Necking down 300 SAUM to 7mm question

[pmarauder]

The necking down process from 300 to 7mm went perfectly. My question now is with my 7mm SAUM chamber OAL being 2.045 and the original Nosler 300 SAUM brass OAL being 2.005, After necking the brass down and trimming to uniform length (only had to trim .001) my cases now measure 1.995 for all 50. Will the necked brass grow once fired ,050??

Are these numbers acceptable? Im sure many of you have done this same process many times.

Thanks

 

[wooger]

I don't recall offhand how much shorter in the neck mine turned out to be, but I can tell you that they work just fine. I don't think they will ever grow that much.

 

[alf]

Mainly I did it to gain some neck thickness to turn the necks. I wasn't concerned.

Look at the bright side, you won't have to trim this year. ;D

 

[TheBlueEyedBear]

Derek,
How did you neck down your brass? Did you use a bushing neck sizer die, a seater die, a case forming die, or what? Just curious.

 

[jamesh]

pmarauder,
My brass typically grows .003 per firing. I had my reamer ground for a trim length of 2.000", max case length is 2.015". The Nosler brass is good enough that I went with a no-turn neck .318". Initially my new brass after first sizing is around 2.003" so your right in the ballpark.

alf,
You aren't going to shoot a 7 SAUM in competition are you?

Barry,
I have a Hornady custom die that I use to initially neck down the cases but have used the RCBS FL bushing die that I normally size with and it seems to work ok as well.

James

 

[pmarauder]

Barry... my process for necking down the brass is as follows.

Used a custom Forester honed FL die (.310) to neck down with lots of lube.... Expander ball was installed and case necks measuered .314 after sizing due to expander ball. I used the expander ball so brass would flow more evenly during sizing.

Then used the KM expander mandrel and neck turned all brass to .013 thick

once turned, i then resized the necks in my type S bushing die (.308 bushing)
my chamber is a .313, loaded round is .310 OAL on the brass is 1.995

 

[TheBlueEyedBear]

That sounds like the perfect way to do the job. Keep me posted when you shoot the new gun. Hopefully your scope will be here soon.

 

[sailhertoo]

What scope did you go with? Inquiring minds....

 

[TheBlueEyedBear]

PMAURADER and I both went with Nightforce 8-32x56 NSX scopes on our 7SAUMs. His is at the painter now getting matched up with the paint on his gun. Mine is still at the 'smiths' getting a BARRET BORS unit installed. Think I may have to go back to college to learn how to use this thing.

 

[sailhertoo]

I just got the 12x42 bench rest in yesterday. Thought I'd give it a try. 1/8 moa and ch-3 ret.

I've got 2 NXS's that I like but feel I would benafit from the ch-3 and the 1/8 moa in F-class.

Would like to here how you like the BORS!

 

[alf]

alf,
You aren't going to shoot a 7 SAUM in competition are you?

I tried everything under the sun to try and get a Sendero to be competitive at 1K in the stock class. The best it would agg was 1 1/2 MOA.

I'll keep on struggling with a Dasher..........

 

[jamesh]

alf,
You aren't going to shoot a 7 SAUM in competition are you?

I tried everything under the sun to try and get a Sendero to be competitive at 1K in the stock class. The best it would agg was 1 1/2 MOA.

I'll keep on struggling with a Dasher..........

Whewwwww.
Thanks I was getting a little nervous there.
Although with the Iowa range gone chances of seeing you next year aren't real good.

James

 

[alf]

James,

Ya gotta come to Harris,

The water's fine.............. ;D

Al