375CT SAAMI Soon?

[orkan]

Does anyone know if SAAMI is close to defining the 375CT spec?

It seems that Cheytac is using one reamer, and most others are using a completely different reamer. (PTG) We ran into the that problem with a customer recently. He has been having sizing issues. His Jamison brass was working fine, but bertram brass was becoming deformed. Initially I thought it was just bad bertram brass. I finally got an opportunity to get over to his house to see what was happening.

Notice the massive crimp in the total FL-sized piece. That is with the die setup so that full contact with the shell-holder is made. The one on the right was with the die adjusted so that there was no contact with the shoulder and only sized the neck. As soon as any shoulder contact was made, the crease began showing up.

The customer purchased their 375CT dies from CheytacUSA.

It is very clear that Cheytac is using an entirely different chamber reamer than Desert Tech is using in their HTI's. Completely different dimensions in the shoulder area. The HTI chamber is more modern in appearance with it's defined shoulder and precise shoulder/neck/body junctions. Clearly, any attempt to resize HTI once-fired brass with a CheytacUSA die will be met with undesirable results. Not having a SAAMI spec for 375CT is clearly not good for the cartridge.

In short, do not buy your dies from CheytacUSA and expect them to work with your HTI.

SOLUTION:
Buy some DTM factory ammo.
Fire it in your HTI.
Order 375CT die set from Whidden Gunworks.
Arrange to have the die custom made, and send in 5 pieces of 375CT brass which has been fired in your HTI.

 

[Dogtown]

It seems as though every couple of years there's a rumor going around that .408CT or .375CT are about to be transitioned out of wildcat status to full SAAMI or CIP approved. That dent is weird though - reminds me of sizing with a die that's over-lubed.

Agreed - the safest way to go with dies for the CT-series is to buy factory ammo and send spent cases to a custom die maker like Warner or Whidden. FWIW, I used CH4D dies in my .408 for years without problems.

 

[wadcutter]

I have the same issue when FL sizing Bertram brass that had been fired in a custom chamber cut with a standard PTG .375 Cheytac reamer. The dies I use are a CH4D .375 Cheytac FL two die set.
Seems I have to use very little lube in the shoulder area or this collapsing of the shoulder will occur.
I have thought about drilling a small hole through my die to reduce lube pressure in this shoulder area when sizing. Any thoughts on this idea?

 

[orkan]

My suggestion would be to replace your sizing die with one custom made from your fired brass.

While excess lube is known to cause issues in resizing, that is most decidedly not a lube issue in the instance shown above. This is a drastic dimensional variance and is absolutely over-working the brass.

The crease happens due to incomplete shoulder contact. Contact starts at the neck/shoulder junction, and at the shoulder/body junction at different times/angles. At least that's how I'm seeing it.

As I said, the Jamison brass being of much higher quality than the bertram, withstands the abuse without an outwardly noticeable crease or problem. That doesn't mean its a "good" thing to be doing.