If you aren't familiar with Sherman Wildcats. Rich sells his 338SS brass with a 7mm neck and you are required to neck up. The amount of shoulders I was randomly collapsing was alarming. I was following known practices such as using a three step process to achieve the .054 of neck expansion required. Specifically carbide mandrels in .30 cal, 8mm and 338. I chamfered and deburred the brass and lightly lubed both the mandrel and inside the case neck. I should note my failures were at the 8mm step and on the first attempt each time.
I spoke with Rich Sherman after I had expanded all my necks with the .30 cal mandrel without issue. He suggested I try my 338SS FL sizing die and keep the sizing button on the stem to open the necks to 338. Well **** it worked perfectly!
I treated the brass just like I was FL sizing a piece of fired brass, with one exception, I did not run the brass fully into the die I only went just enough to feel the neck run over the button. I will say it is wise to check the sizing button after you've sized a few necks to be sure it's not threading off the stem. Also runout was 2-3 thou.
NOTE: The mandrels were Sinclair carbide expanding mandrels. IMO it seemed the short travel was too abrupt without the case being supported as it was in a the FL die. Verse much longer mandrels, such as 21st Century mandrels, which are longer and have a more gradual taper. The 8mm mandrel taper was .250 to .322 in a very short distance so that may have something to do with it. However, I had no issue with the 30 cal mandrel of similar taper and length.
Disclaimer: Using a FL sizing die to expand necks might be a common solution but it wasn't for me. I only used "like" caliber mandrel diameters for neck tension and removing dents - to see shoulders collapsing was co$tly.
Sincerely,
I spoke with Rich Sherman after I had expanded all my necks with the .30 cal mandrel without issue. He suggested I try my 338SS FL sizing die and keep the sizing button on the stem to open the necks to 338. Well **** it worked perfectly!
I treated the brass just like I was FL sizing a piece of fired brass, with one exception, I did not run the brass fully into the die I only went just enough to feel the neck run over the button. I will say it is wise to check the sizing button after you've sized a few necks to be sure it's not threading off the stem. Also runout was 2-3 thou.
NOTE: The mandrels were Sinclair carbide expanding mandrels. IMO it seemed the short travel was too abrupt without the case being supported as it was in a the FL die. Verse much longer mandrels, such as 21st Century mandrels, which are longer and have a more gradual taper. The 8mm mandrel taper was .250 to .322 in a very short distance so that may have something to do with it. However, I had no issue with the 30 cal mandrel of similar taper and length.
Disclaimer: Using a FL sizing die to expand necks might be a common solution but it wasn't for me. I only used "like" caliber mandrel diameters for neck tension and removing dents - to see shoulders collapsing was co$tly.
Sincerely,