need some help on the topic of how to correctly bump the shoulder back on .308 Win. brass. I use a lee collet die to neck size but most of the cases are starting to make it very hard to close the bolt.What is the correct way to do this short of just full length sizing again? or is that what needs to be done? Should i have a die dedicated to that purpose? will it have a great affect on the accuracy of the case?
- Thread starter 1maxhunter
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They do make a shoulder bump die that would be the easiest, most repeatable way to do it. However, If you have a FL die you can use that to do it.. Most people screw the die all the way in until it touches the press ram. This will make it chamber in anything, but it it sizing the brass to the max. To be honest I very rarely ever size it that much.
If your FL die has an expander, take it out. To bump the shoulder back, just do not screw the die in as much. Start off a good bit away from the ram. See if it chambers. If not, screw the die in a little bit and try again until you get it to chamber how you want. Go slow, but this will work to bump the shoulders without having the get another die.
Redding also has some modified height shell holders that can be used to get a repeatable result for bumping the shoulder with your FL die. They may be worth a look.
If your FL die has an expander, take it out. To bump the shoulder back, just do not screw the die in as much. Start off a good bit away from the ram. See if it chambers. If not, screw the die in a little bit and try again until you get it to chamber how you want. Go slow, but this will work to bump the shoulders without having the get another die.
Redding also has some modified height shell holders that can be used to get a repeatable result for bumping the shoulder with your FL die. They may be worth a look.
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who makes the bump die?
Forster has a bushing bump die. Best way is to just use a FL die. Measure cases before sizing and then just slowly screw the FL die in until you're bumping back a thousanth or so.
I have used WW Grainger Arbor Shims to adjust quickly for bumping.
I have used WW Grainger Arbor Shims to adjust quickly for bumping.
I bump the shoulder 0.001. It's given me the best results, and you can do it with a FL Sizing die.
Agreed more on a semi as they tend to stretch the brass more but I am sticking with my .001 on a bolt.
For a gas gun redding small base dies are hard to beat, for a bolt go with the fl redding bushing dies
I used to use two separate dies for neck sizing and shoulder bumping. The problem with that is all brass does not act the same. In a given batch, you'll have some that grow at a greater rate than others, despite all other load conditions being the same. Nothing is more frustrating than running into that one long case. FL sizing is the only reasonable approach IMO, and it happens to be easier too. Win Win!
I strip my bolt down and test for closing force when setting up sizing dies. I then measure for future reference.
I strip my bolt down and test for closing force when setting up sizing dies. I then measure for future reference.
If you use a full length sizer die with a button/expander use lube on the inside of the neck or you could induce Run Out to the neck. Also if the lee die is not set up correctly it can cause problems at the major diameter of the shoulder.
