I need help with the following problem. I have a custom 17 Ack Hornet that is separating cases just forward of the web. Sometimes on the third firing sometimes on the sixth. The break is clean and no gas is escaping, the case is as clean as before firing.
I know it is a mild load so know that is not the problem. I measured cases from another 17 Ack Hornet and the length to the neck is 1.169 on the �old� cases and 1.189 on the custom case splitter. I am using Remington brass, which we all know is thinner and softer, but could the difference in the case length by making the case stretch too far to fill the chamber? My 17 HeBee is a lengthened case and doesn�t suffer the same problem. By the way, the last separated case grouped in .164 with two other rounds so I have to figure that everything is pretty square.
Any help or thoughts would be appreciated.
Thanks
Brooks

Your problem is typical of cases which are being over sized and the shoulder being set back too far. The cure is to set your die so that the shoulders are set back just enough to give easy chambering. That's about .001" setback when you full size. It's a die adjustment problem.

Hey Bob, I didn't mention that I am using a Wilson neck die exclusively so I am not pushing the shoulder back any, it fact there is a good amount of resistance when chambering.
Thanks
Brooks

BLH -- As you know, there aren't many all that many conditions that will cause your case to separate like that.

Excessive headspace is one of them. Excessive resizing is another. I am sure you know about both of them.

You might try this. With some new brass, fire-form it while headspacing on the bullet. This should keep the stretch in front of the web from forming and might increase your case life.

I looked in your post and could find no mention of the type of action. If it is an Anschutz or a M43 Winchester then that is part of the problem. They stretch. If it is a front locker or a Ruger #3 then that is not the problem. I have seen situations where somebody insisted that they couldn't be setting the shoulders back because they were using a neck die but they were in fact doing so. Double check to be sure. Case head separations are always an indication of headspace problems it is just the cause that varies. In the case of some of the rear lockers the headspace only exists as pressure peaks and the bolt compresses but it is headspace just the same. Regards, Bill.

Hey Bill, I am using a Wilson neck die but now do believe that when I drive the case in with a mallet it is pushing the shoulder back. Going to use a regular FL die backed off this weekend.
Thanks
Brooks

Here is what I found last night.
These are the measurements of the two guns.
Fired Cooper 1.160
The problem gun = Rampro
Fired Rampro 1.176
Fired & sized Rampro 1.174
So it appears that the sizing is not the problem.
Here is what I think is the problem.
Fire forming 1.167
I appears that in the fire forming process the bullet which is not touching the rifling is causing the problem. On a rimed case that shouldn�t make a difference but I believe that the striker is actually forcing the case forward at firing and the case is griping the chamber. The rear of the case then moves rearward. The primers are extremely flattened and given the shortened fire formed case on the subsequent firings the case if further stretching and then separating. I am going to try with the bullets jammed and see if this is actually the problem. What is sad is I am getting ff groups in the .4�s and some in the .1�s. Hope I can duplicate this with the bullets touching the lands.
Thanks for all the input, just needed to settle down and analyze.
Brooks