5th reload bump shoulder why?

[MHouser]

I thought that by fire forming brass you were producing brass that was basically the same size as your chamber minus a thou or so because the brass springs back a little.

You could then simply keep neck sizing from that point forward.

If so, why after 4 or 5 firings do I need to bump the shoulder?

I would have thought that I would either have to bump the shoulder every time or never, not once in a while.

I ask this because I was planning on purchasing a Hornady headspace gauge (the one that attaches to your caliper) and thought... how would I use the gauge to measure my rifles headspace even if I had one? Would I measure once fired brass or brass that has been fired 4 or 5 times or what?

 

[warrenb]

After a certain amount of firings you will find they get harder to chamber and some/most may not chamber. Banging open your bolt on the ones that won't chamber, possibly every few rounds, is a pain at best.

At that point I full size again.

EDIT: If you shoot a savage you can set your own headspace to match the brass from your full size die.

 

[mmattockx]

After a certain amount of firings you will find they get harder to chamber and some/most may not chamber.

+1. Every rifle/cartridge is different, and generally, the higher the pressures you are running, the more this can be an issue. My .338 Win Mag needs the shoulders bumped about every 4 firings, while my 6.5x55 doesn't even seem to ever need the brass trimmed, let alone shoulders bumped.

I don't own any, but I have heard that the WSM's are bad for the shoulder moving up. As always, YMMV.

Mark

 

[Ganderite]

Bump when the gun says it is time to bump. I shoot a 260 Rem Ackley and have yet to bump. Waiting for the gun to give the word.

 

[m39a2]

Each time you fire, brass flows, whether neck sized or full length. Try trimming your brass after each firing, this will tell you if you are getting brass flowing enough to cause your problem.

Scott

 

[MHouser]

Each time you fire, brass flows, whether neck sized or full length. Try trimming your brass after each firing, this will tell you if you are getting brass flowing enough to cause your problem.

Scott

I do trim each time and was seeing minimal trimming required. Anywhere from 0 - 1 thou.

So to answer the last part of my original question I guess I would measure the brass that was just starting to show signs of being difficult to chamber to determine the hadspace (in this rifle)?

I realize it would be different for different guns but what would the approx diff in measurement be between the once fired brass above and brass fired 4 or 5 times? Would it be like 1 thou or more than that?

 

[cycbb486]

That is why we who shoot Shortrange BR always full length and neck size at the same time every time in our 6PPC's. We use dies that are so close a fit to our chambers that the brass is maybe worked approx 2 thou ALL around. At the same time we size the necks to the tension we want according to our bushing of choice. We use our brass maybe 20 pieces over and over again till we feel it is time to pitch it or the primer pockets get to loose. Those pieces can be reloaded as much as 40+ times before being pitched. I pitch mine on the spur of the moment. If I get P++++d off and shoot a bad group it may go in the garbage or may not.

So many misunderstandings on neck sizing.............

I think one will find if they prep there brass more like the BR shooters they would find less issues with it in the long run.

My take on this.

CBY

 

[MHouser]

That is why we who shoot Shortrange BR always full length and neck size at the same time every time in our 6PPC's. We use dies that are so close a fit to our chambers that the brass is maybe worked approx 2 thou ALL around. At the same time we size the necks to the tension we want according to our bushing of choice. We use our brass maybe 20 pieces over and over again till we feel it is time to pitch it or the primer pockets get to loose. Those pieces can be reloaded as much as 40+ times before being pitched. I pitch mine on the spur of the moment. If I get P++++d off and shoot a bad group it may go in the garbage or may not.

So many misunderstandings on neck sizing.............

I think one will find if they prep there brass more like the BR shooters they would find less issues with it in the long run.

My take on this.

CBY

Thanks and understood. Been doing a ton of reading but don't have a ton of practical experience. Would like to compete in 1000 yard f/tr. Building up the knowledge, equipment and experience to do so. Kind of in that order.

How far do you bump the shoulder back from max (I.e. Tough to chamber length)? 2 thou? And do you remove the expander ball from your full length sizing die?

 

[bigedp51]

MHouser

As stated below competitive shooters use custom dies that full length resize their cases to .001 to .002 smaller than actual chamber size. There are basically two reasons for this.

1. They do not want to put excessive pressure on the locking lugs and take a chance of galling the lugs after they were lapped for equal contact. They will also lube the locking lugs every 20 to 30 rounds with a good grease.

2. Better accuracy is achieved by "minimal" full length resizing, if the case sidewalls are not a uniform thickness, unequal case expansion will occur and cause case misalignment with the bore. You will also see the pros use Finish made Lapua cartridge cases because of quality control and case uniformity.

With standard commercial chambers you can use a standard full length resizing die and only partially resize the case to minimally size the case side walls and a bump die to push the shoulder back as needed.

NOTE: More "inaccurate" ammunition is hand loaded because of expander ball misalignment than "any" other cause. And this is why the Lee Collet die is so popular because the mandrel is "floating" and self aligning and thus less bullet runout.

Neck sizing only promotes longer case life "BUT" it is not always the most accurate. Remember all it takes is for one side of the case to be .001 thinner on one side and the cartridge case when fired will be out of alignment. On some cases with greater case wall variations you can end up with a severely warped "banana" shaped case after firing that can "never" be realigned and straightened by full length resizing.

At http//www.accurateshooter.com/ I was surprised to see that Winchester brass was second runner up to Lapua brass if you wanted to save money. (better quality control than any other American made brand of cartridge case) I always liked Remington brass "BUT" their quality of late has not been very good.

Some "toys" that make life easy resizing cases to a perfect fit to "your" chamber.............

"How far do you bump the shoulder back from max (I.e. Tough to chamber length)? 2 thou? And do you remove the expander ball from your full length sizing die?"

Between .001 and .002 for bumping the shoulder back and that is what the "toys" are for above.

To make the expander ball self aligning a small rubber o-ring is placed under the lock nut and only made "lightly" finger tight. The decaping pin should move freely from side to side with light finger pressure. The rubber o-ring ensures the expander ball "floats" and is self aligning for zero case runout.

 

[cycbb486]

Thanks Biged for your input (details) on this subject. Maximum case life can be found sizing brass in the manners mentioned above.

When I set my dies for sizing, (will use my 6PPC's for example) I remove the firing pin assembly from my bolt so I do not feel that cocking resistance. Idealy the ejector should be removed as well from the bolt. Take a fired case and try and chamber it. The bolt may or may not close with LITTLE resistance. With my custom action rifles when the bolt is stripped and no case in the chamber the bolt will fall closed under its own weight. Brass sized to give max life and performance will be sized JUST enough so you feel slight resistance when the bolt is closed.

Basically you start with your die out and slowly work it in until you feel the bolt close with the slightest resistance. A comparator works great for knowing what your fired brass length is at the Datum and helps you get to that approx 1-2 thou shoulder set back. I will set my die up so that it will oversize the case slightly and lock the ring on the die. Then I will throw shims in so the case will not be sized enough. Size a case and see how the bolt closes. Not enough remove a couple thou of shim, size and try again till I get exactly the feel I want.

When all is said and done mark the shim amount in your loading book for that rifle and die.

As Ed has shown, some of the toys above are GREAT assets to the reloader. My favorite is Skips Shims. Order 3-4 sets of these and you are set. You will never have to many. The shell holders work as well but you pay a lot more for them to get the range of adjustment with the shims.

CBY

 

[bigedp51]

The more gauges you get the more fanatical you become about your brass. You would be amazed at the variations in case wall thickness from one side of the case to the other and this also can cause case/bullet misalignment with the axis of the bore. (And why the pros full length resize their cases)

 

[H4831]

The cart sort of got ahead of the horse on this thread. Rifles are headspaced to a standard. Ammunition is made to fit within the limits of this standard.
What the OP started out talking about was his ammunition in his rifle. No need for him to measure the chamber length of his rifle, all he (anyone) is concerned with is how his ammunition fits his rifle.
The usual way to do this is to use cases fired in that rifle only and, as most people say, just neck size them. However, as the OP found out, after a few firings, and five is a common number, the cases have stretched enough that they will not go comfortably into the chamber, so the shoulder must be bumped back a bit. A far better way of doing this is to set the sizing die to just barely touch the shoulder of the case. Thus, you are not pushing the shoulder back on sizing, you are only preventing the shoulder from "growing." This way you always are using cases that are a perfect fit in that chamber.
Now, lets suppose you just got a whale of a good buy on a rifle, because the gunsmith said the headspace was beyond the standard length. In other words, the gauge that is not supposed to chamber, will chamber in this rifle. Firing new ammunition in this rifle will so stretch the case, just above the web, so that (1) the case will be ruined for further use, or (2) the entire case may seperate at this point on first firing. In either case you will not have once fired brass suitable for your rifle for reloading.
All is not lost, here is what you can do. Buy new brass, or, pull the bullets from factory loads and dump out the powder. With a primed case, load a light load of faster powder. A good source of finding what a light load is, will be a book such as Lyman's handbook of cast bullets. Cast bullets work well and are cheaper, but jacketed ones will do. Seat the bullet so it pushes hard into the lands on closing the bolt and in a suitable area, such as your range, fire the cartridge. The undamaged brass that comes out will be a perfect fit in your rifle with the excess headspace.
Now, set your sizing die to just kiss the shoulder, as described above, and you will have a perfect fitting combination of case and chamber fit.
In other words, headspace just refers to certain ammunition used in a particular chamber.

 

[cycbb486]

Just one other thing to waht 4831 said, make sure you lube the case well before you chamber and fire it the first time. If you do what was said above the brass should move in the shoulder area and not the web.

 

[Ron AKA]

Your gun will tell you when you need to bump the shoulder. With standard dies there are a couple of ways to neck size. One with the neck die, but not size the full length of the neck. This leaves 1/3 of the neck to fit your actual neck in the chamber tighter, and potentially improving concentricity. You can do the same with a FL die, but just set it to short stroke so only 2/3 of the neck is sized.

When you do bump most try for 0.001", and with standard dies you need a gauge to do that. On my Forster bushing bump die, I just remove the neck bushing and drop the cartridge into the die, and measure the overall length. I then size the cartridge until it is 0.001" shorter. I can get away with this because the Forster die does not contact the body, only the shoulder. I actually use this setting for each sizing and bump 0.001" each time, while still only sizing 2/3 of the neck. You have this control with a bushing/bump die, but not with a standard neck die or FL die.

 

[bigedp51]

Just one other thing to waht 4831 said, make sure you lube the case well before you chamber and fire it the first time. If you do what was said above the brass should move in the shoulder area and not the web.

The British military in 1929 said "DON'T" lube your ammo.

The American military in 2008 said "DON'T" lube your ammo.

The reloading manuals tell you to "NOT" lube your ammo.

And the firearms manufactures tell you to "NOT" lube your ammo.

The effects of oiled cartridges and excess bolt thrust.
Mauser type bolt action.

M16-A4 bolt cracked and lugs sheared from bolt thrust.

Any questions?

 

[H4831]

None of us would lube the ammo on full power loads. I think we are all well aware of what took several pages of diagrams to "inform us."
In the issue at hand we are talking about light loads, which in no way would harm the rifle.
It may not be completely neccessary to lube the case, but a light lubing would surely produce good brass.

 

[bigedp51]

H4831

No one in this posting said anything about measuring chamber headspace other than you. The RCBS Precision Mic is made for measuring cartridge case length and the shims and shell holders are for resizing the cases to .001 to .002 undersized of chamber length.
(bumping the shoulder back)

Seating your bullets long and hard into the rifling will hold the case against the bolt face or creating a false shoulder "WITHOUT" oiling or lubing the cartridge cases and doubling the bolt thrust on the rifle. To this day the British miitary still use oiled proof cartridges to test their small arms and on the Enfield rifle it was also used to "seat" the locking lugs and bolt head because it exerts twice the thrust on the bolt as a dry cartridge does.

The cart did not get ahead of the horse on this thread, what is need is more careful reading of what is written by people other than yourself and what they posted.

All the people who advocate lubing or oiling cartridge cases do not have the pressure measuring equipment necessary to even back up their claims when the firearms industry does and they tell you to "NOT" lube your cases.

 

[H4831]

H4831

No one in this posting said anything about measuring chamber headspace other than you. The RCBS Precision Mic is made for measuring cartridge case length and the shims and shell holders are for resizing the cases to .001 to .002 undersized of chamber length.
(bumping the shoulder back)

Seating your bullets long and hard into the rifling will hold the case against the bolt face or creating a false shoulder "WITHOUT" oiling or lubing the cartridge cases and doubling the bolt thrust on the rifle. To this day the British miitary still use oiled proof cartridges to test their small arms and on the Enfield rifle it was also used to "seat" the locking lugs and bolt head because it exerts twice the thrust on the bolt as a dry cartridge does.

The cart did not get ahead of the horse on this thread, what is need is more careful reading of what is written by people other than yourself and what they posted.

All the people who advocate lubing or oiling cartridge cases do not have the pressure measuring equipment necessary to even back up their claims when the firearms industry does and they tell you to "NOT" lube your cases.

I thought I did read pretty carefully. After all, this is what the original poster said about measuring headspace:

"I ask this because I was planning on purchasing a Hornady headspace gauge (the one that attaches to your caliper) and thought... how would I use the gauge to measure my rifles headspace even if I had one? Would I measure once fired brass or brass that has been fired 4 or 5 times or what?"

 

[bigedp51]

H4831

Hornady doesn't make "headspace" gauges to check chamber headspace.

But they do make gages to measure "cartridge headspace" or length, which is a variation of the RCBS Precision Mic for measuring cartridge length.

Hornady Lock-N-Load Headspace Gauge Bushing Kit. (Hornady bought out Stony Point precision gages)

Includes five interchangeable bushings (A-E) that attach to your caliper using the same B-2000 body as found on the Bullet Comparator. These five bushings provide the ability to check most bottleneck cases, from .17 Rem. through the belted magnums. Ackley Improved chambers use the same bushing size as the parent case.

Cartridge Headspace, rear of case to the datum line.

Sorry H4831, its one of them newfangled gadgets and all you old timers did was smoke the case and check for the same thing.

"The only difference between men and boys is the cost of their toys"

 

[MHouser]

H4831

Hornady doesn't make "headspace" gauges to check chamber headspace.

But they do make gages to measure "cartridge headspace" or length, which is a variation of the RCBS Precision Mic for measuring cartridge length.

Hornady Lock-N-Load Headspace Gauge Bushing Kit. (Hornady bought out Stony Point precision gages)

Includes five interchangeable bushings (A-E) that attach to your caliper using the same B-2000 body as found on the Bullet Comparator. These five bushings provide the ability to check most bottleneck cases, from .17 Rem. through the belted magnums. Ackley Improved chambers use the same bushing size as the parent case.

Ya, I know what the gauge measures, who makes it and what you get if you buy the kit. My question was about actually using it and whether I should be measuring once fired brass or brass after it has been fired 4 or 5 times (i.e. when it starts to become tough to chamber).

I do enjoy all the pictures though.

Anyway, I think I get it now. Cycbb486's comment below pretty much answered my question. When you say comparator you are talking about the Hornady Lock-N-Load Headspace Gauge or similar tool right.

Basically you start with your die out and slowly work it in until you feel the bolt close with the slightest resistance. A comparator works great for knowing what your fired brass length is at the Datum and helps you get to that approx 1-2 thou shoulder set back.