8mm-06 case failure

[kjohn]

I decided to take my old 98 "sporter" out today. I have a supply of handloads, some with cast bullets, some with soft nose, some fmj, various powders. I fired some off that had cast bullets, brass cases. Powders used were AmmoMart 47SB and H4350. One round I felt some crap hit my forehead. The case was seriously cracked. There was no loud report, nor excessive recoil. My guess is that the brass was way too brittle to withstand the load.

 

[jamesharrison]

Brand of brass? Age
If you are using Ammomart's WC760 Slow Lot #10, by any chance is your H4350 also one of Ammomart's old OEM series powders, the early lots of which were made by Nobel, before being replaced by Vihtavuouri's N160?

Presume you know that a lot of Ammomart's old powders went bad. I know of at least 2 [33 & 44] of their powders which mostly went bad, along with IMR4320 [Ammomart's CL### something or other].

In your first photo [the blue UV?] what is the pile of brown dust?

Maybe pull some of your un-fired rounds down to see if there is deterioration.

 

[hawk-i]

that is exactly where the case thins out after multiple firings, best to always check with a sharp pick before reloading and use caution to not over bump your headspace when resizing.

 

[bearhunter]

kjohn, that looks exactly like some of the "squib" load cartridges we played with back in the day.

We were trying to Kaboom a Type 99 Japanese chambered in 7.7.

You could hardly give those rifles away back in the mid sixties.

There were all sorts of myths and rumors going around back then concerning the strength of Japanese firearms, which were debunked by PO Ackley and a couple of scientific institutions.

We had heard that squib loads could be made to detonate, rather than "control burn" so we thought we would test the theory on a cheap rifle known for being weak.

This Type 99 was one of the crudest, late war production pieces I had seen, and I saw a lot of them back then.

It was covered in rust, cracked stock, sewer pipe bore, parts missing, a classic JUNK grade firearm.

That was a long time ago and I don't remember the charge weighs of Super Vel that we used in surplus 7.7 Jap cases. We pulled the bullets and dumped the original powder, then put in a small charge of Super Vel powder and topped them off with .312 diameter 220 grain round nose FMJ, which were common back then.

The rifle came through the whole experiment looking just as good as when we started, however the cartridge cases, which were just over 20 years old at the time and about as factory fresh as was possible at the time, looked just like those in your pics when the charges started to get to the detonation point.

We never did get one to be much worse than those in your pics, because the powder charges got too small to ignite reliably.

Looking back, we were lucky to be using one of the strongest bolt action rifles built to that time.

 

[Andy]

Yes - brittle brass. Had that round been loaded several years ago? Powder that has gone bad within a cartridge can ruin the brass with which it is in contact.