7mm mag using Petersen Brass versus Nosler brass

[Montana'eer]

With my 7mm-mag I started with Nosler brass for years, then I switched last year to Peterson. I had a load worked up with 70gr of X Brand powder in Nosler, achieving 3100 fps with my bullet choice. When I started with virgin Peterson I went down almost 2.0gr with same X Brand of powder and chrono'd it- got higher velocities than with Nosler. I backed it off a full 3gr and honestly started over. I'm not even thru 1/2 of my first firing with the Peterson brass either. I'll be tweaking it a bit more once fire formed.

It's a journey for sure. No one is necessarily right or wrong, but everyone should play it safe.

 

[MJN030]

I had this exact same experience when I switched to Peterson brass in my 7mag. Had a great load with RP brass already but when I switched to the Peterson it was all over the board, speed and accuracy both. It was extremely frustrating, thinking I wasted time money and effort to go backwards. After the 2nd firing and all fireformed up, it now runs just as before with the RP. Very consistent tiny groups with a little extra velocity compared to the RP. I also after FF can run same load in both brasses with no issues, only a bump in speed with the Peterson which was somewhat expected.

Ok I'm off to the range today .

I have 10 of the Petersen once fired brass .

I have read a of these posts and I have slowed down the charge . So I'll see how the grouping works . ( hopefully better ) There were no pressure signs
When I shot this brass originally .

But there was a thread in here that suggested that pressure signs could show once it has been fired .

So I took 2 grains off the charge .

I also made up the Nosler brass .
Just to make sure that's still grouping well .

I let you know the results .

 

[victor3ranger]

Did you just neck size and bump the shoulders back.002-.003?

 

[MJN030]

No I did a full resize , after cleaning ..

 

[MJN030]

So the results are excellent .
I just got back from the range and the petersen brass shot extremely well .

Bullet 145 HHT
Powder : 67 gr of H1000
Neck tension .003
.020 off lands .

.8" groupings .

So the issue is I dropped the powder charge because that was suggested .
As a result much more accurate .

So now I'm off to fire form the new petersen brass and get this brass ready for elk hunting .

 

[victor3ranger]

Congratulations, sounds like you are off to the races