sure enough, shoulder moves forward.....

[Boyd Allen]

Joe,
Thanks for bringing this up. I have a second 6PPC that is also a .262 neck (but the chamber was not cut with my reamer). When I first worked up a load for it, I thought that I could use my gizzy. Luckily I caught the problem. The unsized portion of the neck is just slightly larger than the one cut with my reamer, giving a false reading. Fortunately I have a couple of those brass shoulder gauges that Lynwood Harrell furnishes with his dies, and these have a large enough hole to accommodate any neck diameter. Since this tool works with both of my rifles, I will probably stop using my gizzy for setting up my FL die. I will also have to look at what the differences are in headspace, as soon as I have fired some cases enough times so that the shoulder to head length has reached its maximum. Luckily, I can change the insert in my Vari-base die, so that I won't over size the slightly larger bottom of body diameter of my newest PPC.

For those of you that have written about case head separations that happen after only a few firings, this can be caused by a die that is too big for the chamber in combination with setting the die by feel. The shooter keeps screwing the die down until he gets the bolt close feel that he is looking for, and because the die is too large compared to the chamber the shoulder is pushed back too far, which leads to separation at the head. Telling someone to set a die by feel, when you don't know that relative sizes of the his rifle's chamber and his FL die is really bad advice that is very common on the internet. Also I find it somewhat curious that some so strongly resist buying and using one of the very inexpensive tools that clamp onto a caliper, and are designed to measure shoulder bump. In short, stop working by feel, and measure, with the correct tool.

Added a few minutes later:
If a caliber has a rather small shoulder angle, it may be best to set up your FL die so that the case shoulder to head measurement is the same as the fired case. I found this to be the case with my .220 Swift. The die would size the body diameter significantly, and so the bolt feel was just fine with the shoulder located as it was after firing. with any bump (measured) a bright line that indicated some thinning at the head, would appear very early on. With the modified procedure, the problem went away.

Smaller shoulder angles allow cases to be more easily driven forward into the chamber by a heavy firing pin fall and the force of the primer. By not bumping the shoulder I was limiting the "run" at the chamber shoulder which limited how far the case was driven. Anything that produces an excessive gap between the bolt face and case head, even if it is during firing, will lead to early separation.

I remember fellows in the back room of a local gun shop sagely observing that the reason that their belted magnum cases had such short lives was the higher pressure that those calibers were loaded to. The truth was that in those days, they did not have a clue that they should have been checking how far cases shoulders were being pushed back when FL dies were set to touch shell holders. Because there is no standard for head to shoulder in a belted case, the shoulder setback from such sizing can be extreme.

When I have measured how far shoulders of belted cases were blown forward during the first firing of new cases, it ran about ,021". Imagine a die that returned the shoulder to a point even half that far back from the chamber length. That is why their cases were only good for three firings, not the pressure.
Boyd

 

[Boyd Allen]

Mikecr,
By being focused on brass life and chamber fit, one can forget that the more important (to me) fit is down at the other end of the range. For me, and many others, nothing is better, unless it is better down there. Records are being broken quite regularly in short range benchrest. Tomorrow you will probably see an account (hopefully with pictures) of what is very likely a new 100 yard five shot unlimited potential record, shot Saturday at Visalia. I would bet money that Rick Graham's group was shot with some "ill fitting" FL sized cases. As a matter of fact, I am pretty sure that most of the records that are currently on the books were shot by shooters that chose to so handicap themselves. Close fit is only an advantage if it produces superior results. Lately, in short range benchrest, it has not.

 

[Al Nyhus]

But then, there is also nothing good in sizing the full length of necks.

Mike, sizing the full length of the case neck can be quite beneficial in some BR combos. -Al

 

[Butch Lambert]

Joe Salt and others need to make sure the primer is out before reading your gizzy. You can do that without any sizing.
Butch

 

[mike in co]

It's often been postulated that when setting up the resizing die if you set the die just high enough to not touch the shoulder, f'rinstance the guys who want to "neck size only" using a FL die, that the shoulder actually bulges FORWARD until you get down far enough to reset it.


al

al...
if one is neck sizing only, one does not tocuh/resize any of the case body, no the shoulder does not move forward.( as in a neck bushing die...or a fl die where the die is turned up enough to NOT resize any of the body.)

any other case where the die touches the case body..the brass has to go somewhere..and that somewhere is up since the case is surrounded by the steel die.

mike in co

it does

 

[DaveT]

Also I find it somewhat curious that some so strongly resist buying and using one of the very inexpensive tools that clamp onto a caliper, and are designed to measure shoulder bump. In short, stop working by feel, and measure, with the correct tool.

Boyd or anyone else,
Then you all give me your amount of shoulder bump, .001, .002 etc, hope I got the . in the right place. Yes Boyd you are correct sir, I should have purchased a shoulder bump gauge before this, I have done this for over 30 years going by feel and just recently have had head seperation on my 22-250. By the way, I just ordered shoulder bump tools from Sinclair. Great thread folks, keep this coming....
Dave T

 

[4Mesh]

I have been reading this thread with interest. I have an older 700 BDL Remington Varminter in 22-250. When I try to full length resize my cases, it seems the further down I screw the die the tighter the shells seem to fit the chamber? I'm not a novice here, I have changed full length dies 3 times trying to fix this problem, currently using Redding Type S bushing die. I have many bolt action rifles and have no problem setting up a die to match the chamber. I seem to have to screw my die down really far and can feel a lot of push when I size a case to get the cases to chamber half decent, but the last time at the range I had splitting above case head, real bummer so I know that means shoulder pushed back too far. Should I get a custom die made for this gun?
Dave T

What may be affecting Dave here, and what I am surprised nobody else mentioned, is that the more you size a case, the longer it grows. Using a chamber length gage and trimming length is as important, or more so, than getting the case to fit the diameters.

Often on the internet, you'll see guys talk about case growth when firing high pressure loads. In truth, the growth more often takes place on the loading bench.

Another thing that has not been mentioned here, is dealing with pressure when firing larger cases. The amount of pressure inside a chamber is not only quantified in PSI, it is also done by adding up the "SI's". Something like a 300WSM has a nominal case size (Sammi Spec) of .5586 at the base to .5386 at the shoulder. Meaning, the outer circumference at its smallest point on the body is 1.69". If I figure .030/side body brass, the inner circumference is on the lines of just over 1.5".

Several statements above in this thread are more true when applied to smaller cases, say, a PPC, 223, Swift, 22-250, or others. The largest of those, a 22-250, isn't a patch on the size of a wsm. Will it grown under equal pressure the way a WSM does? Not hardly. Can you neck size only on a WSM? Not often at competitive pressures, no.

 

[Boyd Allen]

The tricky part about shoulder bump is that it can vary at the same die setting within a batch of cases that came out of the same box and have been fired the same number of times. If you set up your die to bump one of the harder cases say .001 it may bump a softer one quite a bit more. On the other hand, if you happen to grab one of the softer ones, you may get no bump at all with a harder one. Hard and easy bolt closure, within the same group will open it up.

Using a shell holder that toggles the press a little, applying a uniform amount of lube, having the same top of ram stroke dwell time, and firing each set of cases in rotation, so that the number of firings per case stays uniform, all help uniformity. Beyond that you get into annealing, for which you need Ken Lights treatise, and disregard all the guys who write of even slightly glowing cases, dark room or not. I set my die to bump my 6PPC cases .001. When I am helping someone load for a game hunting trip, I pull the striker assembly out of the bolt, and check every case to be sure that the bolt closes the way that I want it to, this after setting up the die, properly with a gauge. BTW when a friend bought an annealing machine his bump variance problem went away. Another friend has used a more labor intensive system to do the same thing for all of his varmint cases, and he reports very even bullet seating force, and excellent accuracy, the last time he checked the zero on a couple of rifles that had been put away for the off season.