Bad reloading decision

[Major Tom]

psteinmayer is right. Looks very suspicious. Case heads do not expand like that.

[Parashooter]

. . . Case heads do not expand like that.

They do when it's good brass, the breech gives solid support, and the excessive pressure is therefore confined in the case.



Case on right is normal, deprimed, .284 Win. formed to 7.5x55. Case on left was the same size until fired with the wrong powder (WC846 instead of WC852), generating estimated 82,000 psi. (Velocity of the 168-grain bullet was 3220 fps on the chronograph I was using - normal is ~2700.) Head expanded uniformly, with smooth K31 bolt face containing gas perfectly despite significant primer pocket expansion. Recoil was stiff but no gas escaped. Quality brass can take a lot of abuse.

The .268" Hornady 160-gr. bullet, designed for the 6.5 Carcano, has a history of pressure anomalies in long-throated barrels, particularly with slow-burning powders, apparently from sticking in the leade before sufficient pressure has built to overcome engraving resistance.

[dave]

Going from .264 to .268 should not raise pressure that much. Germans went from .318 to .323 with no problem, they did not rebore altho they did relieve chamber throat.

[Hefights]

With that much apparent difference in diameter, is the rifle damaged? Can you post a picture of the fired cases standing side by side? Chambers do not grow or stretch that much without a big problem. So perhaps there was a "flow" in the brass somehow but it survived, but the chamber cannot have stretched that much in diameter.

[Matt Anthony]

With that much apparent difference in diameter, is the rifle damaged? Can you post a picture of the fired cases standing side by side? Chambers do not grow or stretch that much without a big problem. So perhaps there was a "flow" in the brass somehow but it survived, but the chamber cannot have stretched that much in diameter.

For someone to use the wrong size bullet, when it's published as plain as day in every reloading manual, is just plain stupid! Yep I said it, STUPID and remember you can't fix stupid. Any time you reload any cartridge, double check your components, measure and weigh each component so there is no chance of making a very costly and stupid mistake that could cause harm to others and yourself.
Matt
Matt

[cwbuff]

In the this case the case head did expand. After the fired the cartridge, he could not open the bolt on the rifle - resulting in a trip to the gunsmith. The gun checked out with no damage. It is a Steyr Mannlicher-Shönauer 1903 Mountain Carbine. I'll take a pic of the standing cartridges today and post them. I'll also put the calipers on the case heads.

[cwbuff]

For someone to use the wrong size bullet, when it's published as plain as day in every reloading manual, is just plain stupid! Yep I said it, STUPID and remember you can't fix stupid. Any time you reload any cartridge, double check your components, measure and weigh each component so there is no chance of making a very costly and stupid mistake that could cause harm to others and yourself.
Matt
Matt

He had read on the web that some barrels on this gun were over sized and to use the larger bullet. So that is what he did. But he did so without slugging the bore to see what the barrel diameter actually was. DUMB - but lucky.

[cwbuff]

Good case on left, bad case on right
Good(L)-Bad(R)..jpg

[Hefights]

Wow, looks like it expanded and stayed that way, never "shrunk back" a little to allow extraction. So it just stayed "stuck to the chamber". You learn something every day.

[cwbuff]

Here are some case dimensions:
Case head: good=0.451", bad=0.474" to 0.484" (not round)
Primer pocket: good=0.205", bad=0.235"