Jamison 408 Chey Tac brass updates....

408 chey tec brass

It'a Lost River 350 gr. soild. I will put some brass in the post office tomorrrow Monday if I had a address.


Thanks
 
Yep, thats the address, I will run her to her limits as soon as I get a couple pieces of brass.

Would even cover the cost of two cases because I WILL be running these cases until the primer pockets let loose. By this I mean, I will work them up to my standard top end pressure load in the TTI cases in my 338 AM whch is a 300 gr SMK to 3400 fps in my 32" barrel. If they handle that with tight primer pockets, I will continue to fire each case over and over until the primer pockets come apart.

If they get me 5 to 6 firings at this level, they are the equal to the TTI cases and are good quality.

If you send me two, I will test the second case at my standard accuracy load which is a bit lighter, 3300 to 3330 fps with the 300 gr SMK and repeat the shooting until the primer pocket is to loose to hold a primer as tightly as should be. They should offer us 7 to 8 firings per case at this level.

TO be honest, if we can get 5 firings with each case with a snug primer pocket, I will be happy and it will be a vast improvement over the current batch of brass I tested.

Let me know, again:

Allen Precision Shooting
#99 Stevenson Rd.
Fort Shaw, MT 59443

Its up to you.

Kirby Allen(50)
 
Test fire 408 brass

Their are 3 pcs in the mail today. I'll check with them to see how many day-months or years etc. that will take to get it.


Happy testing
 
I hope this brass works out, as you will have eliminated the last real impediment to my ordering either the .338 AM or a .375 AM.


JeffVN
 
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)
 
primer pockets

Hi Kirby is the rest of the case standing the pressure?
I have in the past made stainless steel inserts to convert large primer pckets to small they were a press fit and I used some wik in to make sure they stayed in place I also made the flash holes smaler and more uniform.

What I am thinking is you have heaps of barely fired cases the only problem is the primer pockets. get some 5/16 stainless bar and drill a flash hole into the bar grind up a tool to give you a .208" pocket recess and then chamfer the pocket. then part them of.

then out of an old scrap barrel chamber it then turn it to about 1" diameter and have the back of the case just proud and also leave a larger ring at thw back as a stop for your 3 jaw chuck. now place the tool into the mill and cut 3 slots from the back of the chambed holder back leaving 1/2" uncut to keep it all aligned. if possible use a chrome molly barrel so you can now heat treat it to make it a bit like spring steel. now all you have to do is use a uni mill to cut the pocket for the insert and press fit them in with wik in and the pockets should never be a problem again.

Cheers Bill
Australia
 
HOLY CRAP!!!

Sounds like quite the process. If I am going though that much trouble, there will be a 2" long flash tube machined onto the steel cup as well for forward ignition. Not only would internal ballistics be greatly improved, but barrel life and consistancy would also be much improved!!!

Still sounds like ALOT of busy work. If I had a CNC I would think about it.

Kirby Allen(50)
 
I was just contacted by my contact at Jamison and they are sending me a new test lot of brass to check out.

Dimensionally, I guess its the same as the previous lot of brass, only difference is that they have played with the alloy and annealing and now have a smaller grain structure in the brass which they tell me will increase tensile strength.

Seems they are working hard to get us what we need and they should be commended for that. It has been slow but keep the faith. We may still get good cases. If they can get these cases right and offer at least 5-6 firings per case with upper pressure loads then we will be in business as they are set up to put out very large numbers of brass once things are finalized and right.

I must commend them again for wanting to make these cases right before hitting the run hard.

Kirby Allen(50)
 
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