338 SS split dies and fired ADG brass measuring .006 at the web

[MAD10]

I'm not trying to lecture you and at this point I couldn't care less about your problem. I think it's comical that you are unwilling to draw any correlation from other people who have had similar issues but in different cartridges. I think you are just trying to cover your tracks in hunting down a scapegoat by asking a very direct question and refusing to answer most of subsequent questions from the members here.

I have not had a 338SS experience your problems. And I don't know of anyone who's had an SS of any caliber experience the problems you are having. I have however seen this problem in a 6.5 Grendel but beings that it is not a 338SS I will spare you the time of reading how the problem was fixed. Good luck

It wasn't my personal rifle, but I did work with a 24" 338 SS for a short period of time. I never saw a cracked die, but there was significant case expansion (.005") and lower than expected velocity (2730 fps) with a 225gr bullet.

The owner of the rifle gave me the gun, his loaded ammo using 1x fired ADG bras, his 2x fired ADG brass, 10xunfired pieces of ADG brass, and a set of Hornady dies. He complained that he wasn't getting the velocity he though he should get, and that he was getting hard extraction before he thought he should. He asked me to look at it because I have pretty extensive experience working with high performance wildcats of my own designs as well as others.

I fired his loads and I experienced what I would consider heavy bolt lift and excessive muzzle blast, indicating high pressure based on my experience. I measured the case expansion and got .005" over the measurement for unfired brass. I was able to size the brass without significant issues other than requiring significant effort to run the brass into the die.

I believe he was loading ammunition to excessive pressures trying to reach unrealistic velocities for a case that size. I told him to reduce his loads and be happy with closer to 2675 fps with a 225gr bullet. He chose to keep his loads the same because he believed 2800 fps was the performance he should have seen.

I believe that a lot of the velocities posted for the Sherman Wildcats are a result of running at very high pressures. Some combinations of components can pull it off, others can't. I've ordered 2 identical barrels from the same manufacturer, had them chambered by the same smith, with the same reamer, at the same time, and one showed max pressure at 80 fps lower velocity when using the same components from the same lot.

If you're seeing .006" case expansion you either have excessive pressure, or a sloppy chamber. You're confident that the chamber is accurate, so that really just leaves excessive pressure. It sounds like your loads have exceed the safe working pressures for your system. Sometimes it just works out that way. You either accept the performance you're getting, or you scrap the project and try again.

Good luck

Thank you very much @ Poor_choices. Your write up is exactly what my OP was hoping to find.

With respect to 2675 fps zone …I told Rich when adopting this cartridge if I wanted 35 Whelen or 338/06 I would chamber for it in a long action. In fact I have a 21" barreled 35 Whelen that I reload 225s at 2650 fps. Rich assured me the 338 SS in a 22" barrel would easily reach my goal of 2800 fps and become my "go to" short action rig here out west that has the bullet weight and velocity for taking western big game at 600 yards +

I also have a 338 Edge running 300 gr OTMs so I know exactly what I wanted the 338SS to do.

 

[Poor_choices]

Thank you very much @ Poor_choices. Your write up is exactly what my OP was hoping to find.

With respect to 2675 fps zone …I told Rich when adopting this cartridge if I wanted 35 Whelen or 338/06 I would chamber for it in a long action. In fact I have a 21" barreled 35 Whelen that I reload 225s at 2650 fps. Rich assured me the 338 SS in a 22" barrel would easily reach my goal of 2800 fps and become my "go to" short action rig here out west that has the bullet weight and velocity for taking western big game at 600 yards +

I also have a 338 Edge running 300 gr OTMs so I know exactly what I wanted the 338SS to do.

There are a lot of people who've raised an eyebrow at some of the velocity numbers posted for the Sherman rounds. When I look at the available case capacity, I have doubts unless the pressures are pretty high. I've never seen pressure data on the Sherman wildcats so it's possible they can put up those numbers and I'm just being overly skeptical.