Shoulder bump when FL resizing.

arlaunch

arlaunch

Active member
This last year i have been getting into larger calibers than
223 REM.

I have been working with Starline Brass in .308 and .270 Win as of late.

What i have noticed with the larger calibers is that some pieces will barely bump at all, and others will be way oversized.

I segregate all brass by number of firings, into lots and never mix. Even with 1 time fired brass i am getting large variations in shoulder bump.

Is this the brass, or is it just a common issue with larger calibers?

It is very frustrating to size one piece to find it did not bump the shoulder at all. Then have to run it through a second time. Then get another piece and it pushed the shoulder back .005 instead of .002 for a bolt rifle.

Each and every round needs to checked for headspace, then the die adjusted for the longest round to be set back .002-.003

Then half the cases are grossly over-sized...
 
Inconsistent lube will do what you're seeing. I don't know what press or dies you're using, but even with my Rockchucker there must be a little give, or stretch in the hardware, as the harder they resize, the less bump I get.
 
Shoulder only needs bumping when brass doesn't chamber properly(bolt effort). This is determined with the firing pin/spring removed from the bolt action guns. AR's when brass will not go into battery, I use a ammo checker for AR's or when ammo is used in multiple chambers. So for bolt guns with dedicated brass, bump from max length, hunting ammo is bumped to zero bolt close effort, bench ammo can have slight effort. Heavy bolt effort will gall the lugs on the bolt. Setup die gutted, and lube body and neck. So you set the die once, all brass is than sized. There will be no brass with a base to datum line that is long, but there can or will be brass that is not fully "formed".I use a mandrel for the inside neck diameter in a separate step. Let the brass stay in the die(ram all the way up, for 5-10 second "dwell" time, this will help with uniformity.
 
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I hope that I am not hijacking this thread, but I think that my question is related:

I have noticed that even with premium brass such as Lapua there is a variance of shoulder headspace that is as much of 6-8/1000 on NEW unfired brass (even after running them through my FL sizing die). How much does this difference in headspace affect group size? I would imagine that if I would take them out and fire them once they would all fire form to the chamber and then they would all be the same, but in the days we are living in, I don't want to use up primers and powder to do fire forming.

How much difference does a few 1000s variance on shoulder headspace make in group size?
 
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New factory brass/ammo will often be on the minimum(small or short) size of SAAMI cartridge specifications. It can take multiple firings for brass to fully form to an individual chamber. SAAMI chamber specifications are LARGER than cartridge specifications. The difference between the two does play a role in accuracy. Hunting ammo is typically "loose fitting" to enhance function and safety. Benchrest ammunition will be individual firearm fit and may not be possible to unchamber(intact, bullet will remain in barrel during extraction), but these will be the pinnacle of accuracy. As reloaders we most often work in the middle of these two, more accurate ammo with safe functioning ammo. Brass(bolt actions) with 0.0015-0.0025 headspace clearance generally functions well and will be more accurate than factory ammo, if all others factors(powder charge, bullet and primer) are the same. So minimize case fit,powder charge and bullet seating fluctuation is the way to more accurate ammo.
 
Ive always had trouble just bumping the shoulder a few thousandths. It did help when I started making sure to lube the cases good along with inside the neck. I also started annealing after every firing.
 
Easiest way to set your FL die is gutted(remove the decapping/expander rod). If after die body is set, and you install the rod the shoulder measurement changes(usually longer) means the expander is pulling too hard on the neck when lowering ram. Polishing the expander/properly lubing the inside of the neck will minimize the pulling and make shoulder sizing more consistent.
 
Originally Posted By: spotstalkshootEasiest way to set your FL die is gutted(remove the decapping/expander rod). If after die body is set, and you install the rod the shoulder measurement changes(usually longer) means the expander is pulling too hard on the neck when lowering ram. Polishing the expander/properly lubing the inside of the neck will minimize the pulling and make shoulder sizing more consistent.

^^^This. Slick expander and inside neck lube also reduce bullet runout. A floating carbide expander ball reduces friction as well.

Regards,
hm
 
I am very sensitive to smooth press operation. I am good at lubing necks because of this.

I am going to give this die soak/dwell time a try.

Using a mandrel to expand the case mouth has been on my do do list for about 5 years now. I should start the research into which sizes to try regardless.

Arky65,

Thanks for the EC video. I have seen that one before. Watched it again just for fun. I usually pull the expander out when doing die set up.
 
Erik has a good die setting instructions, I mark the die(black marker) so I measure from same location each time(as lock ring is adjusted). Notice that die set to touch shell holder was TOO MUCH SHOULDER SET BACK, Redding dies are at max sizing(brass will be minimum SAAMI) when touching their standard shell holder.
I put one 7.5 or 8 lead pellet under the die ring set screw, don't need to tighten the screw as much and will not rough up the die threads. Always make sure vent holes are clean(some dies have vents).
 
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Originally Posted By: arlaunch
I segregate all brass by number of firings, into lots and never mix. Even with 1 time fired brass i am getting large variations in shoulder bump.



I assume you are talking fire formed brass, not new? If it is fire formed to your chamber they should be relatively close to the same. If you are shooting different loads could be one is hotter than the other. Sometimes after multiple firings you'll find you need to bump back the shoulder because it wont chamber. Hard to compare once shot brass to brass that's been shot 5x. Some people are happy just F/L resizing everytime and make rounds that chamber and go boom. If you start trying to hold head space within +/-.001 you need to be more consistent in what you're doing. I'd F/L resize everything then load them all the same (not a light load) and shoot them. See if they're more consistent.
 
Tawnoper,

What you are referring to is brass spring back after it work hardens.

Segregating brass by number of firings, and adjusting the die down for brass that has multiple firings is fairly basic.

What do you mean by, i need to be more consistent with what i am doing?

I have had no problem nailing shoulder bump to within +/- .001 for years.

The difference now is loading different calibers with a different brand of brass.

I won't get a chance to tinker with this for another week or two. After another try i will post back my findings.

 
arlaunch,

Sorry, just trying to help out.

What I’m referring to is not spring back, different thing.

If you shoot multiple pcs of brass with different loads and different pressures you can get variance in how it conforms to your chamber.

Larger calibers afford more variance.

One thing is certain, reloading can be full of variables or pretty simple depending on your expectations.

Good luck with your issue.
 
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Sometimes I think we have too many gadgets to measure things. I set my die by pulling the decapping rod and expander and size till the bolt closes smoothly with no resistance. I use a Lee Turret press so the die stays that way. I FL size every tie and trim every time, in 60 yrs I've never had a casehead separation and my stuff shoots accurately. I've never measured shoulder bump. It doesn't seem like a very important measurement to me but then I'm not very anal about brass, never tumbled any and the only time I clean anything on the outside is when the neck starts to get black, I'll spin them and hold a green scrubby to the neck. I do clean primer pockets, brush the inside of necks and anneal when I start to feel variances in seating effort. When I build I do use the same headspace guage so all chambers are preyty much the same.

Suprisingly in all the years and all the different rifles I've owned and built I haven't yet had one that if the bore was reasonable looking to the eye wouldn't shoot to expectations, even had some that looked like a sewr pipe and would still kill a deer at 100 yards.
 
Well,

With regards to .308

After more experimenting on a new round of brass, after 2 firings, I have given up trying to size this Starline Brass.

After the 1st firing, many needed 2 or 3 passes through the sizing die to get the shoulder bumped back. Of course the variations in shoulder set back are someplace between extreme and wild!

After the 2nd firing, the brass is getting stuck up in the die, and pulling the shoulder out on the way down. The expander ball part is smooth as butter.

The hang up is coming down on the initial decent from the die.

I have been using Redding Imperial die wax on the outside and Lee case lube on the inside of the neck.

If i did not measure, i would have multiple cases that would not come close to chambering.

I am trying to weight my options. The die is a small base die.

New cases go through fine. The measurement below the shoulder, after sizing is - .0025. (does not seem too crazy)

I am not sure if this brand just needs annealed after every firing, or i need to get a regular FL sizing die?? Or both!!!???

Any ideas?

I have cleaned the die, cleaned the air hole, changed presses, many different types of lubes, cleaning with solvent in between.

Anybody else have multiple loads on larger Starline rifle brass?
 
243WSSM cases are the toughest I have run across and Imperial is over rated IMHO. The 243's scream like a banshee using IDW. Try some lanolin based case lube but clean your dies to remove all old lube first.
One Shot commercial or HOME BREW.

I also never found a need for small base dies, but avoided cases fired in full auto's. Shot tons of 7.62 range pickup off the rifle ranges using regular full length sizing dies in M1A and a .308 M1 and bolt guns over the years w/o issue.

Regards,
hm
 
I’m assuming this is in an AR. I had 2 barrels and have heard of others that didn’t like reloads. Some would stick in the chamber or not chamber. I shouldn’t say this but I took 1 piece of a 3 piece cleaning rod, put it in a drill with the swab end on with 100 grit emery cloth and seriously polished the chamber. Accuracy is great and my reloads don’t hang up. I know a guy that sold a gun because of this.
 
This evening i pulled out all my range pick up and sorted everything out. This is after giving up on trying to size Starline brass.

I ended up finding 26 cases of GGG, and 30 cases of LC Nato 2017-2021.

I ran all of them through and had not one problem. The GGG's averaged .002 variation and the LC NATO cases averaged around that also but had 2 or 3 outliers that made the variation .004.

They all came out of the die like they where bathed in hot butter!

I have been pulling my hair out with Starline brass. Normal for me is .013 variation in bump, with many being grossly oversized, while many need to be ran through the sizer die 2-3 times to chamber. It is nuts trying to set up a die in those conditions.

I suppose i have 2 options....

Anneal and see if that works
Return the brass.

I have a pile of it....


Do you guys think annealing will help??

I have nothing to lose on an existing lot. (except for several hundred dollars for an annealing machine) (And a bunch of studies on how to anneal)

The rest can go back to their maker.
 
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