How much case stretch or shoulder movement is normal?

[onesonek]

" Maybe its just a sloppy mil-surplus action?"


Not the actions fault necessarily, but whom installed the barrel.
But it could be stretch of the reciever as well from hot loads over a period of time.
That mark ahead of the web is odd. A bit farther forward to be a incipient seperation ring.

 

[CatskillCrawler]

That mark ahead of the web is odd. A bit farther forward to be a incipient seperation ring.

That it is. Odd that is. :lol:

 

[Creedmore]

That mark ahead of the web is odd. A bit farther forward to be a incipient seperation ring.

That's where the separation happened. The same case from the other pictures I posted today, next to the separated case:

 

[300WSM]

"Just a reminder that if you are trying to full length re-size...anything......just kissing the shell holder is not enough. You have to turn the die 1/4 turn after the kiss so it cams over."

I'm sorry but I have to disagree with that. If I set up my dies in that manner, I'd be creating headspace problems in most of the rifles I own that that includes those with match grade chambers. I changed my methodof full length sizing when I learned that the belt on magnum brass wasn't worth a damn for headspacing and set up my dies to headspace on the shoulder. Now I set up all my dies to do this for bottleneck cartridges.

That wasn't the point. The point was based on the subject of full length re-sizing. I told him if he needed to FL size then just kissing the shell holder is not enough.

The issue was not based on whether to Fl size or only shoulder bump.

Pj your method would be just super if of course being used in the same rifle. I merely was telling him if he was Fl sizing that eventually only kissing the shell holder will not be not enough.

A majority of replies are not being very simplified here IMO. I repeat again, you don't have a normal feeling/acting chamber before the case sep...then you don't on one shot.

Chambers do not up and change like that.

 

[onesonek]

Ok, just a bit more forward than what I have seen before,,,,
Fireform your brass by either method mentioned earlier, and see what happens.
I also am not sure what that action is really up to. Might not want get too close to max .25-06 loads. Just sorata thinkin 48,000 cup might be plenty.

 

[Ridge_Runner]

ok, a sure fix, use 280 rem cases necked down, trimmed, and sized to just fit the chamber......problem solved.
RR

 

[Creedmore]

PJHunter has given you the correct method to set your FL dies commonly called Partial FL sizing. Gave up the normal instructions for cam over years ago when I seperated cases in two different rifles one a 300Win Mag and one a 308Win. It may be necessary in some cases but in none of the rifles I own or load for.Rick.

That's what (I think) I'm trying to acheive by using the bump gauge -- to set the resizer for a 0.002" bump.

My question -- how is partial FL resizing like this different from neck sizing? I have all 3 Forster dies: FL, Neck and Competition Seater. If the FL kiss + 1/4 turn works the case too much because of my chamber, then what do I gain from Partial FL resizing instead of just Neck Sizing?

Call me a sponge for knowledge. Keep it coming, and hose me down. :grin:

 

[Ridge_Runner]

first thing ya need to do is make a case fit your chamber, then use that die setting and it works like any other rifle to reload, an oversize chamber is not a big deal if ya know it and make your brass fit. I just can't help but wonder why it just showed up when ya changed powders. having a chamber .013 longer than min spec doesn't worry me at all, how and when it got like that is the kicker. making cases fit your chamber now will help, but what if what made it .013" longer continues and makes it .026" longer. have you always had short case life? have you ever loaded above min. pressures? thats the thing has it always been like this or do you have a soft action that is battering the lugs to cause excessive headspace?
RR

 

[Oldtrader3]

You need to check headspace in your rifle with a go/no go headspace gauge set first and determine if your rifle has correct headspace. Without checking headspace on that chamber, you do not know where you are starting out, headspace wise. Others have given you good instructions but without knowing actual headspace, you have no point of reference.

Assuming that it does have correct headspace, you need to set your full length sizing die to resize the case while only setting back your headspace shoulder datum by 0.0015/0.002. I use the 0.0015 setback number for all my full length sizing dies as a setpoint. My bolts close nicely on all on the cases which are set that way.

In order to do these measurements and setup, you need to have a RCBS Case Master Gauging Tool (or similar) type measurement fixture that you can actually read the headspace on a fired case and on a full length sized case at the datum point on the case shoulder or you do not know where you are dimensionally. Once you know where you are, you can start from there and measure unfired cases, fired cases and sized cases, then compare all three to the SAAMI specification for your rifle. Your present gauge setup does not seem to relate to the SAAMI specification for headspace and does not seem to tell you what you need to know?

I would not fire the rifle again until you get the headspace measured and your formed and fired cases measured at the headspace datum point by somebody competent. Just my $.02 worth.

 

[CatskillCrawler]

PJHunter has given you the correct method to set your FL dies commonly called Partial FL sizing. Gave up the normal instructions for cam over years ago when I seperated cases in two different rifles one a 300Win Mag and one a 308Win. It may be necessary in some cases but in none of the rifles I own or load for.Rick.

That's what (I think) I'm trying to acheive by using the bump gauge -- to set the resizer for a 0.002" bump.

My question -- how is partial FL resizing like this different from neck sizing? I have all 3 Forster dies: FL, Neck and Competition Seater. If the FL kiss + 1/4 turn works the case too much because of my chamber, then what do I gain from Partial FL resizing instead of just Neck Sizing?

Call me a sponge for knowledge. Keep it coming, and hose me down. :grin:

A neck sizer will only re-size your neck to provide adequate, consistent tension to retain the bullet. Because it doesn't push back on the shoulder, you can only do it so many times before the brass stretches far enough where it no longer has enough headspace to allow you to chamber a round and close your bolt.

Bumping the shoulders back .001-.002" by partially re-sizing using your full-lengh re-sizing die works the brass a little but not as much as full-length re-sizing your brass. The amount of "savings" is dependent on the amount of headspace your chamber has. A short chamber which only stretches your SAAMI sized brass .003", will only work your brass .003" if you full-length re-size. A long chamber with .011" headspace will stretch your brass more and you can benefit more from partial re-sizing. Keep in mind that your brass will stretch the whole length of your chamber and then rebound a smidgeon due to the elasticity of brass.

It makes more sense for a hunter to always partial re-size brass because it gives you a little leeway length-wise and always ensures that your brass will chamber in the field. A competition shooter may be more inclined to neck-size has brass only.

The less you "work" your brass, the more it retains its elasticity. Once the brass hardens (loses its elasticity) the more brittle it becomes and is more prone to splitting or cracking. To minimize the chance of incipient case failure, you try to minimize the amount of longitudinal stretching (from firing) and contracting (from re-sizing) you incur on the brass. To minimize neck splitting, you do work your neck every time you resize, be it full, partial or neck-sizing only, you need to anneal your brass after every 3-5 re-sizes. This returns the elasticity to the brass contrary to the effect heat has on iron-based metals.

I probably got twisted around in this but someone else will certainly correct any misunderstandings or errors I may have made here and get you to your Eureka! moment.

 

[Creedmore]

an oversize chamber is not a big deal if ya know it and make your brass fit. I just can't help but wonder why it just showed up when ya changed powders. having a chamber .013 longer than min spec doesn't worry me at all, how and when it got like that is the kicker.

It has likely been this way since day 1, I just never noticed. But since the separation, I started measuring and paying close attention. I used to just set the FL die to contacct the shellholder and move on, since sizing this way chambered just fine.

 

[Creedmore]

Just a followup. I made it back to the range today, and results were very good.

Since last weekend I cleaned the heck out of the chamber/lug areas in case there was still debris in there. Used a 20ga brush and some plastic pics with Kroil to try and reach all the lug areas as best I could. Swabbed/patched everything out good and hit it with the air compressor. Seems the bolt closes a little easier now, so maybe there was some brass debris in there still.

Next. I took the essentially fireformed brass from last weekend and only partially FL resized it, bumping the shoulder from 1.938 to 1.9355. I shot loads working up from 49.3 to 50.5gr H4831SC with a 110gr AccuBond, and didn't have any pressure signs or sticky bolts. The only other thing I changed was seating the bullets 0.010 deeper. The best group of the bunch was 0.5" with the 50gr H4831SC, at 3170fps.

I think the main problem was that I didn't realize the chamber was longer than normal. Sizing the brass so it didn't have much room to grow made a big difference. Now I know that I'll need to fireform my brass before doing any serious load development.

Thanks to everyone for the suggestions. Sometimes just helps to think it out with others.

 

[nvbroncrider]

Glad you figured it out.

 

[SJB358]

Glad you got it sorted out. Be interesting to see how much better your brass holds up as well.

Sounds like you have a killer load with H4831 and the 110AB.. That is a screamer!

 

[Con]

Be interesting to see how much better your brass holds up as well.

Longer then when the FL die was being screwed to the shell-holder. :lol: Nevertheless, the initial stretch has already thinned the brass so the damage is done and in waiting, that's why the poster that recommended you use 270Win brass or put a 0.264" expander through unfired 25-06 before fire-forming was correct. It prevents the initial stretch and thinning of the web.

Not sure about how you guys use the term, but 'Partial FL resizing' as I know it is using the FL resizing die to neck size only and not bump the shoulder. It's a technique fraught with its own potential problems. If the FL die is set to bump shoulders back 0.002" it in effect is operating as a FL resizing die and doing its intended work. With some dies that happens 1/8 turn past the point of shell-holder contact, others directly on shell-holder contact, I have one die set where it occurs 1/2 turn off the shell-holder. When the shoulder is bumped back 0.002" the solid web should also be reduced in size a poofteenth for easy chambering. When that doesn't occur, that's when we usually reach for the small base dies ... but in a 270Win you can achieve the same by using a 444Marlin FL resizing die. Reason I say 'usually reach for the small base dies' is that changing shell-holders can also have an effect on the amount of resizing.
Cheers...
Con

 

[rick smith]

Con, you can't neck size with a FL die. PFL is sizing the case just enough to fit your chamber, bumping the shoulder approx. 0.01-0.002, and not bringing the case back to original dimentions as in FL sizing. In this situation, FL sizing resulted in case head seperation. Most rifles do not require FL sizing to operate correctly.Rick.

 

[Oldtrader3]

There is only one method to fl size a case. Partial sizing of cases with a FL sizer until the case will seat in the chamber tells you nothing about the chamber or about the case dimensions to datum! You have to have a gauge which will measure the correct datum point on the case shoulder and put in in the correct place or you are quessing. Setting back a length case datum to about 0.0015 inches shorter than the chamber is the only way to properly headspace a case. Forget about where the end of the die ends up and forget about using partial turns of the die to set .001 inch settings, it won't happen! The die uses an -18 thread which is not precise enough to set headspace without a gauge.

 

[Creedmore]

Nevertheless, the initial stretch has already thinned the brass so the damage is done and in waiting, that's why the poster that recommended you use 270Win brass or put a 0.264" expander through unfired 25-06 before fire-forming was correct. It prevents the initial stretch and thinning of the web.

Con, ( and Ridge_Runner and onesonek ) . . .

I went back and re-read all of the comments about using a .264 expander and/or .270 brass. Still a bit confused on how this will alleviate the initial stretch. I'm intrigued, but can yall explain a bit more on the how-to and what it will do to the brass? not sure I follow. Thanks!

 

[SJB358]

Nevertheless, the initial stretch has already thinned the brass so the damage is done and in waiting, that's why the poster that recommended you use 270Win brass or put a 0.264" expander through unfired 25-06 before fire-forming was correct. It prevents the initial stretch and thinning of the web.

Con, ( and Ridge_Runner and onesonek ) . . .

I went back and re-read all of the comments about using a .264 expander and/or .270 brass. Still a bit confused on how this will alleviate the initial stretch. I'm intrigued, but can yall explain a bit more on the how-to and what it will do to the brass? not sure I follow. Thanks!

I think they meant you would be able to size a 280 case with the shoulder that is a little further forward than a 270/30-06. This would allow you to create a smaller secondary shoulder that would fit your chamber tightly and not allow the case to grow during fireforming. This would stop you from pulling brass from the rear of the case during firing to fill the front of your chamber.

Sorry for the crummy explanation, but I bet the others will have a more descriptive way of telling.

 

[Con]

Con, you can't neck size with a FL die. PFL is sizing the case just enough to fit your chamber, bumping the shoulder approx. 0.01-0.002, and not bringing the case back to original dimentions as in FL sizing. In this situation, FL sizing resulted in case head seperation. Most rifles do not require FL sizing to operate correctly.Rick.

Rick,
I see where your coming from now. Yes, 'FL resizing' is bringing the case back to minimum dimensions, but in this case where the shoulder is being bumped say 0.002" to fit this individual chamber ... in effect the case has been 'FL resized' for this particular chamber. FL resizing dies by the way will not return cases back to minimum spec, if they did we wouldn't have the need for 'small base dies'. Most FL resizing dies will work adequately to bump shoulders back to minimum spec, but they wont all resize the base itself to minimum specs.

Can a FL resizing die be used to neck size? Yes it can, its what we here in Australia call 'partial neck resizing' or 'partial full length resizing' ... usually described as the process of sooting the neck or marking it, then running the case into the FL die and seeing how much of the neck is resized, and turning the die down until the marks indicate the neck has been resized and the shoulder remains untouched. The issue with it can be that as the case sides get squeezed, the shoulder being unsupported can be pushed forward ... in my experience that usually happens with straight walled sharp shouldered cases ... but it really depends on the specs of the die itself. Its always worth remembering that there's no such thing as 'zero tolerance' machining and in reloading we're dealing with 3 machined components ... chamber, dies and brass. These are never perfectly matched so we have to make do with making them fit as perfectly as possible.

Creedmore,
You seem to have a chamber that is longer than it should be, per se that's not a problem with factory loads as long as they fire. As was mentioned, in a Rem700 type action those rounds may not fire. The M98 claw can hold cases back on the bolt face, its a nice design in that sense towards reliability. It's when your reloading the cases that issues can arise, in particular case head separations when the FL die is bumping shoulders all the way back to minimum spec because the die has been set to contact the shellholder or turned down a further 1/8 to 1/4 turn.

In your situation there are 3 methods that can be used to prevent rimless cases stretching down at the expansion point on initial firing, you want your shoulders to blow forward without stretching at the expansion point an excessive amount, in essence, you need to hold the case back tightly against the bolt face. 3 ways are:

1. Seat projectiles long so that they jam into the lands. By jamming in the lands it will hold the case head against the bolt face. Personally, this hasn't really worked for me, particularly where a heavy firing pin fall can still move the case forward.

2. Sticky tape cut in a thin strip (about 1mm wide) can be wrapped around the case head once so there's no overlap. It acts to 'thicken' the base and make it harder for the case to move forward when struck by the firing pin. Its fiddly but works.

3. Expanding case necks up one caliber is the easiest means that I've found. By expanding your 25-06 necks up to 0.264" you prevent them from chambering ... so you then use a FL resizing die or neck sizing die to slowly resize the neck back to 0.257cal checking whether the brass will chamber. When it just chambers with some feel of resistance on the closing of the bolt ... the job is done. The neck will now hold a projectile, but there'll be a 'bump' down at the neck shoulder junction which acts to hold the case in place.

All 3 of the above methods have a side benefit of keeping the case concentric in the chamber if the chamber itself is oversized.

Having done any of the above and fireformed your cases, you'll have brass 'custom fitted' to your long chamber. They'll still have stretched some at the point where case web meets case walls, but it'll be less than before. From that point on, if FL resizing you want the shoulder bumped back just enough to allow reliable feeding, not all the way back like if you set the FL die to come to a stop on the shell holder. Better yet, neck size only so the shoulder isn't bumped at all. You'll probably get 2-5 reloads before tight chambering tells you that the shoulder needs to be bumped back in the FL die that 0.002" amount to get easy chambering again.

Does that make it a bit clearer?
Cheers...
Con