7-300 Win. Brass options?

[AZShooter]

I recall reading an article called "make mine a 6mm-284". In the article the author had issues with primer pockets loosening. He felt the base diameter of the chamber was too large causing the base to expand too much. He had the reamer reground with a smaller base diameter. It solved his issue.

I wonder if the reamer used for your chamber had the wrong dimensions OR the gunsmith sanded/polished the devil out of that area making it too large. Not sure if this concept is viable because the 300 win brass uses a belt. Perhaps you can measure the base and belt area of virgin and fired brass to get a clue?

These days I only chamber wildcats with a reamer I purchased with my specifications. Life is too short to mess around with mystery chambers especially wildcats.

 

[BJH]

I will measure the cases to see if there are any issues there. I do know that if there is any kind of problem like that present, the gunsmith will fix it without any issues. Thanks for your thoughts guys. I haven't made it out to the range the last couple weeks. But hopefully I can find a fix fairly soon.

 

[el matador]

Its a good idea to check neck clearance any time you're necking down brass. Just measure the neck OD of a fired case and compare it to a loaded round. Ideally the loaded round will be .003 to .005" smaller. If you have less than .003" of clearance it could be giving you pressure issues.

Based on the fact that you're not seeing any other pressure signs I would guess the Norma brass is expanding too much at the web area. Thai means the brass is too small or the chamber is too big. Maybe compare some unfired Winchester and Norma to the fired brass and let us know what you find.

 

[BJH]

Well it seems that it was as simple as changing from Norma to Winchester brass. I did some measuring and found that the Norma brass dimensions just weren't working with my chamber. Switched to Winchester and found 2 nodes that worked phenomenally. With no primer pocket issues!

1st load:
Berger 195
68 grains Retumbo @ 2835 fps.
ES of 6 fps, S-D of 3 fps

2nd load
Berger 195
72.5 grains Retumbo @ 3024 fps
ES of 8 fps, S-D of 4 fps

Both loads produce 1 hole groups. Can barely tell there is more than 1 shot on the paper.

Thanks for reading my post and taking time out of your lives to try to help me! It is appreciated very much!