257 stw

[keeki]

help me out guys. i know nothing about big magnum cases so what is the difference between 7rem mag and 8 rem mag cases other than the neck?

[leather5to1]

There is a pretty big length difference. About the same as a 300 weatherby to a 7mm weatherby (almost a half an inch). The 7mm stw is the 8mm rem mag necked down, a 257 stw is going to be a powder hog, now and then I shoot a 6.5 wwh which is a 300 weatherby necked to 6.5. That uses a lot of powder and likes to get barrels hot so I think you are in for a barrel burner.

[keeki]

ok, i see where i misread. its the 7mm stw case and the 8rem mag case

[Blackwell bikes]

There is no major length differences as The STW's are based on the 8mm rem mag. Has for the 7mm rem/308 Norma sized cartridges the STW's are quite a bit bigger

2.5 case length for the 7mm Remington mag

2.85 case length for 8mm rem mag

2.85 case for the 7mm STW

[GaCop]

STW calibers are fantastic long range game cartridges but REAL barrel burners.

[Potsy]

I read Layne Simpson's original article in "Shooting Times" on the .257 STW the other day.
I think it was from about '98.
He was getting from 3700-3800fps from 100 grain Ballistic Tips out of 26" barrels.
While the article came with a whole page of reloading data, he never mentioned whether any of it had been pressure tested.
Kinda had to wonder if the same fate awaited the .257 that came to the 7mm STW; when somebody bothered to pressure test it, it wound up doing nothing a regular 7mm Rem Mag. wouldn't do (not trying to start a fight, just based that on the data I see).
I'd love to hear a little more input on this, cause it'd be one more killer if it could perform as advertised back then.

[leather5to1]

The funny thing about the stw is that it isn't anything new. The 7x300 weatherby was setting records on the 1000 yard ranges in the 70s. The 7mm stw has only a couple of minor differences to the neck and shoulder. But yup a lot of barrel burning going on there.

[Harry Pope]

...Kinda had to wonder if the same fate awaited the .257 that came to the 7mm STW; when somebody bothered to pressure test it, it wound up doing nothing a regular 7mm Rem Mag. wouldn't do (not trying to start a fight, just based that on the data I see).

I'm not sure where you "saw" that "data" but published pressure tested data is plentiful. The 7mm STW exhibits just the velocity increase you'd expect for the case capacity increase - 100 to 200 fps - with the most useful bullet weights.

Hornady:
7mmRem
154@3000 fps/3078 fpe
7mmSTW
154@3200 fps/3503 fpe

Speer:
7mmRem
160@3012/3224
7mmSTW
160@3133/3488

Sierra:
7mmRem
160@3100/3415
7mmSTW
160@3250/3754

Lyman:
7mmRem
160@2933/3057
7mmSTW
160@3170/3571

To some folks 150 fps is a big difference. To others it is nothing.

[Potsy]

I know there's plenty of good pressure tested data on the 7 STW now, I was wondering if there was any on the .257 STW.
The only reference I've got on front of me (I've got other stuff buried) is the '09 Hogdon manual.
Data in it lists a 160grn SFT SP (I'm assuming Swift Soft Point?) topping out at 3085fps for the 7 STW.
It lists a 7mm Rem Mag as pushing a 160 Nosler Partition at 2915.
Granted, the Hogdon manual is a little handicapped by listing 2 different bullets (apples to oranges) and it handicaps both rounds (especially the STW) with 24" barrels.
So, yes, it'll best a 7mm Rem. Mag by 150fps or a little better.
When the 7 STW was introduced, there was a lot of data flying around for 140's in the 3400-3450 range (I've got one of the original Shooting Times articles on it laying around somewhere, can't find it at the moment). Current Hogdon data for a 145 SPR SP (Speer Soft Point?) tops out at 3209fps.

I was just wondering if anyone (be it a powder company or at least somebody with a strain guage) had developed pressure tested .257 STW loads to see if it would give the gains they thought it would (100 grainers @ 3700-3800) when it was introduced.