6.5 rum?

[barnesuser28]

Has anyone thrown around the idea of necking down a 7mm RUM to .264 caliber?

 

[diriel]

The problem is it would be severely over capacity. You reach a point of diminishing returns on such a large case with a relatively small bore. Take a look at the 6.5 STW or the 264 Win... but you are going to have HELL getting a 127gr Barnes LRX with it's G1 of .468 up to the 3750 / 3800 it will take to drive them to 1k and retain the 1600 fps you want...

Love the 6.5, and love barnes copper bullets but you are in for a rough ride sir.
Gary

 

[Fred Ea]

Why? A 264 Win Mag is just about all you want to reach optimal performance with the 6.5 caliber. Talk about overbore and a burned out throat in no time, that would be it.lightbulb
FE

 

[7stw]

Has anyone thrown around the idea of necking down a 7mm RUM to .264 caliber?

I would maybe entertain the idea of a SHORT action Ultra mag, but a long action 6.5 would not be on my bucket list. You would have a tough time find a powder that would give you good load density, without too much pressure. There really is a thing called TOO much of a good thing, and that one would certainly apply. In reality, I think that the smallest that you can go with that case is the 300. Even the 7 ultra way over bore, fussy to load for, and very abbreviated barrel life. If you are talking short action, that could be fun.

 

[Rizla]

It's been done already. Kirby Allen necked down a .338 RUM (just a necked up .300 RUM, which is the parent case for the 7mm RUM) to .264. He calls it the 6.5mm Allen Magnum. It can launch a 140gr projectile at 3550fps, which beats the .264 win man by at least 2-300fps.

Allen Magnum Wildcats

 

[Rizla]

And barrel life is around the 1200 mark so it's not as bad as one might think. I've heard of .243s getting worse than that.

 

[barnesuser28]

The problem is it would be severely over capacity. You reach a point of diminishing returns on such a large case with a relatively small bore. Take a look at the 6.5 STW or the 264 Win... but you are going to have HELL getting a 127gr Barnes LRX with it's G1 of .468 up to the 3750 / 3800 it will take to drive them to 1k and retain the 1600 fps you want...

Love the 6.5, and love barnes copper bullets but you are in for a rough ride sir.
Gary

I live at 2600 ft and i would have to push the 127 grain lrx 3325 fps to hit the 1000 mark with 1600 fps

I am intrigued by the idea of necking down a 7wsm to 6.5 i know it has been done before but i think it would be able to push a 127 grain bullet at 3300 or hopefully a little more. What do you guys think? Should i be able to attain those velocities?

I dont like the .264 winchester because of the belt

 

[barnesuser28]

do you think i could get another 50 fps if i blew out the shoulder to 40 degrees instead of the curret 35 degrees

 

[hammertyme]

Not sure how one would get an efficient powder burn and corresponding velocity fom a Rum case necked down. A long barrel would help for sure.

Stepping a 06 case down to 6.5 with a 40 degree AI type shoulder created pressures before I got the velocities I wanted. On a WSM case it would even be worse.

One could either have a reamer made that moves the shoulder forward and keeps close to the current shoulder angle . Or: I ran the 6.5X270WSM reamer in an extra .050 as well as went in and cut the throat deeper so I could seat the bullet so the base of the 130gr bullet was even with the bottom of the case neck thus all the case capacity could be utilized. I use regular 6.5WSM sizing dies without issue.

I easily get 3100fps from a 19" barrel and Rel 17 or H4831sc

Neal

 

[barnesuser28]

Well i want a beltless cartridge the can push a 127 grain bullet 3350 fps and perferibly in a short action. With running the reamer in an extra .05 wouldnt that cause case head seperation?

 

[hammertyme]

Sorry I forgot

Set a false shoulder when necking down from 270 or 7WSM cases to 6.5.

Bullseye and cream of wheat to fire form the cases to the size of the new chamber.

A 26" Nitrided three groove barrel and you will exceed your desired speed quite easily.
Neal

 

[Rizla]

Not sure how one would get an efficient powder burn and corresponding velocity fom a Rum case necked down. A long barrel would help for sure.

The following is from the Allen Magnum Wildcats webpage which should answer some of your questions. ( Allen Magnum Wildcats )

Recommended Powders: Ramshot Magnum, H-US869, WC-860 and WC-872

Velocity Performance:
Bullet Weight Muzzle Velocity (30" barrel length)
100 gr. 4100 fps
120 gr. 3800 fps
130 gr. 3700 fps
140 gr. (Accubond) 3550 fps
142 gr. 3550 fps

 

[barnesuser28]

Hammertyme could you post some pictures of a 270 wsm compared to your fireformed brass

 

[Michael Eichele]

It's been done already. Kirby Allen necked down a .338 RUM (just a necked up .300 RUM, which is the parent case for the 7mm RUM) to .264. He calls it the 6.5mm Allen Magnum. It can launch a 140gr projectile at 3550fps, which beats the .264 win man by at least 2-300fps.

Allen Magnum Wildcats

Just to clarify so nobody gets a bolt through the head. The 338 RUM and the 7mmRUM and 300 RUM as well as the 375 RUM are not the same case. The 7mm, 300 and 375 are the same case. The 338 RUM is shorter by about 1/10".