7mm mag using Petersen Brass versus Nosler brass

[MJN030]

Hi guys , I've read a lot about Petersen brass and I agree it's really nice . I like it a lot .. but here is what happened .

145 gr Hammer Hunter Tipped (HHT)
69.0 gr H1000
Fed 215 primers
.025 off lands

Everything the same here except for the brass .

The Nosler brass shot < 1" 5 shot groups. @100 yards
The Petersen brass shot >1" groups 1.5" or greater .

The nosler brass has been reloaded several times the Petersen brass first time reloaded brand new brass .

The neck tension is .003 on all brass .

Why such a difference ?

Thanks
Marc

 

[xsn10s]

The Nosler was fired several times so the fit in the chamber is probably better. You'll probably have to work up a load using the Peterson brass and fire it a couple of times before making a comparison.

 

[Varmint Hunter]

Two things:

1. While new brass is formed to the chamber it is quite possible to get less precision than you will with properly resized fired brass.

2. The Peterson brass is probably thicker and likely has less powder capacity which would cause the pressure to be higher when using the same load. You may need to tweak the load to the new brass.

 

[waspocrew]

Two things:

1. While new brass is formed to the chamber it is quite possible to get less precision than you will with properly resized fired brass.

2. The Peterson brass is probably thicker and likely has less powder capacity which would cause the pressure to be higher when using the same load. You may need to tweak the load to the new brass.

Exactly - you changed a component and can't expect the load to shoot the exact same as your nosler brass. Work the load up again with Peterson brass and I'd imagine you will find better accuracy.

 

[Dmagna]

Because it's different brass, you can't just switch brass and load it the same exact way. Reloading basics 101, different brass has different case capacity. What you did is very dangerous and could lead to a catastrophic failure in some cases.

 

[MJN030]

Because it's different brass, you can't just switch brass and load it the same exact way. Reloading basics 101, different brass has different case capacity. What you did is very dangerous and could lead to a catastrophic failure in some cases.

In some cases …. But not this case …
I've been reloading for over 40 years .
Thanks for the education

 

[MJN030]

In some cases …. But not this case …
I've been reloading for over 40 years .
Thanks for the education

By the way .. I don't recall saying there were any pressure signs did I ?

Nope !

 

[MJN030]

Exactly - you changed a component and can't expect the load to shoot the exact same as your nosler brass. Work the load up again with Peterson brass and I'd imagine you will find better accuracy.

Interesting …. Thanks !

I thought it would be an interesting comparison .. I have to do something because I do not have enough nosler brass to go elk hunting with ..,

 

[Dmagna]

In some cases …. But not this case …
I've been reloading for over 40 years .
Thanks for the education

You've been reloading over 40 years and didn't understand brass would change load data? Sounds like you need to throw out the last 40 years and start over.

 

[MJN030]

You've been reloading over 40 years and didn't understand brass would change load data? Sounds like you need to throw out the last 40 years and start over.

Look ! I posted a question because I thought it was interesting . I'm sorry my reloading skills don't match yours.

You obviously are a master .

Why can't people just have a discussion rather than showing how great they are ?


Just so you know … this reloading data that I posted are with saami specs . There isn't one rifle that couldn't handle saami spec loads especially ones that are in the middle of the spectrum .

So again thanks for the education .

 

[victor3ranger]

I would really be interested in how it shoots after it's been shot once

 

[MJN030]

I would really be interested in how it shoots after it's been shot once

Yeah !!! Me too ! Maybe this week .
I just washed and did all the case prep work yesterday . So , stay tuned

 

[victor3ranger]

Yeah !!! Me too ! Maybe this week .
I just washed and did all the case prep work yesterday . So , stay tuned

 

[74honker]

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.