Forming .257 Wby Mag - Practical?

[nicholst55]

It appears that if you took .264 Winchester or 7mm Rem Mag brass and tried to form .257 Weatherby, you'd end up with brass about .050" short in the neck, or possibly even more. Short of necking down 7mm Weatherby, is there a practical method of forming .257 Weatherby?

I know that Weatherby brass is available, but it's rather spendy and can be hard to locate. I haven't had spectacular results with it, either. Norma, Hornady and Nosler are the other choices - if you can find it in stock. Hornady is the least expensive of the group, but I've had mixed results with their brass, too.

ETA: I am NOT interested in buying any brass at this time. I've had a couple of offers, which I appreciate, but I am currently almost 8,000 miles away from my rifle, and will be for some time. Not much need for it here in Korea.

[Finster101]

PM sent.

[Elkins45]

I’ve done it. Like you said, 7mm Weatherby is preferable but just as hard to find. Remington sold it in bulk back in the 90s and I wish I had picked up a few more bags.

My experience with forming 7mm Remington is that you really need to anneal the case neck before sizing them. I didn’t do that with my first attempt and I had 100% neck splitting on first firing.

[nicholst55]

I’ve done it. Like you said, 7mm Weatherby is preferable but just as hard to find. Remington sold it in bulk back in the 90s and I wish I had picked up a few more bags.

My experience with forming 7mm Remington is that you really need to anneal the case neck before sizing them. I didn’t do that with my first attempt and I had 100% neck splitting on first firing.

What was the finished length of your brass, if you recall?

[ackleyman]

I had a rifle in 257 weatherby. I hated the cost.

I would urge you to use Winchester 264 Mag or 7 Mag and just run it through the full length sizer, the double radius shoulder will be formed perfectly.

Hint: put a very, very heavy chamfer on the outside of the case mouth and use lube on the neck and shoulder. I NEVER lost a case.

I had a reamer ground with zero freebore and a shorter neck to accomodate the Winchester brand of brass. Remington brass will not hold up, and federal is way too soft.

Good luck!

[15meter]

Never made 257 Weatherby, but I have formed 300 and 375 Weatherby's into 300 H&H's.

Lots of lube, slow going into the sizer die only part way, back out, rotate the case a 1/4 turn, then back in the die a little further, add more lube then keep doing an 1/8" at a time until you've full length resized.

On reform operations like this, I'll make the last pass into the die using a shell holder that has been ground thinner to make sure the case will chamber. First firing will fireform to the correct case shape.

ANNEAL!! After forming the neck will probably be hard enough to split on first firing.

And mount the press as solidly as you can. My bench is a plank bench sandwiched with two 5"x18"x1/2" steel plates. The top plate is mortised into the top and the bench top is tied directly to the 6x6 poles of the pole barn my shop is in. It needs to be that solid to do Weatherby reforming.