanted to try one. I believe that they were the inspiration for the Hawke wildcats but could be mistaken. Have any here on the 'fire used this wildcat?

I had one once. A stainless 700 KS that was skeletonized. Really nice package.

7Mag velocities.

It's a rifle I wish I would have kept.

Help me out here, I haven't read the article you mention and I've slept since I read an article Sundra wrote about it back in...maybe the 1990s.

Wasn't it essentially a 280 A.I. with a shorter neck? Velocity with 150 or 160 grain bullets? Or even 140s?

Now I need to go dig that magazine out!

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I think you're right ...

7mmJRS was a 280 Rem with a 35 degree shoulder pushed out to allow a 0.300" neck. It gave about 7.5% more capacity than 280 AI. Ballistics were very close to matching 7mm Mag velocities with 120 - 160 gr bullets with out a belt.

Dead on Prowlr (working from memory).

I'd like to know what the actual pressures were.

No way of knowing for sure but the capacity is 71 grains as quoted from the Handloader article which is 8 grains greater than the 280 (12.6%). That comes close to the capacity of the 7 mag. So I would think that at 63-65k it should tread close to the 7 mag. My only knowledge of this wildcat is from articles FWIW.


Note the correction of the % capacity from the article.

mathman

Did some quick figuring from the 7th Nosler Reloading Guide.
7mmMag 160 gr bullets 24" barrel
6 powders gave velocities ranging from 3008-3077 fps
Average vel was 3045 fps

280 AI 160 gr bullets 26" barrel
7 powders velocities ranging from 3002-3045 fps
Average vel was 3022 fps
Subtracting 50 fps for the 2" longer barrel = average vel of 2972
using MD's 1/4 rule - 1/4 of 7.5% (greater capacity of JRS than 280AI) = 1.875% or 0.01875
thus 2972 x 1.01875= 3027.7 fps for the 7 JRS.

Just math but seems like it could come real close to 7mm Mag velocities with 160 grain bullets at reasonable pressures.