Bumping back shoulder (.308) ?
- Thread starter thefitter
- Start date
Re: Bumping back shoulder (.308) ?
Do you full length resize or neck size?
If you full length resize every time, measure base to datum point on a fired case then set your die up so that the bolt will close with very little resistance and your done.
If you neck size only, let your chamber or a lock n load gauge tell you when to bump them back. You dont need alot of bump, just enough to close the bolt with a touch of resistance.
On the cartridges I neck size I have the base to shoulder datum point of a fired case written down. When I reach that measurement I bump them back .003 and drive on. Normally every third reloading.
Do you full length resize or neck size?
If you full length resize every time, measure base to datum point on a fired case then set your die up so that the bolt will close with very little resistance and your done.
If you neck size only, let your chamber or a lock n load gauge tell you when to bump them back. You dont need alot of bump, just enough to close the bolt with a touch of resistance.
On the cartridges I neck size I have the base to shoulder datum point of a fired case written down. When I reach that measurement I bump them back .003 and drive on. Normally every third reloading.
Re: Bumping back shoulder (.308) ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LR-WSM</div><div class="ubbcode-body">Do you full length resize or neck size?
If you full length resize every time, measure base to datum point on a fired case then set your die up so that the bolt will close with very little resistance and your done.
... </div></div>
I full length sized my first batch but I have discovered that my die was not really setting back the shoulder much if at all. Now on quite a few rounds there is some more than usual resistance when closing the bolt. Not sure if I can go ahead and use these rounds. I'm sure it's the shoulder and not the bullet so I should not be worried about pressure, right? Thanks
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LR-WSM</div><div class="ubbcode-body">Do you full length resize or neck size?
If you full length resize every time, measure base to datum point on a fired case then set your die up so that the bolt will close with very little resistance and your done.
... </div></div>
I full length sized my first batch but I have discovered that my die was not really setting back the shoulder much if at all. Now on quite a few rounds there is some more than usual resistance when closing the bolt. Not sure if I can go ahead and use these rounds. I'm sure it's the shoulder and not the bullet so I should not be worried about pressure, right? Thanks
Re: Bumping back shoulder (.308) ?
How did you have the die set up? Usually I set mine up where they are just making contact and then give it another quarter or so turn.
Maybe the die is doing it's job but you have an ever-so-slightly tight chamber? Turning the die just a little more should fix that.
How did you have the die set up? Usually I set mine up where they are just making contact and then give it another quarter or so turn.
Maybe the die is doing it's job but you have an ever-so-slightly tight chamber? Turning the die just a little more should fix that.
Re: Bumping back shoulder (.308) ?
A Lee collet neck sizer to decap and NS, then use a redding body die to resize the case and bump back the same amount every time. A 2 step process, but it works well for me.
A Lee collet neck sizer to decap and NS, then use a redding body die to resize the case and bump back the same amount every time. A 2 step process, but it works well for me.
Re: Bumping back shoulder (.308) ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LR-WSM</div><div class="ubbcode-body">Do you full length resize or neck size?
If you full length resize every time, measure base to datum point on a fired case then set your die up so that the bolt will close with very little resistance and your done.
... </div></div>
I full length sized my first batch but I have discovered that my die was not really setting back the shoulder much if at all. Now on quite a few rounds there is some more than usual resistance when closing the bolt. Not sure if I can go ahead and use these rounds. I'm sure it's the shoulder and not the bullet so I should not be worried about pressure, right? Thanks </div></div>
Measure a fired case as advised above then set your die up to bump the shoulder dimention back .002 you should feel a cam over at the bottom of your press stroke.
Also make sure that you keep your necks trimmed under 2.015 as a long neck will also give you the bolt resistance as its trying to advance into the throat area. This can cause a very bad overpressure issue causing a ruptured case or worse. If you dont want to invest in the tools, just keep test fitting the empty cartridge in your rifle and resize untill the bolt closes and lock your die down at that setting.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LR-WSM</div><div class="ubbcode-body">Do you full length resize or neck size?
If you full length resize every time, measure base to datum point on a fired case then set your die up so that the bolt will close with very little resistance and your done.
... </div></div>
I full length sized my first batch but I have discovered that my die was not really setting back the shoulder much if at all. Now on quite a few rounds there is some more than usual resistance when closing the bolt. Not sure if I can go ahead and use these rounds. I'm sure it's the shoulder and not the bullet so I should not be worried about pressure, right? Thanks </div></div>
Measure a fired case as advised above then set your die up to bump the shoulder dimention back .002 you should feel a cam over at the bottom of your press stroke.
Also make sure that you keep your necks trimmed under 2.015 as a long neck will also give you the bolt resistance as its trying to advance into the throat area. This can cause a very bad overpressure issue causing a ruptured case or worse. If you dont want to invest in the tools, just keep test fitting the empty cartridge in your rifle and resize untill the bolt closes and lock your die down at that setting.
Re: Bumping back shoulder (.308) ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body">
How often do you bump your shoulder back? Only when the bolt is tight to close? How tight is too tight? Every re load? Thanks </div></div>
I bump the sholder back when it measures out of spec. I use an RCBS case micrometer and have a known mark on the dial for my particular chamber. You can also use a Hornady (n.e. Stoney Point) attachment.
If you can feel the bolt closing AND this is harder than just the pressure friction of the ejector pin, then the case should have had its sholder bumped.
Measure every time, bump sholder when necessary.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body">
How often do you bump your shoulder back? Only when the bolt is tight to close? How tight is too tight? Every re load? Thanks </div></div>
I bump the sholder back when it measures out of spec. I use an RCBS case micrometer and have a known mark on the dial for my particular chamber. You can also use a Hornady (n.e. Stoney Point) attachment.
If you can feel the bolt closing AND this is harder than just the pressure friction of the ejector pin, then the case should have had its sholder bumped.
Measure every time, bump sholder when necessary.
Re: Bumping back shoulder (.308) ?
If you can close the bolt on them they are fine to shoot. That's self-limiting because if you can't close the bolt the firing pin can't hit the primer.
Fitter, this is a "precision" activity but it's not reducable to mathmatic foumulas. WE decide whan it's more effort than we wish to chamber a cartridge and WE need to experiment to learn what our rig prefers. It has been determined that some rigs shoot best if the shoulders are set back a couple thou each time, some do better with just a touch of resistance in closing and some (not many) do best with a firm fit and tight closing. Therefore, no one can tell anyone else what their rig will do best with.
If you can close the bolt on them they are fine to shoot. That's self-limiting because if you can't close the bolt the firing pin can't hit the primer.
Fitter, this is a "precision" activity but it's not reducable to mathmatic foumulas. WE decide whan it's more effort than we wish to chamber a cartridge and WE need to experiment to learn what our rig prefers. It has been determined that some rigs shoot best if the shoulders are set back a couple thou each time, some do better with just a touch of resistance in closing and some (not many) do best with a firm fit and tight closing. Therefore, no one can tell anyone else what their rig will do best with.
Re: Bumping back shoulder (.308) ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">If you can close the bolt on them they are fine to shoot. That's self-limiting because if you can't close the bolt the firing pin can't hit the primer.
Fitter, this is a "precision" activity but it's not reducable to mathmatic foumulas. WE decide whan it's more effort than we wish to chamber a cartridge and WE need to experiment to learn what our rig prefers. It has been determined that some rigs shoot best if the shoulders are set back a couple thou each time, some do better with just a touch of resistance in closing and some (not many) do best with a firm fit and tight closing. Therefore, no one can tell anyone else what their rig will do best with. </div></div>
Thank you! That's exactly what I need to hear. I'm going to shoot these and see how it goes.
I loaded 3 groups for ladders using 155, 168 and 175. I did not want to have to go and pull them all and hand measure again.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">If you can close the bolt on them they are fine to shoot. That's self-limiting because if you can't close the bolt the firing pin can't hit the primer.
Fitter, this is a "precision" activity but it's not reducable to mathmatic foumulas. WE decide whan it's more effort than we wish to chamber a cartridge and WE need to experiment to learn what our rig prefers. It has been determined that some rigs shoot best if the shoulders are set back a couple thou each time, some do better with just a touch of resistance in closing and some (not many) do best with a firm fit and tight closing. Therefore, no one can tell anyone else what their rig will do best with. </div></div>
Thank you! That's exactly what I need to hear. I'm going to shoot these and see how it goes.
I loaded 3 groups for ladders using 155, 168 and 175. I did not want to have to go and pull them all and hand measure again.
