300 ultra brass from 7mm ultra?

Eastcoastshooter375

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I have seen ample supply of 7mmRUM brass but 300 is limited. I know the 338 ultra has a shorter body, but wasn't sure about the 7RUM.

I would expect the neck thickness would be off, but how much, I'm not sure.
 
I have seen ample supply of 7mmRUM brass but 300 is limited. I know the 338 ultra has a shorter body, but wasn't sure about the 7RUM.

I would expect the neck thickness would be off, but how much, I'm not sure.
When I tired out my 7rum I went to 300 rum and necked the brass up I already had in 7 rum. I've got over 100 rounds of this brass in use and the only issue I've had at all is a couple of necks splitting on the first firing. Annealing before necking up would probably stop this. For me it was simply staving off dropping a $100 bill on brass. As to neck thickness, it'll be a smidgen thinner but who cares; I'm still getting .5 to .6 moa from a 9# 300 rum without a brake.

Do a 50 and see if it works for you.
BTW, Lube the inside of the necks a bit so they neck up more evenly.
 
Lefty, I will definitely give it a try. I've got close to 120 emptys that are approaching retirement, but have 40-60 1x fired that should last a while. Just thought I might try necking up 7RUM in case 300RUM brass becomes even harder to find. Wanting to get things back in my "comfort zone" . Now if I could figure out how to turn 150gr noslers into 230gr Bergers.
 
I'm wishing for a few more 225 gr hornady pills too bud. Lucky the 180 and 190 hornady pills fly true also and I've got a few hundred each of those.
 
Are you saying that a person could run 7mm RUM brass through their FL 300 RUM die and it'll do? What all needs to be done to do this? I'm wanting to use up my 7 RUM brass.
 
Yes. It would be a perfect way to use up your 7 RUM brass and fill the need for your 300 RUM brass shortage. Run your 7 brass through the 300 fl die and your ready to roll.
 
It's essentially the same thing guys do with 300 Ultra brass to make 338 Edge although the 7mm to 300 up size isn't quite as much as making the Edge brass
 
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