Bumping the shoulder on a 7mm WBY Mag?

gpjohnson

New member
I am new to reloading and own a 7mm Weatherby Mag. I have a set of RCBS FL dies for 7mm WBY Mag. I also purchased a Wilson Adjustable Case Gage for 7mm WBY Mag. I set the case gage as instructed using a once fired, decapped case to set max head space. I set the FL die as instructed and resized some cases. When I checked the cases with the case gage, they all were still sitting at the max. How do I set the die to move the shoulder back? I understand that head space is measures from the belt, but do I want my cases tight in the chamber? Thank you for your time and attention.

Gil Johnson
Herman NE
 
Originally Posted By: gpjohnsonI am new to reloading and own a 7mm Weatherby Mag. I have a set of RCBS FL dies for 7mm WBY Mag. I also purchased a Wilson Adjustable Case Gage for 7mm WBY Mag. I set the case gage as instructed using a once fired, decapped case to set max head space. I set the FL die as instructed and resized some cases. When I checked the cases with the case gage, they all were still sitting at the max. How do I set the die to move the shoulder back? I understand that head space is measures from the belt, but do I want my cases tight in the chamber? Thank you for your time and attention.

Gil Johnson
Herman NE


Think you'll find headspace measure's to the belt, not from. Problem with a lot of belted case's is that belt. The headspace can be right and you can still separate case heads. To overcome that you partial re-size. Then the shoulder is moved just enough to allow the case to chamber and not stretch to much. The term bumping the shoulder is a bad word. You cannot bump the shoulder without moving it. What is done is the dies is set to full length size the case just enough to allow it to chamber freely. Some guy's like the shoulder to rub a bit in the chamber, I don't. Once the die moves the shoulder at all, the case is full length sized to some degree. I think the best term to describe it is partial sized. If the die is set so that the shoulder doesn't get touched but most the neck is sized, it's neck sized. If you neck size with your FL die till the case will no longer fit the chamber, at that point you can re-adjust the die just a bit at a time till the case chamber's easily. It will not change the headspace on the belt but in effect moves the headspace to the shoulder on a sloppy chamber, pretty much end of early case failure due to head separation. Forget the belt, make the case fit the chamber. I even do that with my rimless case's. Every set of dies I have is dedicated to one particular rifle and adjusted to it's chamber and left there. I found in the past few years that I have two rifles in the same cartridge at the same time, never done that before. But each of those rifle's has it's own set of dies! The ammo from one set will chamber in both rifles. The ammo from the other set won't. Simply a difference in the chamber's. Set the FL die the way directions say to set it and the ammo should work in every chamber for that cartridge. We reload according to directions to min standards, that means no chamber will be cut smaller. Reamers are stopped being used when they have worn to cutting a certain size chamber which is larger than standard but within spec's.
 
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Thank you Don. I replied to an earlier question, the cases do chamber, but are a little snug compared to factory ammo when closing the bolt.
 
I know everyone has a little different interpretation of what "a little snug" is but if it chambers fine and only has a tiny bit of resistance closing the bolt, for me, that would be preferred because it sounds like you're headspacing off of the shoulder and not the belt which should result in better accuracy.

If you have a set of calipers and a shoulder bump/headspace gauge measuring them so they are all the same length to the shoulder will also yield better results for you as well.
 
I use an over size ogive gauge, I think 33 caliber to measure off the shoulder as a headspace measuring gauge.

From "snug" fit to an easy fit, is perhaps 1/16 turn on your die body.

Forget the Rim like it does not exist, you set the die off the headspace length off the shoulder dimension.

A snug fit case may leade to tougher extraction, enough to break your concentration on a follow up shot that is needed....bad ju ju.

Brass springs back from sizing trying to achieve the dimensions of the chamber of the gun it was fired in, expecially in large magnums. This springing back out can happen in a few weeks or a couple of years. The amount of the spring back depends on the size of the chamber the brass was fired in.

I have ammo that has been loaded for 20 years this is ok, then 7 mags that sprung back out from two years ago and now those 7 mags are snug fits because I bought a butt load of brass once fired.

So, for big magnums, I keep my ammo fresh that was shot in large factory chambers.

You will have great success with the 7 Weatherby, especially with 160g bullets, R#26, and fed 215's.
 
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