What is this caused by?

[ziconceo]

Alright thanks for the feedback guys!!! I'll put a low power load in and reshape it

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[Witch Hunter]

No need for a light load, it will expand when fired, no problem.

[knucklehead0202]

not too low, I presume you're not loading at max anyway so you'll be fine dropping a grain.

[ziconceo]

not too low, I presume you're not loading at max anyway so you'll be fine dropping a grain.

It wasn't reloaded when I shot it though, it was a factory loaded round.

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[knucklehead0202]

no worries, I'm just saying don't run a max load when you reload it and you're cool. it'll reform just fine and give you lots of reloads for years to come. if you get another one out of that gun that looks the same, I'd start to wonder, but I think it's a fluke.

[ziconceo]

no worries, I'm just saying don't run a max load when you reload it and you're cool. it'll reform just fine and give you lots of reloads for years to come. if you get another one out of that gun that looks the same, I'd start to wonder, but I think it's a fluke.

I see, well thanks a bunch for the info! I'm gonna reload some mosin food!

[Wrangler John]

As some of the posters noted, that type of dent is caused by low pressure not forcing the case shoulder/neck junction into contact with the chamber with enough force to prevent gas from intruding between the chamber wall and case. The photo below shows similar rimmed cases with just such dents. In this instance the case is a .35-348 Winchester Ackley Improved. The .348 Winchester cases were necked up to .358" for .35 caliber bullets, loaded with a moderate charge of powder and fireformed. Because there was no loading data other than 60 year old loads from P.O. Ackley, I went cautiously as powders have changed over the years. A properly fireformed case is on the left. The case on the right has two dents set at approximately 90 degrees to each other. An increase in powder solved the problem. This is common in rimmed cases where headspace is set on the rim, where in the usual bottle necked cartridge it would be set on the shoulder, or shoulder/neck junction reducing chances for blowback. Your case dent was caused by that particular cartridge not developing enough pressure, not an overload. Just keep charges under the maximum listed in a published loading manual. In my case a 1 grain increase of powder from 43 to 44 grains, still well under maximum, proved to be the best fireform load.



These cases were saved for examples, I would not load them again as they would set creases which weakens the brass.

[knucklehead0202]

^^^^ well you don't get a much more graphic example than that. looks like Prvi owes you a little powder all's well that ends well though, at least the bullet exited the barrel.