I was at the range this morning and had 85 gr. of 7828 behind a 180 gr.SST in my 300 WBY and I shot the first of five and when I open the chamber the shell came out and there was not primer, the headstamp was imprinter on the bolt face and I never found the primer. The rifle was fine I didn't shoot any of the other four but did some lesser loads and everything was good.

My questions is this I have shot 85 gr. before and had no problems what so ever it was in virgin brass though. This is the second loading of this brass could that have caused the problem? If not what?

I would check the headspacing myself .Maybe then check the 85 grains to be sure that is correct .

Sounds like you had some serious pressure issues. I've never had that experience in over 40 years. If you didn't see the primer, I would suspect that it is somewhere in the magazine well. It may have wiggled under the follower. Take the action out of the stock and see if you can find it. Did the brass show any signs of cracking or separation in front of the belt?

You say you have shot this IDENTICAL load before, and had no problems....You changed nothing at all?
What air temp. was your load worked up at, and what was the temp/humidity when you shot it with no problems compared to the temp/humidity when you had the pressure problem?
Some powders are temp. sensitive and can cause problems at or near max loadings if developed in cold weather and then fired in much warmer weather.

Were you using a new lot# of powder,or was it from the same container as before?

http://jagt.net/Weatherby/300/load/180grain.htm

Reloading site for the 300 WBY

Always had good luck with the MRP and Reloader 22 in the 300 WBY and 300 Win

I have had it happen before. i worked up a nice load to max in 10F weather, and then summer time, I went over pressure.

But in yoru case, sounds like headspace. Are you full length sizing?

removed by RD

I checked the case and there was no damage, no cracking around the neck or separation around the belt. It look like the others that had less powder. I also checked my scale, these were the last loads I made so the scale is still set on 85 on the dot. The temp. when I was testing last time was 55-60 and this morning maybe about 70.

I did full length size.