I got the three test cases from Stephen Newberry late last week and was able to get them formed up and run through the 338 Allen Magnum to see how they would stand up to upper end pressure loads.
Simply put, they are identical to the original post on the latest brass I tested. I measured the primer pockets to be around 0.2073" in diameter on average, same as the #200 lot brass I just tested. All other dimensions were also identical.
For comparision, the TTI cases will take 147.0 gr of H-50BMG under the 300 gr SMK for 7 firings total. This is my max working load for my 338 AM.
The first four firings on the TTI cases have very quality primer pocket fit. Firings 5 and 6 loosen up much more and on the 7th firing you are wondering what is holding it in there but none have produced any gas leakage in my testing with over 200 cases tested.
My standard load with the TTI cases is generally in the 143-144 grain range with same bullet. Velocity is generally in the 3300 fps range or slightly below it but very close. This load will get you 7 firings with good primer pocket tightness throughout, just that at 7 firings, the cases get tempered and with the surface area on the 338 AM case, extraction becomes to sticky and the cases need to be retired.
The Jamison cases I tested for Stephen, I started with 145.0 gr and on the first high pressure firing, the primer pockets loosened DRAMATICALLY. In fact after the second firing at this level they were looser then I would use. I still fired it a third time and I did get mild gas leakage.
Dropped to 142.0 gr and tested another case. This offered me another firing. On the 4th firing, there was no gas leakage but the pockets were tighter then what I would like to recommend to customers.
Dropped to 140.0 gr and the results were the same as the 142.0 gr load.
Now, from talking with Stephen, he was told to load his 375-408 CT to 3100 fps with a 350 gr solid in a 32" barrel. To me personally, this sounds like a VERY mild load as I can drive a 350 gr ULD RBBT to 3200 fps in my 338 AM in a 32" barrel but the solid will develope less velocity for sure.
It may be just that the Chey Tac boys are recommending loading these cases to much lower pressures they the TTI cases have easily handled in the past.
So, from what I see, the cases Stephen has now are the exact same ones I tested in my original post. If you can live with reducing your loads a bit and getting 4 firings per case, these will get you shooting your rifles but realize that the primer pockets will be much looser then your probably used to but if loaded properly, I did not see any gas leakage, just have to drop the FPS a bit.
Hopefully they will get us some tighter primer pockets and that will help to some degree, at least getting us another 1 to 2 firings per case and then it would be acceptable. To get 4 firings per case is a bit hard to swallow with the price of each case but 5 to 6 would be getting acceptable.
Believe me, we are still working hard on Jamison to get us what we need.
Kirby Allen(50)
