257 Wby Mag Cartridge forming

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notenough

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Just looking to see if anyone here has some experience forming 257 Wby Mag brass from 300 Wby Mag brass or 300 H&H brass.

I know about the 7mm Rem Mag but I have one of those as well and don't want to mix the brass.

I do have some 7mm Wby Mag brass that forms very nicely but not enough of it.

I just figured that since I have 100 300 Wby Mag brass and 30 300 H&H brass I could convert them to 257 WBY Mag brass with a little time and effort. Not a big fan of $40-$50 for 20 empty cases.

I also already have the case neck turner as well.

I'm thinking about resizing in a 300WM first and keep going in a 308 sizer until I'm at the 257 length. Once that is done to start the necking down process. This would all be done after an initial trim.
 
Why do U want to do this. U can't change the stamp on the head of the case U want to use, this sets u up for a very dangerous situation. Head of casing says it is one cal. but is made to fit another. The cost of buying new unprimed casings isn't worth the chance of making a mistake and blowing your gun up or killing yourself.

I have been reloading for 30 plus years and in My mind this is just stupid. Sorry for being rude, but think about it.

Just spent the money and save your life.
 
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What kind of .300 Weatherby brass do you have, and are they once fired or new? It shouldn't be that hard to sell them.
Why the concern over making cases out of 7mm Rem Mag? The cartridges don't look alike, and you wouldn't be able to chamber a 7 Rem Mag in the .257 if you tried. Apparantly the wrong headstamp on the cases doesn't bother you, so why not a different brand of 7mm cases?
 
PAPA BEAR said:
Why do U want to do this. U can't change the stamp on the head of the case U want to use, this sets u up for a very dangerous situation. Head of casing says it is one cal. but is made to fit another. The cost of buying new unprimed casings isn't worth the chance of making a mistake and blowing your gun up or killing yourself.

I have been reloading for 30 plus years and in My mind this is just stupid. Sorry for being rude, but think about it.

Just spent the money and save your life.
Click to expand...

You shouldn't be shooting anyone's hand loads anyway. And to boot I don't own a 7mm rem, so you see there is no danger. That brass works fine in my rifle, Weatherby ammo looks allot different. And you would have to a retard to load .257 wby formed rounds into a 7mm rem.
 
Brass

First off, all my 7mm RM brass is taken, Rem used for target, Win for hunting, Fed for other bullets such as practice.

As for converting the 7mm Wby Mag, 300 Wby Mag and 300 H&H, it's simply because I don't have rifles for those calibers so I'm not worried about the head stamp. When I pass away my reloading data information will show what the head stamps are for. So will the box that holds the ammo.

As for buying new brass, try and find some. It's not totally impossible but I have this other brass and I need 257 Wby Mag brass, simple.

Cartridge conversions are done all the time, I've already completed a straight forward one in an 8mm-06 A.I. for a K98 Mauser.

I don't see the 257 Wby Mag conversion being any more dangerous than any other cartridge. Probably safer since the Weatherby has the same three rings of steel as Remington and has 3 gas ports in the bolt if you do have a problem.

Thanks for the comments so far guy's but nothing listed so far is very helpful!
 
Size

What I'm looking more for are tips on sizing down. Going stright from a 300 to 257 will cause dents and cracks in the case neck, shoulder and/or mouth.

I'm aware I'll need to lube the expander ball and heavily lube the inside case mouth.

I was just looking to see if anyone else has done this work and if they had any tips on completing it with the least amount of garbage brass.
 
No you can not form 300 Wby Mag brass or 300 H&H brass into .257wby those are large magnums like the RUM while the .257wby is a standard magnum. The 300 case is not only longer it is .4949" at the shoulder. All the smaller Wby's are 2.549" long and .4921" .
 
Parent Case

What I was looking at was the fact that the 300 H&H is the parent case for the 300 Wby Mag. The 300 Wby Mag was also the parent case for the 257, 270 and 7mm Wby mag's just as a shorter case. So somehow they managed to make the shorter mag out of the longer case at one point.
 
wiki is your friend

The .257 Weatherby Magnum was introduced as a wildcat during the mid 1940s when Roy Weatherby was building custom rifles around war surplus '03 Springfield and the '98 Mauser actions. It was always his favorite cartridge.

The .257 Weatherby Magnum cartridge case itself a shortened version of the .300 H&H Magnum case necked down to .257 caliber and blown out the full length of the case which then sports a double radius shoulder and shortened to 2.545" with a long neck.

srt4u2nv said:
No you can not form 300 Wby Mag brass or 300 H&H brass into .257wby those are large magnums like the RUM while the .257wby is a standard magnum. The 300 case is not only longer it is .4949" at the shoulder. All the smaller Wby's are 2.549" long and .4921" .
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Your point? Are you just reaffirming what I posted?.... its a heck of a lot of work to make .257 brass out of 300h&h when you can pass 7mm mag brass through the die once and your good to go.
 
It wasn't a question of how much work. Just that you said it couldn't be done

srt4u2nv said:
No you can not form 300 Wby Mag brass or 300 H&H brass into .257wby those are large magnums like the RUM while the .257wby is a standard magnum. The 300 case is not only longer it is .4949" at the shoulder. All the smaller Wby's are 2.549" long and .4921" .
Click to expand...

BTW WSS shows bulk bags of 50 264Winny Mag for 45$
 
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teenahlake said:
It wasn't a question of how much work. Just that you said it couldn't be done

BTW WSS shows bulk bags of 50 264Winny Mag for 45$
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It can't be done with out an enormous amount of work and investment in equipment you simply can not form .257wby brass out of 300H&H......Have you tried? do you own a .257 wby?....I do and I load for other guys who have .257's too and let me tell you some times even 7mm mag brass is a pain to use....With the investment in equipment to turn 300H&H into .257wby its makes it a loosing investment just buy 7mm mag or like you pointed out .264 win mag.

Maybe I was wrong you can make .257wby brass out of .300H&H but is it worth the time and money?...NO.....
 
notenough said:
What I'm looking more for are tips on sizing down. Going stright from a 300 to 257 will cause dents and cracks in the case neck, shoulder and/or mouth.

I'm aware I'll need to lube the expander ball and heavily lube the inside case mouth.

I was just looking to see if anyone else has done this work and if they had any tips on completing it with the least amount of garbage brass.
Click to expand...

I've gone from 303 British to a .22 wildcat with only one "in between" step: Just used a 7mm die with the expander plug removed, and made sure the cases were well lubricated. Kinda 'worked' the brass into the 7mm and 220 Swift dies...in a bit, back off, in a bit more 'til done. Lost 2 or 3 cases out of 60.

As far as "the wrong head stamp" goes what's the worry? There's no way anyone could close the bolt on the 257 Wby. with a .264 or bigger case, and if someone stuck the 257 cartridge in a longer chamber so what? Worst that could happen would be a lost animal, and it would run away laughing.:D

Fireform the brass in the 257 chamber and then neck size only for subsequent loadings. Good practice with belted cases anyway....
 
IF YOU HAVE TO DO it
#1 Find a 308 Norma Mag Die remove expander ball and decapper assembly
Use the Norma die it to bump the shoulder back to the 257 shoulder
#2 At this stage I would trim to approximate length and anneal
#3 run into 7mil W and then into 257 W with expanders removed
#4 Turn case necks
#5 resemble 257 W die and resize.
#6 Trim to final length
You will have perfectly formed 257 Roy ready to load.
Opinions will vary but this method I Know will work.
#7 After thinking about this for a while try a couple and if they give trouble anneal first

Rich
 
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notenough,
PM me with your mailing address and I'll lend :)you a 308 Norma FL die if you don't have one already. It may not be essential, but there should be less risk of buckling the shoulder this way.
 
Don't even bother trying to make cases from the 300H&H or 300Wby. Just use 7mmRM or 264 WM. Not worth the trouble IMHO. I will swap you some 264 brass for the 300 if you want.
 
Cr#p

Well I'm wondering if anyone else has run into this type of problem. I pickedup some 264 Win Mag brass to convert to 257 Wby Mag. One swipe through my RCBS FL sizer and I was done. Finally got my rifle and loaded up my first round and it would fit but it was tight, I figured it just needed to be properly fireformed. Tried out the second round and the same thing so I loaded the other 28 test rounds. Befor heading to the range I decided to check the number of rounds this gun would hold and noticed that the other 28 rounds I made will not chamber. All the Weatherby brass I have in 257 or converted 7mm Wby works just fine. It's just the 264 Win Mag brass does not fit. I even tried resizing a few peices several times and nothing is working.

Derek
 
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