.264 or 7mm Brass for .257 Weatherby?

[Hondo64d]

I'm going to use either 7mm Rem Mag or .264 Win Mag brass for my .257 Weatherby, and was wondering which one would be preferable.

I've read that either work, but the necks are a little shorter than Weatherby brass. Which one would result in the longest neck? Seems to me that the 7mm probably would, but I don't know if that is necessarily the case.

Another concern is case loss during the initial sizing. When I was running a 25-284, until I started using the seating die,conventional design) as an intermediate step, I was loosing probably 50% of the cases when going from 284 case to 25-284 case. I would like to use my seater as an intermediate sizing step with 7mm brass,if I decide to go with 7mm brass) but now I use Forster's straight line seating dies and don't know if they will support being used in such a manner. If I use .264 brass, I am pretty sure that no intermediate step will be needed.

I guess the only possible advantage to using 7mm brass might be a slightly longer neck, but I don't even know if this is the actual case. Has anyone tried both?

Thanks,

John

 

[fayettefatts]

John:

I've been using 7mm mag brass to form 257 Wby. casings for some time. Sizing has been very easy. I use Imperial Sizing Wax, and size in one step and have had no brass loss. I'm sure 264 mag brass would work as well, but have not tried it myself, mainly because it's harder to find than the 7 mag is.

 

[Hondo64d]

FF,

Thanks for the reply. Got a bag of Winchester 7 mag brass to try. Since I have to size it anyway, it doesn't really matter, but the case necks were in the worst condition of any brass I have ever seen. Probably 30% significantly dented. Anyone else seen this with Winchester brass?

John

 

[Hondo64d]

Just wanted to follow up on this. It's an easy, one-step process, with no lost cases. Runout was pretty horrible, but I am certain the expander on the RCBS dies I used is pulling the neck off center. After fireforming and usinga redding bushing die with no expander, runout is fine.

7 Mag brass is an easy, inexpensive way to produce .257 Weatherby brass.

John

 

[k80skeet]

There is no difference in length between 264Win and 7mm Rem Mag. They are the same Lenght.

 

[AckleymanII]

You guys are really on to something with the 7 Mag Brass.

I used a lot of it, in fact, I took it one step further and sent 3 fire formed cases to Pacific Percision and had Dave Kiff grind a reamer with the shorter necks and also did away with all the freebore.

I had a 257 W that would shoot the 100g Partitions at 3850 out of a 26' barrel and 4000 out of a 30' barrel.

Note: Win 7 mag brass is MUCH tougher than Rem brass, so I used Rem 7 Mag brass.

The necks do get a little thicker at the base, to be the nit picker's nit picker, I turned the brass to clean up the necks.

Accuracy out of the Pac Nor 3 groove ten twist was in the mid to upper twos with three shot groups.

I worked up a load for the 100's in less than 20 shots after sight in with R#22, and found the 100g partitions to be the most accurate partition that I have ever worked with.

Out of the 26' barrel, the 85g Noslers were shooting groups in the low .400's at 4130 fps, and the 85g Nosler Combined Technology bullet is a great deer bullet also.

With a muzzle break on the 'Sendero' weight barrel, I was able to always see the bullet impact on the animal, Deer never take a step.

Drop me an email if you have any questions