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This is about .357 loads for a Henry carbine. Not high power - 8gr Lovex D032 (Accurate #2) - just short range target loads.

About 3 months ago, i had a case shear off in the breech. The rim and about the first 3/16" extracted but the rest was left in. Managed to eventually get it out. The break was a perfectly even circle. This was a PPU case that had only been reloaded once or twice.

Today I was starting to reload a large collection of once or twice fired cases from the same batch of PPU brass. I was just decapping and inspecting - and I found another 10 or so (out of about 100) that showed very faint signs of a sharp 'ring' around the base of the case.
(I know there's always a ring around the base due to the resizing die not getting right down to the rim but this is different - a more sharply defined mark.)

Does the team think this sound like a dodgy batch of cases or could something else cause it? (Bearing in mind this is not a 'hot' load!)

Thanks

You don't mention what bullet weight you use, but the maximum load shown in Explosia's load data is 7.6gr for a 158gr FMJ bullet. So are you really sure that 8gr is a "light" gallery load? According to Explosia, the maximum pressure rating (CIP) is 3,000bar and the aforementioned 7.6gr load is 2,940bar.

Did you do load testing beyond your 8gr before settling on it? You could very well be re-using cases loaded beyond maximum published loads which are then shearing after the next firing.

Looking at the published load data for this powder I would call your loads hot. Too hot.
You want to be looking at .38 load data in a .357 case for a nice accurate and soft load.
You only need to punch a hole in a piece of paper not knock down a bear :)

Sorry - finger trouble! 6gr and a 158 bullet.

When I was using Accurate #2 my .357 loads were about the 4 gn mark, with a 158gn hardcast TC bullet in a .357 case... fine for 25 and 50 yds

Daryll wrote:When I was using Accurate #2 my .357 loads were about the 4 gn mark, with a 158gn hardcast TC bullet in a .357 case... fine for 25 and 50 yds

Good to know, but the Explosia recommended load for a 158gr LRN is 6.2 so i don't think i'm over-driving it!

(Should also have mentioned that I got the load from a couple of other shooters who've been shooting it happily for years.)

Have you worked the load up? What is good in one persons rifle is no indication that it will be good in another persons rifle. Therefore good hand loading practice dictates that all new loads be worked up from the minimum recommended load, in this case 1/10th of a grain increments, did you do this in your load development?

What is the neck tension on the bullets?

Are the cases trimmed to the correct length?

Have you loaded/fired the cases your self from new/unfired?

Have you had the headspace checked?

Have the cases ever been annealed?

Has this load been chronographed when being fired from your rifle? If so what was the velocity?

I looked up the load data and as usual it is for pistols not rifles, so there are pressure changes.

I've never user the powder but I doubt it's a light load.

Would it being a double base powder make a difference too?

I've never had a pistol case head separation in my life, if the loads are not too hot I would suggest it's your cases. Does it happen with any other brand of case??

You've not been firing lead .38 specials in it have you?

It is not an infrequent happening with BPCR straight wall rifle cases, it is usually with them a function of top end loads and the case being short in the chamber, over a few firings the case stretches to fit the length of the chamber at the case mouth lip on the freebore/start of the leads this weakens the case at the head and separation is the result. Various case stretchers have been developed for lengthening the cases to fit the chamber and stop the separation. Tight chambers, soft bullets, high ( for the cartridge pressures and thick brass can also be an issue where upon combustion there is insufficient room in the chamber for the case to expand sufficiently to release the bullet so the case moves with the bullet till it hits the case mouth step.

So not totally uncommon with straight wall cases.