Originally Posted by laserflat
BTW any updates on the .375 or .338-500 Jeff?
As with any project there will be design changes made at times to make a product better, either with hard data or theoretically....
I made some changes I felt were necessary...
I got my hands on a batch of the new Jamison 500 Jeffery brass and also some of the 500 AHR brass.. the 500 AHR was designed by Dr. Ken Howell as an improvement over the 500 Jeffery
and the brass is made by Bertram ( 500 AHR = American Hunting Rifle)
the case head/ web was beefed up to better handle higher pressures and the entire length of the body was also slightly thickened, the case is longer then the Jeff and the rim is larger in diameter for better extraction, my entire batch of brass was measured repeatedly and every single case had an identical rim diameter of .585", all other dimensions were repeated satisfactorily, it was very uniform brass. With the rim diameter I do not need to alter the bolt on my Sako M995 which is set up for my 338 Norma Mag based wildcats and they measure exactly the same at .585", hells yeah !!!
I suspect the case head treatment is the same application used by Bertram for Mr. Carlocks 338 Edge brass, which is a very good thing, the original 500 jeffery brass was not designed for todays higher pressures.....
I then cut in half the 500 AHR, 500 Jeffery (original Bertram brass) and the new Jamison 500 Jeffery brass to see how they compare to each other.....
The 500 AHR brass shows a definite improvement over the original Jeff and so does the Jamison stuff, a win win situation for me, I can certainly load my 338 Wolverine and 375 Mjolnir to the same pressures as the 378 Wby and 338 Lapua, with careful loading and gradual workup of course,
I made the decision to run my wildcats with the 500 AHR brass as it has a slightly larger rim and improved case head which will offer me higher velocities and longer brass life coupled with better extraction.... the cases fit the bolt perfectly and also work on the Jamison brass which has a rim diameter of .573" but cycles just fine...
Have some Norma made 500 Jeffery brass on order and will cut it in half to see how it compares to the other stuff...
Mr. Whidden at Whidden Gunworks is making me the dies for the 338 Wolverine and 375 Mjolnir
it's a waiting game now !
I would like to thank all those who were concerned about the safety issues about running a Rem 700 for these cartridges, the info from you and several other areas of input the decision was made not to use the Rem700 for this project, based on the fact that the knowledge of the forum members here far exceeds mine in so many ways...... I will follow safety protocols........
I am now stuck with a fully tricked out factory 300 Rum originally intended for the project,
Rem Factory bbl in 300 Rem Ultra Mag (only 20 rnds fired)
McMillan M40A1 HTG stock in Forest camo
Nightforce 40 moa base
Nightforce 1" 30mm Ultra Light rings
Sightron SIIISS 6-24x50mm MOAR2 scope
Seekins 3.9" detachable mag system and 2 mags (not installed yet)