Group differences in Weatherby Brass versus new Norma Brass

[TX mountain hunter]

I'm just curious if anyone has tested 30-378 loads that are identical with the exception of the brass. I have some once and twice fired Weatherby brass and some brand new Norma brass. I'm about to do some load testing and am wondering if this should be a variable or if there is negligible difference. Should I expect these to hit in the same location provided primer, bullet, powder, case length, and everything else is kept constant?

Merry Christmas!

[Boss Hoss]

No---even with the same brand of brass there are changes from lot to lot.

[TX mountain hunter]

Thanks Boss

[Willys46]

I may be mistaken, but doesn't Norma make Weatherby Brass? That was what i was always told.

As for hitting the same place, Possibly. Ya different lots have slight differences, but heck they could be the same. I would test them and see. I would venture that the slight difference between lots of brass would be hard for most shooters to tell the difference.(I am excluding the extreme cases)

With that said I do weigh all my cases and keep them in the same lot. I would say test them and see what you get, you may have to bump your powder charge one way or the others.

[ReachnOut]

You're not going to have much of a test unless you weigh and sort both brands and then proceed with the identical loads. In my experience you will be lucky to get 80% of a hundred cases to fall within acceptable weight tolerances. For me that is 1/4 gm. Some manufacturers tend to be less than 50% acceptable. The two you mention are among the best that I've been involved with over the years.

[FFEMT]

Another thing to keep in the back of your mind is: Along with weight sorting, are you full length resizing your brass or are you neck sizing only? If you are only neck sizing, then your brass has been "Fireformed" to your chamber and therefore should theoretically have a more balanced internal ballistic pressure for the once or twice fired brass. This will help give you a lower standard deviation in your muzzle velocity, which in turn will produce better accuracy. Providing that you precisley weigh (XX.00XXgrains) all powder charges and you are not "throwing" your charges. If you are throwing charges, then all bets are off. Also if you are shooting from a "factory" barrel, then you probably won't see a tremendous amount of difference, but you should see some.