7mm-338 RUM IMP Brass

[Bran743]

I'm getting ready to have a rifle built/rebarreled that is based off of a 338 RUM necked down to a 7MM with a 40* shoulder. My smith has requested that I make a round (minus the 40* shoulder) set at the COAL I want that way he can make sure the barrel is throated properly.

That being said, my question is what is the best way to get the brass where I need it? My thought so far would be to buy 300 RUM brass (since finding 338 RUM brass is about as scarce as hens teeth) and form it into 338 RUM, trim it to length, then neck down to .30, then neck down to 7mm.

Or is there an easier way I'm over looking???

-Brandon

 

[Rich Coyle]

Do you already have the reamer? I have one, unused, that is very close that you can use if you want. It is a 7RUM with the shoulder pushed back to be the same height as the .338RUM. This gives a .100" longer neck for better barrel life. The barrel company accidentally sent me a 6.5 barrel instead of the 7mm barrel I was going to use on my Klienguenther K14. So I used it to rebarrel my Weatherby 6.5SLR.

If you want I can send you a dummy round. But I don't want to be a salesman here so I can send you one like you are requesting. Which do you prefer or do you want both?

 

[HARPERC]

They aren't exactly the same case.

I'm not sure what you're end case looks like, but I think 7mm RUM cases are where you want to start.

 

[Bran743]

Rich Coyle, PM inbound shortly

HARPERC - I was thinking the 300 RUM would be better since it isn't as far to stretch, but if they aren't the same than that won't work.

Wouldn't having the .100" longer neck also increase the pressure that is created when the powder ignites????

Also I have the reamer print if anyone wants to see it.

 

[HARPERC]

Rich should be a help, he's been there done that. I'm just in the initial phases of mine.
I'm looking at the 7mm RUM case, necked to 6.5, so it's closer. Then fire form to a 40 degree shoulder. I'm not certain how much neck that leaves.

 

[Rich Coyle]

I found some stuff that might be of interest. For some reason the photos showed up in a random order. The first photo is of the reamer print. The second photo is a Berger 7mm VLD hunting 168 beside two wildcats. I have a reamer for the one on the right with the longer neck. The bullet was suppose to be at the bottom of the neck but I must have moved it without knowing it. The case on the left is a .338 RUM. The one on the right is a 7RUM. The third photo has a 7 RUM necked to 6.5 mm with the shoulder pushed back to match the .338 RUM. It holds 109 grains of water to the mouth. It pushes the Nosler 140 to 3,419 feet per second from a 28" barrel. The one in the middle is my 6.5 SLR. It matches a .264 Win Mag. The case is a 9.3X64 Brenneke. As you can see I like the Weatherby look. It is on the Mark V six lug untralight that was built for a .30-06. The action is not large enough for a belted magnum case. When it had its previous 26" barrel with a Swarovski z5 5-25X52 it weighed 6lb 13oz. The new barrel is 24" and larger diameter. I hope to have it back from the 'smith by December. The third cartridge is a 6.5mm Creedmoor for comparison.