A project gun I've been working on for a while has given me a horizontal neck crack half way up the neck. I have also got primers coming out of the case. The first loads I tried were a recomended load and should not have been hot. I backed way down and still got the problems.The lighter loads only gave me 1 out of 4 primers backing out. My thought is a tight neck in the chamber, or short neck. I did not crimp and it was new brass from two makers. Any ideas?

what caliber and what load are you using.
My opinion would only be a guess and I know it would be wrong.
how bout some detail.
Dave

quote:

Originally posted by PoppaW:
A project gun I've been working on for a while has given me a horizontal neck crack half way up the neck. I have also got primers coming out of the case. The first loads I tried were a recomended load and should not have been hot. I backed way down and still got the problems.The lighter loads only gave me 1 out of 4 primers backing out. My thought is a tight neck in the chamber, or short neck. I did not crimp and it was new brass from two makers. Any ideas?

I can't recall anyone with that type of neck cracking in my experience. That seems strange.

Loose primers sure sounds like a pressure problem, though. I'd do a chamber cast right off to see how your brass matches.

Its a 404 Jeffery. The first load was 82gr H-4350 then I went to 72gr. The velocity should be below 2000fps with a 400gr bullet with the last load. If its pressure issues then its not from the amount of powder. Thats why I figured something in the neck.

what bullet are you using are they cast, copper or solid?
compare a new case to one that has been fired.
measure the neck of the fired case and compare it to one with a bullet seated (the diameter)
do the chamber easy?
Are you partial neck sizing?
Like tate said a chamber cast would be very benificial.
the 404 jeff is for all purposes just an up grade of the 450/400 nitro.
Dave

What's the history of the cases you're using?

I have had horizontal cracking on case necks at the location of the base of the bullet. They were loaded with old WWII 4831 that deteriorated. This caused stress corrosion cracking of the necks.

If your brass is really old or was used with some bad powder or stored at high temperature you might have this problem.

The primer backing out issue is not related.
The .404 does not have a sharp shoulder so it is very important that the chamber be the proper depth and the brass has to be sized exactly to prevent it from appearing to have a head space problem.

I suspect your primer problem is completely unrelated to your case neck problem.

As I understand it, your primers protrude only with your reduced loads. IF that is correct, then I am not at all surprised...it often happens with substantially reduced loads. The mechanism for that is...the primer ignites, setting off the powder and simultaneously forcing the primer a little bit out of the primer pocket. Because of the reduced pressure, the case expands enough to "sort-of" grab the chamber walls, just like any case does during firing. BUT, not enough pressure is formed in total to force the case back over the primer and firmly up against the bolt-face. So the primers still protrude after the firing sequence is over.

Many times in the old days (it was very common with .30-06 match loads of some shooters) the shooter mistakenly thought it was excess headspace, especially if he/she was a relatively new handloader. Nowadays so few people use reduced loads that the word about that phenomenom doesn't seem to very widely known.

So, I don't think it has anything to do with your case neck problem, although in very rare circumstances it MIGHT.

The only thing off-hand I can see happening theoretically which would damage case necks with low-powered loads would be this...the case neck expands to grab the chamber neck, but due to the thickness of the .404 brass, does not very firmly grab the rest of the chamber. The brass moves back SOME, stretching the part of the brass just below where it is grabbing the chamber neck.

IF the brass was hard enough and therefore brittle enough, a couple of times of that, and it MIGHT crack. But, that is theory. In real life, I think it would be almost impossible to creat a load balanced just right (wrong?) to crack the necks and still let the primers protrude.

Even if one tried to build loads like that, I doubt very much success would be achieved, as pressure builds from the ignition point of the powder outward in all directions, and the neck area would likely be about the last point to be pressurized.


It is easy to test for, though. Load mid-range recommended loads and see if either the case-neck cracks or the primer protrusion goes away. I would be willing to bet at this point that the primer protrusion would, but not the horizontal neck cracking.

So, that brings us to some questions:

1. - Is the gun built with a rechambered 10.75x68 barrel? If so, then the new chamber is about 5 m/m/ longer than the old chamber, and there may be a tiny step in the chamber neck right about where one would expect you're experiencing the cracks.

2. Is the brass made by a reputable, experienced large commercial ammo firm...or a small outfit that really doesn't have the experience of having made hundreds of thousands of rounds of .404 brass? If the latter, are their brass draw processes really engineered/performed correctly? their draw dies or set-up and/or operation may be faulty and set up flaw-lines in the final product.

3. You mention, I think, more than one make of brass being used. If that is correct, then it is not a faulty batch of brass "coins" from which the brass is drawn and likely not two different brass drawing companies making the identical mistakes in the draw process either. But if it IS only one batch of cases, there could be brass flaws in the batch of brass coins or "slugs" from which the cases were made.

4. Have you ever used over-powder wads in your loads? If so, you could be "ringing" the inside of the brass upon firing (and maybe your chamber too!). This COULD lead to brass failure in extreme instances.



There are many other possibilities. Wish I was where I could walk through it with you, looking for the answer.

Good Luck,

AC

AC, Thats great you covered about every senareo //

WOW, AC ... Very informative.
Have you tried to anneal your brass?
How many times have they been fired?

I m lucky enough to have a gun smith not far from me.
But on top of everything else here I would slug the barrel too for good measure.

Do you by chance have access to a chronograph?
In some cases simply finding out that you thought you were shooting a load for FPS A but your really shooting at FPS B ... if your lucky its not load Z!

Sometimes it can just be something over looked during the loading process too.

I do hope this helps too.
Good luck keep us posted.

The 10.75x68 idea may be what happened. The bbl says 404 on it but it is scuffed a bit. I really felt the necks and it seems a hair smaller above the crack. Maybe this is it. As I stated in the first post it is New brass. I used Norma and RWS.
I have seen primers come out on mild loads before and wondered but the neck line made me think pressure from another source. Like short or tight neck. I have the gun with me so will look at the bbl markings closer to see about a rechamber. I don't use fillers. I have shot 8 rounds out of this gun now. Thanks for the info.

quote:

Originally posted by PoppaW:
The 10.75x68 idea may be what happened. The bbl says 404 on it but it is scuffed a bit. I really felt the necks and it seems a hair smaller above the crack. Maybe this is it. As I stated in the first post it is New brass. I used Norma and RWS.
I have seen primers come out on mild loads before and wondered but the neck line made me think pressure from another source. Like short or tight neck. I have the gun with me so will look at the bbl markings closer to see about a rechamber. I don't use fillers. I have shot 8 rounds out of this gun now. Thanks for the info.

Do you have or access to calipers or micrometer? If you haven't yet measure the case?
It would be interesting to see how the case neck comes out.

I will track down calipers. I looked at the bbl stamping and the '404 Rim' is clean and the proof stampings have a small scuff under them. Does not look like it was changed after it left the shop. I still think the 10.75 thing is my best route to follow. If this is the case ( pardon the pun ) then can that lip be smoothed out so its easier on the brass? This stuff isn't cheap.

I m no smith but did repair fire arms in the army. But I m sure someone with the right knowledge could hone/smooth that right out.
If anyone knows otherwise or different method please let me know.

Nothing wrong with the brass . Cast your chamber and check all specs quit guessing .

It saves time in the long run and as James said , if it's a rough spot polishing it is the answer.

A C ; KNOWS HIS STUFF !.