Brass Failure

[jimbires]

I measured a standard case neck and from base to mouth it was .438" while the AI case neck was .464" so you're looking at .026" difference. I believe the case failure is caused by the shoulder being set back to form the 40* shoulder.

rodger i believe you have it right, from the photos its looks like that the failure occurs right along that line. I have seen other improved cases fail along the same line. It's got to be a weak area and resizing makes it fail faster than would be consistent with a standard case.

I'm going to split a case into and see if I can see the problem from the inside since I have several that have not lost the necks. That should show the crack forming in the crease at the bottom of the shoulder and neck.

I'll be interested in hearing what you find, when you cut a case . please let us know .

 

[truck driver]

Here's some pictures of cases I cut in half to show what is happening.
(click on the pictures to enlarge them) You will see what looks like a donut just above the shoulder on the inside of the case which is an optical allusion since there is no ring there,
You will also see cracks in the out side of the necks that are star shaped and extends thru the brass. In the bottom picture you will see where the case neck has started to break thru. There is also no stretching in the web area of the brass and all the problems are in the neck and at the base of the shoulder. This has only showed up in well used brass.

Also have some fire formed Rem brass that I haven't used since the Nosler brass had the larger H2O cap but will load it to see how long it will last. :mrgreen:

 

[jimbires]

interesting , thanks for your pics . I don't have anything that is AI . you have great case life , you just have to watch for this . thanks again.


my eyes are not what they once were , up close . how I've been looking for cracks is to put a small stylus flash light against or into the neck, and look for light coming through . I use one of these bendable ones . it's handy around guns and reloading .

https://www.amazon.com/Streamlight-6541 ... 2WXJ30FG91

 

[truck driver]

Jim I wear a magnifying visor when reloading to check for defective brass. The brass is ran thru the Dillon brass cleaner before reloading and makes it easier to see the cracks and defects.
I'm also thinking this will happen with any fire formed case whether it's an Ackely or other type that changes the shoulder and neck area.

 

[truck driver]

One more wrinkle to this problem could have been by sizing the brass on my Dillon 550 so I didn't have to keep changing dies. With the replaceable tool head on the 550 you have some play do to the clearance which is needed to slide the tool heads in the machined track of the press. The up and down play could cause the neck to stretch and the weak point is at the base of the neck.
There is a kit that is made to clamp the tool head into the press to make it solid but I'm thinking of either just using my RCBS single stage press for all reloading stages for rifle or using my Dillon 450 which has a solid head and is not replaceable.

 

[Dwh7271]

TD,
Don't know if the others have mentioned this or not but take a paper clip, put an 1/8" or so 90 degree bend in the very end. Run it into your case neck and slowly move the bent part up the case wall into the neck. Other than the obvious turn for the neck, what you're looking for is a little tick or catch as you move it upward. What you're really hunting for is a small doughnut in the case. Not sure at all but where that separated is where a doughnut could form from either forming or resizing. Maybe see if the others have it?

 

[truck driver]

TD,
Don't know if the others have mentioned this or not but take a paper clip, put an 1/8" or so 90 degree bend in the very end. Run it into your case neck and slowly move the bent part up the case wall into the neck. Other than the obvious turn for the neck, what you're looking for is a little tick or catch as you move it upward. What you're really hunting for is a small doughnut in the case. Not sure at all but where that separated is where a doughnut could form from either forming or resizing. Maybe see if the others have it?

Thanks for the tip Dewey. I have done that to check the the case web for stretch but didn't think of using it for the neck.
How's the new job going?

 

[Dwh7271]

Good, thank you!
Keeping me covered up though.

 

[Polaris]

This is a good reason to separate your brass by lots. Different brass, caliber, load, rifle combinations will stress your brass beyond serviceability at different rates. For example, I have a Savage M99 in .300. The M99 is a notorious brass stretcher. With Win brass, I get a maximum of 5 firings, with the neck splitting first. With Rem Brass, I get signs of separation around the web at about 4 firings.

In the case of your .35 WAI, you are basically starting with a case fired with excessive headspace in the fire forming process. I would consider this a severe use, and will reduce the overall life of your brass regardless of annealing. Going forward, considering the time spent in load development, case forming and annealing, I would sort into lots and discard a lot when they start to show signs of deterioration.

I typically follow the 10 firings, 3 trimmings rule in most of my rifles. Chuck it when any of those criteria are met or condition indicates impending failure. Some of mine do not or should not make it that far. The M99, M1 and AR 15 fall into the latter category. In the case of the M99, they just don't last. With the M1 and AR, they are both very hard on brass with the loads I am using. The brass for those is inexpensive and readily available. I automatically discard that brass after 5.

 

[Dwh7271]

Polaris,
Good points and info.
Not trying to hijack the thread or sharpshoot your post (it was a good post) but wouldn't the .004 crush fit on AI's take care of the headspace issue? As I understand it, that's why you "crush em". Granted, the body and shoulders still have to blow out for the improved cartridge.
I do agree that forming is a little bit of a torture test....but it's fun and they look cool. :grin: :grin:
Main reason I ask is I run a few improved cartridges and I haven't had any of what TD is experiencing.

 

[truck driver]

Thanks Polaris, with AI cases you seldom need to trim after the initial fire forming and only then to square the case mouth so all these cases that have failed have only been trimmed once.
One of the reasons I went with the 35W/AI was less case prep after fire forming the cases no longer stretch and to be honest about this I only check the case length occasionally while reloading the 35W/AI.
There are somethings I'm going to try and and see if it helps.
This brass has seen a lot of loads (10-15) and it could be I have just plain wore it out. I'm also thinking that when cleaning the inside of the case neck I'm removing metal and causing the brass to thin out which might explain the star shaped cracks that I see. Though I have used all the brass I have fire formed from Nosler brass for my load development the 10 pieces have probably been used the most since I would load and fire and clean the same 10 over and reload them again and again. I'm doing the same thing with some 7mm RM brass but have not worked with it as much as the 35W/AI. The dang thing is fun to shoot and is a constant challenge for me figuring out what it likes and doesn't like.

 

[truck driver]

TD,
Don't know if the others have mentioned this or not but take a paper clip, put an 1/8" or so 90 degree bend in the very end. Run it into your case neck and slowly move the bent part up the case wall into the neck. Other than the obvious turn for the neck, what you're looking for is a little tick or catch as you move it upward. What you're really hunting for is a small doughnut in the case. Not sure at all but where that separated is where a doughnut could form from either forming or resizing. Maybe see if the others have it?

I did some further investigating this mourning and didn't find a doughnut even in the cases I dissected. One thing I did notice is that the thickness of the brass tappers from the case mouth and gets thicker as it tappers to the web.
I also measured the thickness of the brass at the case mouth of new unfired brass and brass that had been fire formed along with the brass that had cracked. the Nosler brass new unfired measured .013" fire formed it measured .012", Rem bras was .012" new and the same fire formed so there was so brass flow with the Nosler brass but only during fire forming.
From the bass of the neck to the base of the brass Nosler is 2.044" while the Rem brass is 2.025". SAAMI is 2.060".
Rem case neck length is .460" and Nosler is .448". And fire formed new Nosler brass comes out to 2.461" and the Rem 2.477" this brass started out at 2.472" for the Nosler and 2.477" for the Rem. The Nosler brass shortened up but the Rem brass stayed the same.
I think I'll find some Norma brass and give it a try.

 

[Polaris]

If you're getting 10-15 firings, your brass is most definitely just worn out. It is a reuseable but expendable component, and will eventually fail.