Is it worth the BS to wildcat?? 257 STW or 257 RUM

[jtoews80]

OK, I've been wanting a wildcat rifle forever and like the .257 & .264 calibers for being fast and delivering a good punch to mid-size game. I really want to build on the RUM case, but is it worth the trouble of getting a custom reamer(with0.375" freebore) & headspace gauge, special order dies w/form dies, resizing new 7mmRUM brass twice, outside neck turning, fireforming the cases to a double radius shoulder to try and preserve barrel life and at the same time possibly using up 50% of it's usable service life.

All this for a .257 cal magnum that will recoil quite heavily, uses significantly more powder vs. some velocity gains over a 257 wby & the performance will most likely only exceed 7mm RUM perfomance with bullets of 115grn weights or less. That is since the parent 7mm fires a 120 grn @ 3670 fps according to the Nosler #6.

Granted, I am a velocity nut. I really like to have the ability to aim almost direct at 400+ yds and know that the bullet will have enough retained energy at the target to ensure a clean, humane kill.

Now I know that the 7mm RUM is overbore and already has a known short barrel life(1000 rnds), but is the weatherby technology (freebore & round shoulders) that makes the 257 wby such a great high velocity round going to prevent this somewhat in a bore that is 0.03" tighter. I want something unique and this wildcat is that, but is there enough advantages to a .257 bore to merit the trouble. Or should I just be satisfied with the already amazing 7mmRUM or a 7mm STW and load down to lower BC projectiles and enjoy a round that is more versitile and alot less original??

 

[buckfever]

The nosler #6 reloading manual shows over 3400 fps with the 115/120 gr bullets and over 3600 fps 100 gr bullets with a 300 yard zero its only 7.4" low at 400 yards that sounds pretty good to me.

 

[JD338]

I don't think its worth the trouble and expense to go with an extream over bore cartridge. For what you want, the 7mmRUM will do it with ease.
If you want a 257 cal, stay with the 257 Wby or 25-06AI. Maybe there is a 257-7mm Rem Mag or AI version that won't be as over bore as on a RUM case. Same can be said with the 257 STW. I'm guessing your barrel life will be in the 800-1000 round life area for a RUM based design.

Pretty much the same for a 6.5mm version of above.

JD338

 

[jtoews80]

The 257 STW, which has about 10-12% less case volume will put out a 100 grn bullet at 3700fps, and 120grns at 3466fps. Not really enough to merit the trouble because one still arrives at the point where in the course of trying to get great velocity great preasures are also created causing throat erosion and much more limited case utilization. The 6.5mm STW and/or a 6.5mm based on a RUM parent case is more versitile offering heavier bullet weights that will get more of the potential energy in the powder turned into kenetic energy in the form of velocity or more mass at the same velocity. Unfortunately, a 0.5mm differance in bullet diameter will not make a noticable differance in ballistics or B.C.'s this side of 800m targets, and basically anything on the other side of 800m is an unethical shot since the average hunter will not practice at that range(IMHO, you shouldn't shoot beyond the range you have practiced at).

This take us back to a 7mm RUM, with the excellent array of bullets availible in 7mm it is not without many great reason that Remington chose to make a .284 round. I suppose if one tried to improve a 7mm RUM with freebore, and round shoulders it may prove worthwhile. Especially since fireformed factory ammo is an option and a mere rechambering is all that is required. Custom dies to reload and then utilize an extra 2-5 grns of case volume made by the wby style shoulders and lowered pressures from freeboring.


Now I like this idea.

Now there is a thought.

 

[rick smith]

Instead of going the 7RUM Improved and having the extra expense it would incur. Add barrel length. A 30" barrel on a 7RUM will probably give very close to the same ballistics as what you are thinking about. and you won't have any other issues to deal with.Rick.

 

[HunterJim]

The .257 Weatherby will deliver to 400 yards without teh drama of building a totally overbore cartridge on the STW or RUM.

You can get into one easily with the Weatherby Vanguard guaranteed accuracy version, or the new Remington M700 with 26" fluted barrel.

It is very hard to justify a wildcat when you have that capability off the shelf (I hunt with a 6.5-'06 too).

jim

 

[JD338]

Instead of going the 7RUM Improved and having the extra expense it would incur. Add barrel length. A 30" barrel on a 7RUM will probably give very close to the same ballistics as what you are thinking about. and you won't have any other issues to deal with.Rick.

+1

Rick,

Again, you have great points!
If you just gota have something different, how about a 7mmRUM AI
......and with a 30" tube.

JD338

 

[cloverleaf]

you guys are beyong my scope of knowledge- but as you know Im a fan of the .25. Have you considered necking down 270 WSM ? From what Ive read that will get you to Wby velocities. Maybe not fast enough for you? But an easy, useable wildcat.

 

[jtoews80]

AS much as I'd love to have a one of a kind custom. I can have a vangauard 257 and a sendero 7mm rum for the cost of building a wildcat on a Reminton action with custom dies, neck turn equipment & brass etc.
And that darn 7 RUm is only about an inch lower at 500yds from a 300 yd zero, somewhere around 5 inches at 800yds. Not alot. The 257 wby isn't really far behind the STW either. not enough to merit custom everything. Someday.

 

[jtoews80]

oh yeah, remington already freebored the 7mmRUM 0.4" which is a touch more than weatherby's 0.375" standard