376 Steyr based cats

[jenks]

The smith featured in the TC Encore gun of the week article last week,Mike Sirois/ OTT) has worked up these wildcats for me. We are also working with these on the Encore platform. I havent done much work with the 30 cal version but the .264 and .338 are working out nicely. We took most of the body taper out and gave it a single radius shoulder. 308Win on left for scale;

22" barrel w/ custom brake for 338 version:

 

[M9Powell]

I'm interested in a 6.5 or maybe a 7mm based on the 376 steyr. I basically want a 6.5/284 or a straight 284 with a little more capacity, a more conventional rim & a longer neck. What does the radiused shoulder do? I know weatherby has used a radius for years but I thought it was just a marketing gimmick. Does it have a practical purpose? Who makes your form dies? Thanks M9

 

[jenks]

M9, Roy W's was a double radius...we decided to try a single thinking that it may improve the gas flow dynamics, knowing that it would be next to impossible to determine if it actually does.
We also did it just because we could with the EDM machine.
Case capacity of H2O runs just at 74.2 grains. I trim my cases to 2.340" 59.0 grains of H1000 lit by a CCI250m will push the 140Sierra Mks at an average of 2953fps out of my 26" tube at 78 degrees with no pressure signs. 57.0 grains of RL-22 over a Fed210M will run the 140 Amaxs at avg. 3034fps.
Mike Sirois who does the barrel work also EDMs the dies...either from a case hardened blank or by way of modifying a 264 Win mag die.

 

[M9Powell]

What neck length did you end up at with the 6.5 version? Thanks
M9

 

[jenks]

.280"

 

[M9Powell]

I'm wanting around .300"-.325" I think. Do you have any case drawings? I don't want to reinvent something already done.
I'm thinking of using the same shoulder dia & angle as the 284.
Thanks M9

 

[jenks]

M, I did up some drawings in the "Load from a Disk" software depicting a standard shoulder...since the software wouldnt draw the radius. I just havent been able to figure out how to output the drawings. If I can figure it out I will email you one.

 

[Wild_Bill]

Hi J i am interested in making a 338-300RUM improved so i am interested in your radiused shoulder design. I was thinking of minimum body taper with a full case width radius shoulder to try sompthing diferent. How do your cases form and size do you have any trouble setting the shoulder back when sizing. I believe i should be able to get a reamer made bu David Kiff but the sizing die would be an issue i have RCBS 338 RUM dies i could send to be EDM'd do you know what it would cost to have the dies machined? i can then have them Nickle Teflon coated afterwards. I also am thinking if it is not possible mabe a 60 degree shoulder as SSK is still making them fir contenders and they are having no troubles in a break open rifle.

Cheers Bill
Australia

 

[jenks]

WB,
I haven't run into any issues yet with the sizing. The chamber to die tolerances are so tight that there is very little working of the brass. Some of the 338 cases are on their 4th loading cycle and I have not been pushing the pressure envelope with the loads. I am unable to respond to the cost issue as it is not my shop but if you have the time go check out:
Click Here


Mike will gladly discuss you project with you.

 

[M9Powell]

Midway is now selling PTG reamers for a 30/376 Steyr. Anyone have any specs or chamber drawings on this critter. I just bought a used Obermeyr 308 barrel & am thinking about rechambering it to this. I'd like a steeper shoulder angle than the 376 has. M9