Post by Lee Martin on Aug 16, 2009 21:57:05 GMT -5
Over the years, I’ve received a lot of questions on how to form 401 Herters Powermag. Though it can be done on 30-30 Win, I prefer to use 41 Magnum.
I formed 100 today and thought I share the process. 41 Magnum is 0.434” in diameter and 401 Powermag is 0.426”. While 0.008” doesn’t sound like a lot, you can’t effectively do it with a Herter sizing die. It’ll squeeze it down until you get into the web, creating a step. At that point, you’re forcing the brass too much and the rim will likely rip when trying to pound it out of the press. Some folks use this method, then lathe turn the 0.008” off the web region. Here’s a photo of one I received with a gun I just bought:
Notice the turned portion towards the bottom of the shell. Personally, I don’t like this method because it weakens the case. Plus the section you size in the press is hard on the die.
When I bought my first 401 years ago, I drilled a plain, unthreaded 0.426” die out of graf-mo:
The piece on the left is used as a punch base. The die is quite simple to make and will easily reduce 41 cases to 0.426” on a press:
An old Chevrolet exhaust valve is used to punch them out:
From there, the cases are trimmed to 1.270”. While 1.275” is the official spec, I usually go 0.005” extra. Now some Powermags have cylinder recesses big enough to handle the 41 Magnum rim (which measures 0.487”). The 401 I just bought doesn’t however, so the rims are lathe turned to 0.477”.
Left – Formed 401 Herter Powermag
Right – 41 Remington Magnum
I’ve also been asked about what bullet molds to use. I have some good 10mm sets, but find it easier to swag 41 caliber to 10mm:
Left – swaged 230 grain Keith 41. Sized to 0.401”
Right – 41 caliber Keith. 230 grain
I hope this helps and if you shoot these old guns and have questions, drop me a line at lee@singleactions.com.
-Lee
www.singleactions.com
PS – if I find time over the winter, I may be willing to sell formed 401 cases if there’s interest.
I formed 100 today and thought I share the process. 41 Magnum is 0.434” in diameter and 401 Powermag is 0.426”. While 0.008” doesn’t sound like a lot, you can’t effectively do it with a Herter sizing die. It’ll squeeze it down until you get into the web, creating a step. At that point, you’re forcing the brass too much and the rim will likely rip when trying to pound it out of the press. Some folks use this method, then lathe turn the 0.008” off the web region. Here’s a photo of one I received with a gun I just bought:
Notice the turned portion towards the bottom of the shell. Personally, I don’t like this method because it weakens the case. Plus the section you size in the press is hard on the die.
When I bought my first 401 years ago, I drilled a plain, unthreaded 0.426” die out of graf-mo:
The piece on the left is used as a punch base. The die is quite simple to make and will easily reduce 41 cases to 0.426” on a press:
An old Chevrolet exhaust valve is used to punch them out:
From there, the cases are trimmed to 1.270”. While 1.275” is the official spec, I usually go 0.005” extra. Now some Powermags have cylinder recesses big enough to handle the 41 Magnum rim (which measures 0.487”). The 401 I just bought doesn’t however, so the rims are lathe turned to 0.477”.
Left – Formed 401 Herter Powermag
Right – 41 Remington Magnum
I’ve also been asked about what bullet molds to use. I have some good 10mm sets, but find it easier to swag 41 caliber to 10mm:
Left – swaged 230 grain Keith 41. Sized to 0.401”
Right – 41 caliber Keith. 230 grain
I hope this helps and if you shoot these old guns and have questions, drop me a line at lee@singleactions.com.
-Lee
www.singleactions.com
PS – if I find time over the winter, I may be willing to sell formed 401 cases if there’s interest.
