black soot on brass

[Britz]

I was messing around testing some loads in my 300wsm. 64g vargete, 110g vmax and BR2 primers. I have shot them before and it seems to be a fairly moderate load. I decided to test seating close to the lands to see if it would affect accuracy much. I was only able to seat them 0.008" from the lands and that was absolutely it. The bullet was seated by about .02 or so into the case. I fired the first shot and immediatly could smell a strange odor from my rifle. Easy ejection and noticed that the case was sooty. SHot the next two with the same affect. Impacts were ok - 1.5" at 200 and the primers were not flat at all.

I was thinking that because the bullet was almost setting on the case that the chamber pressure wasn't able to make an immediate seal around the case causing some gas to leak out around the case and bolt before the case was pushed tight to the walls. Does this make sense? I dicided to abort the rest of my test shots with seating them so far out.
Thanks for your input, Mark.

 

[kraky]

Not exactly sure why but you nailed it on the head when you said that the case mouth isn't sealing. YOu could try seating deeper and see what happens.

 

[FOTIS]

Pressure too low. Not enough to seal all of brass against the chamber walls.

 

[Britz]

Thanks for the replies guys. I always feel better when I have someone else to back up my theories, especially when I am dealing with something that can potentially be dangerous.

 

[metallica]

I had the same problem with my 300wby. Bumped up the powder charge by .5grns and it solved the problem. I was loading at the lower end of the min charge.

 

[JD338]

Britz

You are spot on.
Try seating the bullet deeper into the case. You might also want to increase the powder charge weight.

Let us know your results.

JD338

 

[yeayow]

If it shot good enough for you try a LEE factory crimp die. It will probably increase you'll bullet pull pressure enough to take care of the problem. I've had good luck with them.

 

[Britz]

That same day I had test shots done with same chare and seated deep, about .2" off lands, and they shot clean and a 3 shot .75" group at 200. Next time I get to the range I plan on trying a little more powder and seated a happy medium.