New load question, Dents after firing.

[DUNEZRUNNER]

I made up a few loads to try out for this years hunting season. The gun is a 300 weatherby. I shot the first round and when I inspected the case for signs of pressure I noticed that right below the neck of the case there were 2 dents about 1/4" long down the case. I thought this was odd but there was a slim chance I didn't see the dents before I fired the case. I got a second round out and thoroughly inspected it before I fired it. After I fired it I noticed that this case had the same dents in the brass. I stopped using this batch of ammo cause I had no idea what was happening. I proceed to shoot another batch of ammo that was loaded exactly the same but with 1 grain more of powder. This ammo shot perfectly with no signs of pressure or any abnormalities.

I was wondering if anyone knew what could have cause these "dents" in my case. I will try to get some pictures of them tonight.

Any info would be greatly appreciated.

Thanks

Thomas

 

[ScratchnDent]

The only thing that I know of which would cause dents would be oil or carbon fouling in the chamber.

 

[OYE]

Gas is leaking by the neck. One of the Speer manuals, # 10 I believe, mentions it occurs
in magnum chambers with too much freebore. They recommend changing powders if it persists. Perhaps the heavier charge will stop the problem. A case split or separation can also cause this. Discard the brass of course.

 

[Walkalong]

OYE got it. Low pressure. The neck doesn't seal the chamber well enough, the gasses get back into the chamber area and push dents in the brass. Not enough powder, or too slow of a powder.

Welcome to THR

 

[Captcurt]

Gas is leaking by the neck. One of the Speer manuals, # 10 I believe, mentions it occurs
in magnum chambers with too much freebore. They recommend changing powders if it persists. Perhaps the heavier charge will stop the problem. A case split or separation can also cause this. Discard the brass of course.

Oye, You hit the nail on the head!

 

[ScratchnDent]

That's why I love this place...I just learned something new.

 

[DUNEZRUNNER]

Thanks, I am guessing that was the problem. What I don't understand is that this load was 1 grain lower than the MAX recommended load in my book. I raised the load the 1 grain to the MAX load and I had no problems.

Thanks

Thomas

 

[OYE]

It's not a very common problem. You may wish to take Speer's advice and try changing powders, in this instance.