300 Win Mag reloading question

[Clem Bronkoski]

Ok guys I just acquired a 300 Win Mag in a Bergara B-14 HMR. Now I know initially I will have to full length size all my brass but what about after I fire it in my rifle?
Should I partially size my brass (back out the FL sizing die a bit), neck size only or FL resize for longer case life.
Inquiring minds want to know.

 

[Ckleeves]

Shoot your virgin brass, neck size for your second firing and then measure with a comparator after that second firing once the brass is fully fire formed to the chamber and FL size with .002 of bump from then on just like a non-belted cartridge.

I don't bother shooting all 50 or 100 pieces with that process, just take one or two pieces, fire them twice to make sure they are fully formed and then measure, set my FL die for the bump I want (or use a comp shell holder to make things real easy) and use that for the life of the brass.

 

[Ol' Red]

What @Ckleeves said pretty much covers it.

 

[asd9055]

I think by tomorrow you will have many different opinions/advices. Back when I was starting out, I had ONE rifle, One Cartridge. Folloing the advice of my mentor at the time, after the first firing, I only neck sized untill and only IF the rounds would not chamber. Then I would full size. It owrked good enough for my needs then. Now I full size everytime.

 

[memtb]

Ok guys I just acquired a 300 Win Mag in a Bergara B-14 HMR. Now I know initially I will have to full length size all my brass but what about after I fire it in my rifle?
Should I partially size my brass (back out the FL sizing die a bit), neck size only or FL resize for longer case life.
Inquiring minds want to know.

I only have your basic 2 die sets….nothing special!

I also use a belted case similar to the 300 WM. With mine I definitely "do not" contact the die to the ram… once the press has "cam'd" I back the die back a bit, and bring the press ram fully to the top.

Then try the case in the chamber. If you backed the die off far enough….the case should not be chambered. You continue this practice, lowering the die a bit (I go 1/4 turn), bring the ram up…..test the case for chambering.


I repeat this process until the rifle bolt will close with minimal resistance. I say "minimal" as this pretty much guarantees that there will be no case lengthening when firing.

I easily get 10 firings on my AI brass. Loads are at maximum (seeming safe) pressures….I'm pretty pleased with my case life! memtb

 

[Clem Bronkoski]

So you're only resizing a portion of the neck and not really neck sizing. A neck sizing die will only size the case neck. Doing what you're doing is still working the body.
There are two schools of thought on this. One is for neck sizing and the other for shoulder bumping.
I guess I'll try both and see what works for me.

 

[memtb]

Clem, if that was for me. You may be correct. But, I can see how far down the neck the die contacts - reduces the neck OD. I also know, that if I only go down a little way on the neck as indicated by the lube mark on the neck…..the case is difficult, if not impossible, to insert into the rifle chamber and close the bolt!


The search mentioned…..should I search here on the forum, or do an internet search!

Maybe I'm doing it all wrong….but, I think that I'm extending my case life! memtb

 

[wilehunting]

I had a Browning A-bolt 1 once that the chamber was somewhat oversized at the shoulder. I only neck sized the fired case to have the best case to chamber fit with a neck size only die. 300 win mag.