Is it incipient case head separation or something else.

[X-man]

I've seen new reloaders do this before. It's not necessary to full length resize your brass if you're using the same rifle. If you do, you will quickly overwork the brass, make it brittle and have it crack on you. Your initial firing fireformed the brass to the Mohawk's chamber, all that is required is a light resizing of the neck. If you have more than one rifle in this caliber, either buy a different make of brass or start marking the brass so you'll know what brass belongs to what rifle. I think the new neck size die will solve your problem. Best of luck!

 

[bigedp51]

Is there a way to do this without the gauge. Can my friend use a once fired case from his gun?

Yes you can do this the old fashioned way, place a .010 feeler gauge on the top of the shell holder and screw the die down until it contacts the feeler gauge. Then tighten the die and size a case and see if the bolt will close with no resistance. If resistance if felt then use a .008, .006 .004 feeler gauge in progressive steps until the bolt closes normally with little to no resistance.

 

[bigedp51]

Just got a neck sizing die.

The problem with a neck sizing dies is the case shoulder will need to be bumped back when the case becomes hard to chamber. I'm a fan of full length resizing and the case fitting the chamber like a rat turd in a violin case.

Please notice below that Kevin Thomas worked in the Sierra ballistic test lab and now shoots for Team Lapua USA.

 

[liberty]

Originally Posted by Brianma65 View Post
Is there a way to do this without the gauge. Can my friend use a once fired case from his gun?

Brian, yes there is,,,cut and trim a small piece of masking tape and stick it to the base of one of your sized cases, ( no primer or powder)

Make sure the tape doesn't extend outside the edge of the base,

Now, insert that piece of brass into the chamber of your gun and slowly close the bolt,,,it shouldn't,,,the masking tape is approx. .004" thick. Mine is anyways, lol,,check with calipers which you seem to have,,

If your bolt closes easily you are oversizing your brass,,more than .004,,

 

[tjhaile]

There is nothing incipient about a case that comes out in two pieces. An incipient separation is were the case hasn't completely separated, but shows signs that it is starting to fail. Typically, these are a bright ring around the circumference and/or a partial split of the case body (as in post #17). Sometimes the thinning of the case is not visible on the exterior and con only be detected by feeling the inside with a dental pick or paper clip.

 

[Brianma65]

There is nothing incipient about a case that comes out in two pieces. An incipient separation is were the case hasn't completely separated, but shows signs that it is starting to fail. Typically, these are a bright ring around the circumference and/or a partial split of the case body (as in post #17). Sometimes the thinning of the case is not visible on the exterior and con only be detected by feeling the inside with a dental pick or paper clip.

We inspected the cases and found several more that has a bright ring around them ,about a third from the case head. It's a perfect ring and these brass are 4 times used.

 

[Hitzy]

The problem with a neck sizing dies is the case shoulder will need to be bumped back when the case becomes hard to chamber. I'm a fan of full length resizing and the case fitting the chamber like a rat turd in a violin case.

Please notice below that Kevin Thomas worked in the Sierra ballistic test lab and now shoots for Team Lapua USA.

I don't see how this applies to the average Joe that buys a 40-50 year old commercial sporting rifle for hunting and off the shelf dies for reloading as the OP has....
Whether in the "lab" or when shooting for "Lapua", Mr Thomas is using custom cut match barrels & professional grade custom dies, the chamber and brass are known controlled dimensions, both are set and cut prior to a single round being sized and fired. We don't have that luxury, or the luxury of "scrapping a barrel when it won't hold 1/2 MOA".
In order to come close to the lab environment where FL sizing only reduces the case by 1-2 thou in all 3D directions, we would have to send a fired case or chamber cast off to a custom die maker and have it made to spec. Mass produced factory dies and rifles have varying tolerances, your FL die could be sizing 5 thou below SAAMI spec and your chamber could be 10 thou over SAAMI spec. Or you could have a fat chamber and your FL dies are over working the brass walls even though you are only bumping the shoulder back 2-3 thou.
Anybody with a .303 Brit will confirm that neck sizing is basically mandatory if you want to get any kind of life out of your brass, and it's not even a high pressure round compared to many of the common cartridges today. I've experienced that first hand as well, and brass being garbage after as little as 3-4 FL sizings vs 20+ neck sizing...saying neck sizing doesn't extend brass life is blatantly not true....

 

[Brianma65]

Brian, yes there is,,,cut and trim a small piece of masking tape and stick it to the base of one of your sized cases, ( no primer or powder)

Make sure the tape doesn't extend outside the edge of the base,

Now, insert that piece of brass into the chamber of your gun and slowly close the bolt,,,it shouldn't,,,the masking tape is approx. .004" thick. Mine is anyways, lol,,check with calipers which you seem to have,,

If your bolt closes easily you are oversizing your brass,,more than .004,,

it took four pieces of tape , measuring .005 , before the bolt had some resistance . We're now going to resize the case without the cam over , and adjust the die in at small increments .

 

[kamlooky]

To neck size only, I've used the paper clip method.
Bend a paper clip in a U and unscrew the die a bit, fit
the altered clip between the press and die and screw the die down.
This method should be enough clearance to neck size only and
not push the shoulder back.
Might be worthy of a try before one goes and purchase another die.

 

[Brianma65]

I have resized a case with the die about an 1/8 inch from the shell holder and kept repeating the process and screwing the die in, in 1/4 turn increments until it went well past the cam over. And there was zero resistance in closing the bolt.

 

[liberty]

What you want to be doing is turning out the die or unscrewing it to decrease the bump on your brass..

Lower the ram until it contacts the shelholder ..then turn out the die 2 full turns..lube a piece of brass and run it through. .this will likely have no effect on the case..

Start turning in the fls die 1/8 of a turn until you start to see an impression the neck of the case ...this impression may be 1/4 to 1/2 way down from the case mouth..you may need to angle the brass into the light to see this .

This is what some refer to as partial full length sizing. .sizing the neck but not the body with a fl sizing die..

At this point you have not reized the case body..now start to pay attention..keep turning the die in, in very small increments ..remove the case and try it in your chamber, closing the bolt slowly..feeling for resistance...the goal is to close the bolt of your gun on a case with just a little resistance..at this point you might say you have a zero headspace condition..

I like to have .001-.002" bump from this point on my brass for best function. .

This is where a headspace gauge is invaluable..

I have found even tightening the lock ring on the fl sizing die will effect the setting...

 

[Brianma65]

What you want to be doing is turning out the die or unscrewing it to decrease the bump on your brass..

That's the plan, I guess the brass is being put under a lot of pressure from being FL sized with a cam over, every firing.Thereby causing a weak spot in the brass, where its separating. If we back the die out so that it illiminates the cam over it should be good.

 

[Suputin]

FWIW the sizing does not cause the thin spot in the case. That is a result of the firing process. The firing pin hit pushes the case fully forward, then pressure causes the case to expand and grip the chamber wall. The case then stretches back until it co,Es up against the bolt face. This causes the case to thin out just ahead of the thicker web portion.

 

[yodave]

it took four pieces of tape , measuring .005 , before the bolt had some resistance . We're now going to resize the case without the cam over , and adjust the die in at small increments .

brass fired in that rifle that had the shoulder pushed that far back may not stretch enough on the first firing for this method to work.

 

[Brianma65]

FWIW the sizing does not cause the thin spot in the case. That is a result of the firing process. The firing pin hit pushes the case fully forward, then pressure causes the case to expand and grip the chamber wall. The case then stretches back until it co,Es up against the bolt face. This causes the case to thin out just ahead of the thicker web portion.

We put 4 pieces of masking tape on the case head , measuring .005 per piece. So .020 in total. Before we felt any resistance in the bolt closing. We then removed the tape and no matter how we adjusted the dies we could not get any brass to fit snug.
Anyway as I'm soon to be reloading 7mm for my tikka Varminter , I'm ordering a headspace comparitor.

 

[yodave]

We put 4 pieces of masking tape on the case head , measuring .005 per piece. So .020 in total. Before we felt any resistance in the bolt closing. We then removed the tape and no matter how we adjusted the dies we could not get any brass to fit snug.
Anyway as I'm soon to be reloading 7mm for my tikka Varminter , I'm ordering a headspace comparitor.

that brass has had the shoulders pushed to far back as it is, you need to set the die new once fired brass in order to achieve the results your looking for.

 

[Brianma65]

brass fired in that rifle that had the shoulder pushed that far back may not stretch enough on the first firing for this method to work.

So FL sizing, using a cam over every time is causing this right? So isn't FL sizing with a cam over basically bumping the shoulder back? Would it be good to FL size with a cam over on the first firing, then for the next few resizes , just back the die out ,so that the cam over is removed?

 

[yodave]

So FL sizing, using a cam over every time is causing this right?

yes, everytime you size to that degree your setting the shoulder back 20 thou, toss that brass and send me a PM with a address and I'll get you some dull looking range pick up brass that is once fired that you can play with

 

[Brianma65]

View attachment 43267View attachment 43266View attachment 43265I appreciate that offer Yodave, but my buddy has about a thousand once fired brass kicking around. I only reload handgun and .223 brass and have had no issues. Im just trying to help him get his prob figured out. But I've just ordered a 7 MM and I don't want these issues. I've found a couple of products for belted magnums. Worth buying ?

 

[yodave]

not if your using brass from your rifle only and no once fired range pick ups, as for the neck indicator, either that one or the hornady case comparator set