Shoulder Bump Range... What's Acceptable??

[L.Sherm]

I'm gonna disagree with you annealers milo is correct, I DON'T anneal my ADG 28 nos, 300wsm, 30-06 lapua brass and I get at most .0005 on 98% of the cases. Lube and keeping the fired brass sorted by times fired is the key.
Just measuring a fired case and adjusting your die to bump .002 isn't necessarily give you your bolt to close with no resistance either. The Wheeler method is the only way to measure bump for zero resistance. Eric Cortina has very good example of that on his new video about his die its worth a look, I believe he had to go to .004 for zero resistance on his comparator.

 

[L.Sherm]

It will set your brass to a constant and repeatable state

That is debatable, I know there's some BR shooters that are finding not annealing is better. Measure your NK I.D with a guage pin after annealing on all your brass I found alot of variance thats why I dont anymore. I found alot more consistently after I quit annealing, like Alex Wheeler always says though need to test for yourself.
The pause or dwell time at the bottom of the down stroke is good advice

 

[milo-2]

This is not necessarily true, as brass comes from several sources, presses and can/does have differences even within the same lot.
Heck, I've even seen headstamps within the same bags and boxes with small lettering and larger lettering, meaning they were formed on different presses…

Cheers.

One usually does not see this with modern quality brass. If buying Rem bulk, or Win orange bag, yes you probably will see what you are saying. I know exactly what you are saying, I bought some culled 6.5saum ADG brass from a member here, O.M.G is all I have.
3 firings were enough for the OP to see a uniform bump, the only thing pliable in his equation is the brass, and the only thing keeping his brass from going into the die equally is lube on the bottom half of the case.
His die was set for a .005" bump, some cases didn't go in far enough.

Off topic kind of, if you are going to anneal, do it every firing, establish a baseline and keep it. Though now you may actually encounter a slight seating force issue, only testing will figure out if you are still ok.
On the other hand, with brass springback from over worked cases, you may encounter a neck tension issue if you haven't annealed brass in 6-8 firings.
We all have to figure what works in that particular rifle.

 

[Philward]

Is there a sizing die that allows adjusting the shoulder bump independent of the body, where you don't have to screw the whole die in or out to achieve the desired bump? i.e. still have good cam over contact with the die for consistency and then a shoulder bump section to set the desired amount. I guess another set of threads would introduce more slop though and maybe some other issues.

 

[C-130 Dude]

That is debatable, I know there's some BR shooters that are finding not annealing is better. Measure your NK I.D with a guage pin after annealing on all your brass I found alot of variance thats why I dont anymore. I found alot more consistently after I quit annealing, like Alex Wheeler always says though need to test for yourself.
The pause or dwell time at the bottom of the down stroke is good advice

While I agree with you using a pin gauge for measuring inside neck, this guy is shooting mostly for field use. I suspect your inside neck variences are caused by variability in the brass manufacturing process. Thats why some turn their necks. BR is a whole other animal. BR shooters have their gear tolerances so tightly machined, they can process their brass differently. I suspect the op is not as concerned with going completely all the way to the bottom of the rabbit hole. Just a few steps will do. (As if that's possible)

 

[C-130 Dude]

Is there a sizing die that allows adjusting the shoulder bump independent of the body, where you don't have to screw the whole die in or out to achieve the desired bump? i.e. still have good cam over contact with the die for consistency and then a shoulder bump section to set the desired amount. I guess another set of threads would introduce more slop though and maybe some other issues.

Can't say as I have seen one. But maybe. If there was one my concern would be that as you push the case sholder back, without a supported body, the upper body would distort.

 

[VinceMule]

I'm gonna disagree with you annealers milo is correct, I DON'T anneal my ADG 28 nos, 300wsm, 30-06 lapua brass and I get at most .0005 on 98% of the cases. Lube and keeping the fired brass sorted by times fired is the key.
Just measuring a fired case and adjusting your die to bump .002 isn't necessarily give you your bolt to close with no resistance either. The Wheeler method is the only way to measure bump for zero resistance. Eric Cortina has very good example of that on his new video about his die its worth a look, I believe he had to go to .004 for zero resistance on his comparator.

I am in this camp.

There is always more than one way to skin a cat.

Various dimensions between brass manufacturers

Factory chambers

Production dies

custom barrels not cut to reamer spec

All are a can of worms

 

[VinceMule]

Is there a sizing die that allows adjusting the shoulder bump independent of the body, where you don't have to screw the whole die in or out to achieve the desired bump? i.e. still have good cam over contact with the die for consistency and then a shoulder bump section to set the desired amount. I guess another set of threads would introduce more slop though and maybe some other issues.

Standard Forster neck sizers can bump shoulders only, and this is not their bushing dies either.

Sizing the web only would be a "ring" die, too bad they are not being made at this time in graduated sets. I have cut the bottoms off of regular full-length sizers and small base sizers to use as ring dies, but there is usually some brass scraping involved from the body.

Some Redding body sizers with the die cut off to not contact the shoulder work, lathe and carbide tipped part off tool needed.

Some years ago, I chased the only bump back .002 on production guns, it was just easier to bump the shoulder back till the bolt closed easily on brass that needed full-length sizing, watch for case head separation lines in the brass, throw brass away as needed.

 

[nksmfamjp]

IME, annealing is all about fit and tolerance range.

Basically, a fired case should fit in the action and close the bolt with some run or drag of legs against the action. This, IMO, is due to action stiffness and case expansion/spring back. So about 0.0005" interference with primer removed. More with primer in.

Also measuring fired cases results in zero CBTD variation.

Then I anneal all brass.

Then I size a case until an disassembled bolt handle drops freely.

Then I size 10 to confirm my CBTD variation. In a bolt gun, I put this variation all into oversizing. Basically where no case is longer than bolt handle drop length.

On a T/C, I oversize another 0.001-0.002". These actions will partially lock up and misfire.

On AR's, I just sized fired minus 0.003".

In the end, this produces easy closing actions and generally good accuracy.

 

[birddog 68]

I've got a question for the more experienced than me.
280 AI hunting rifle and out of 50 pieces of brass I had about 7 pieces that bumped the shoulder back .005 instead of the .002 on all the others.
I kept these separate and surprisingly they actually shot better than the .002 bump brass.
Should I just bump them down .005 from now on since my rifle seems to prefer it?
Any safety or disadvantage in doing this?

 

[rm76]

The pause or dwell time at the bottom of the down stroke is good advice

I have not absolutely confirmed this, but since I have been pausing a couple or three seconds at the bottom of the down stroke while the case is in the top of the die, I seem to be getting less variation. However, I am also paying more attention to die cleaning and more lube consistency, and ofcourse annealing regularly.

 

[C-130 Dude]

IME, annealing is all about fit and tolerance range.

Basically, a fired case should fit in the action and close the bolt with some run or drag of legs against the action. This, IMO, is due to action stiffness and case expansion/spring back. So about 0.0005" interference with primer removed. More with primer in.

Also measuring fired cases results in zero CBTD variation.

Then I anneal all brass.

Then I size a case until an disassembled bolt handle drops freely.

Then I size 10 to confirm my CBTD variation. In a bolt gun, I put this variation all into oversizing. Basically where no case is longer than bolt handle drop length.

On a T/C, I oversize another 0.001-0.002". These actions will partially lock up and misfire.

On AR's, I just sized fired minus 0.003".

In the end, this produces easy closing actions and generally good accuracy.

Good points. The sizing processes I use are for MY guns. The bump I use is the result of measurements of MY bolt guns. I too bump .003 for my ARs'. Your milage will vary.

 

[C-130 Dude]

I have not absolutely confirmed this, but since I have been pausing a couple or three seconds at the bottom of the down stroke while the case is in the top of the die, I seem to be getting less variation. However, I am also paying more attention to die cleaning and more lube consistency, and ofcourse annealing regularly.

If it works, it works.

 

[azarcher10x]

Annealing is your friend on 300 RUM cases. It takes very few firings for the case to become hardened. I anneal, then use a small base die to bump the shoulder. If you're using an expander ball, be sure it's lubed with a good dry lube, so it doesn't pull the shoulder back out as it exits. (I prefer a graphite type, and I leave it inside the neck to prevent any bullet weld)