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-   -   257/300 win mag (http://www.shootersforum.com/wildcat-cartridges/69912-257-300-win-mag.html)

GMFWoodchuck 12-13-2010 05:27 AM

257/300 win mag
 
I was looking at the specs for the 257 weatherby and realized it would be in the same ballpark (Size basic size) as a 264/300 win mag(s) necked down to a 257 bullet. Surely someone has done this.

Any thoughts? Or experience?

fritz1 12-13-2010 05:35 AM

The 264's bullet is already to small to effectively use the case, why would you want to go to even a smaller bullet? If you are going to make a wildcat cartrige why start with a overbored cartrige and make it worst, why not take a overbored cartrige like a 300 ultra mag and neck it up to a 416?, at least the bore would be big enough that you could effectivly use the caes. JMO.

MikeG 12-13-2010 05:52 AM

Pretty much, as I have used 7mm Rem and 300 Win brass to make .257 WBY cases. So, yes, there will be little practical difference. The advantage in the wildcat you describe would be in forming cases.

Use good bullets, it's a fast cartridge. My Vanguard is very accurate. I probably would have never bought one for myself, but I won it in a raffle and it's turned out to be a nice rifle that has taken my two largest deer.

Enjoy......

GMFWoodchuck 12-13-2010 05:52 AM

Fritz1, by your definition then so is the 257 weatherby. However, it reigns supreme in the 257 and under class. And it does well enough in the marketplace despite your reservations about being overbored.

MikeG 12-13-2010 06:03 AM

Oh and if you go this route be prepared (especially with the 300 Win brass) to do neck reaming. I happen to have a Lee Target model loader for the .257 Roberts and I use that to ream case necks after forming.

old roper 12-13-2010 07:57 AM

The 257 Barker Mag is off the 264case they shorten the body gave alittle long neck and at 81gr of powder to get 3500fps with a 120gr bullet. A custom 257Wby with max of 69gr powder give 3400fps appr.

broom_jm 12-13-2010 08:04 AM

The thought that immediately jumped to mind was, why build another belted magnum? If you're going to go this route, neck down a RUM or even a WSM, and ditch the belt. If you want to go nuts, the 375 Ruger is a case that will be necked up and down for decades to come...you might even be the first to squeeze it down to 25 caliber, but heck, even that has probably been done, already.

GMFWoodchuck 12-13-2010 09:32 AM

Why build another unbelted mag? Phfffttt....:)

I didn't actually want one. I just happened to realize the similarity between the 257 weatherby case and the winchester variant case and thought that it would be a total natural progression in wildcatting. I'm not sure if I want to go that route anytime soon anyway. I think for now a 338-06 would be waaay more practical for me. Or even the 264 win mag for that matter.

However if I do want a super fast 25 cal, I think think would be more sensible than even a standard 257 weatherby only on account of cheap brass availibilty.

I guess I'm just ultimately surprised it's not any more common than what it is. And 257 Barker, sounds like it would be the best name for it.

kdub 12-13-2010 09:44 AM

A 257/300 WM smacks pretty closely to a 264 WM. That case would be easier to neck down than the 300 WM and would still be the same case, right?

If you wanted to delete the belt, some .404 Jeffery cases would do the job and eliminate the belt. A 257/404 Would be similar to my present priority factory 7mm Dakota which uses this. Cases cost about a buck and a half apiece, though.

MikeG 12-13-2010 10:14 AM

The shoulder on the .300 is farther forward than the shoulder on either the .264 or 7mm Rem. It does make a difference when forming cases!

old roper 12-13-2010 12:38 PM

Quote:

Originally Posted by GMFWoodchuck (Post 543594)
Why build another unbelted mag? Phfffttt....:)

I didn't actually want one. I just happened to realize the similarity between the 257 weatherby case and the winchester variant case and thought that it would be a total natural progression in wildcatting. I'm not sure if I want to go that route anytime soon anyway. I think for now a 338-06 would be waaay more practical for me. Or even the 264 win mag for that matter.

However if I do want a super fast 25 cal, I think think would be more sensible than even a standard 257 weatherby only on account of cheap brass availibilty.

I guess I'm just ultimately surprised it's not any more common than what it is. And 257 Barker, sounds like it would be the best name for it.


You can take the 257Wby and have the case headspace on the shoulders and elimate the Wby freebore. Depending on barrel used you could use less powder for the same or more velocity.

fritz1 12-13-2010 04:45 PM

Quote:

Originally Posted by GMFWoodchuck (Post 543556)
Fritz1, by your definition then so is the 257 weatherby. However, it reigns supreme in the 257 and under class. And it does well enough in the marketplace despite your reservations about being overbored.

You can take a 25-06 Ackley Improved and do about the same as the Weatherby while burning way less powder, all the while using a 25-06 or 30-06 case and loseing the belted case. All this while also increasing your barrel life too, a way better gun all the way arround.

TMan 12-13-2010 05:01 PM

Quote:

Originally Posted by GMFWoodchuck (Post 543547)
I was looking at the specs for the 257 weatherby and realized it would be in the same ballpark (Size basic size) as a 264/300 win mag(s) necked down to a 257 bullet. Surely someone has done this.

Any thoughts? Or experience?

I did have a .257 X 7mm Magnum for a while. Cases were very easy to form, I used Winchester brass, and I never needed to neck ream. I rarely killed a case. Barrel life was not so much short, but I did shoot it a lot. Performance from a 24" bbrl was pretty much .257 Wby, with cheap brass.

Now, necking the .300WM down, retaining the body length, you have a bit more room than the 7RM or .257 Weatherby. I'm sure there'd be a bit more speed, diminishing returns maybe, but no worse in concept than a 7mm STW.

I think you should go for it, and tell us how it worked :)

fritz1 12-13-2010 05:27 PM

I just looked up the balistics of the 257 Weatherby Mag and the 25-06 Ackley Improved. With both guns shooting a 115gr. Nosler bullet, the 25-06 AI gets 3412fps with 61.5grs. IMR7828. The only way to get over 3400fps with the weatherby with a 115gr. bullet is to load 76grs. of H1000, Hodgdons max load for this powder is only 71grs. so it takes a overload from the Weatherby to equal what the 25-06AI will do with 14.5grs. less powder, a big case that does absolutely nothing. That is the difference in a overbored gun versus a effeciently designed cartrige. Now tell me what 25 caliber truely is supreme.

MikeG 12-13-2010 05:47 PM

Not possible. The bigger case wins, always. The AI data you have isn't pressure tested.

fritz1 12-13-2010 06:14 PM

Quote:

Originally Posted by MikeG (Post 543713)
Not possible. The bigger case wins, always. The AI data you have isn't pressure tested.

Boy are you ever wrong! I can give you several examples of cartriges with smaller cases that outperform the larger case versions. It doesnt matter how big a case you have, you can only put so much pressure in the bore, A big case means you have to use a slow burning powder and alot more powder to create the same pressure as the smaller cased round using a hotter powder and using less in the prosess. Big cases work if you have the bore for it, a small bore builds pressure quicker than a large bore thus requireing a smaller case to do the samething. You can take a 25 caliber bullet and put it on a 50BMG case, you are just going to be burning alot of powder to accomplish nothing because you can only have so much pressure in the gun, case size is only revelant if you have the bore to handle it. You share the same beleifs as most people that dont know any better, "it has a bigger case it must be better". We call this case envie, everone wants a big case to impress the other hunters at camp. Go look at the loadig data on a 270Win and a 264 Win. Mag, the 270 will do anything a 264 mag will do while useing less powder and a smaller case.

broom_jm 12-13-2010 06:43 PM

Fritz,

When a smaller case "outperforms" a larger case, in a smaller caliber, I'm not sure what that proves, but you sorta got it right...the pressure being created is what matters. Where all else is equal (comparing like calibers, pressure levels and bullet weights) case capacity is the determining factor. If you know of some magical formula where a 250 Savage can outperform a 257 Weatherby, I'm all ears.

Mixing and matching calibers to try and argue a point is apples and oranges, even if the bullet weights are the same. If what you're trying to say is that big-jugged magnum cartridges are inefficient, you'll get no argument from me there, but telling someone he's wrong and then giving flawed logic as proof is no way to endear yourself to the members of this forum.

old roper 12-13-2010 06:51 PM

Quote:

Originally Posted by fritz1 (Post 543705)
I just looked up the balistics of the 257 Weatherby Mag and the 25-06 Ackley Improved. With both guns shooting a 115gr. Nosler bullet, the 25-06 AI gets 3412fps with 61.5grs. IMR7828. The only way to get over 3400fps with the weatherby with a 115gr. bullet is to load 76grs. of H1000, Hodgdons max load for this powder is only 71grs. so it takes a overload from the Weatherby to equal what the 25-06AI will do with 14.5grs. less powder, a big case that does absolutely nothing. That is the difference in a overbored gun versus a effeciently designed cartrige. Now tell me what 25 caliber truely is supreme.



Don't get me wrong when I say this but your comparing a factory
chamber rifle to a wildcat chamber.

I have no experience shooting a 25-06AI but Nolser has a max load offor the 25-06 54gr/IMR-7828 with 115gr AB @ 3030fps and that's out of a Wiseman 1/10 twist 24" long barrel. Barnes used the same spec barrel and his top load was 3161fps with 60gr/Magnum 115gr TSX.

Barnes has a load for the 257Wby with 115gr TSX 63gr-68gr/IMR-7828 start velocity 3105fps max 3298fps and one load of max 74gr/H-1000 @ 3383fps. and they use a Wiseman 1/10 twist 24" long barrel. Nolser for the 257Wby use a Lilja 1/10 twist barrel 26" with max of 69gr/IMR7828 with 115gr AB @ 3433fps.

When I decided to build a 25 cal rifle I looked at accuracy/velocity potential of various 25 caliber chambers and I wanted to shoot the 115/120gr bullets. I also wanted a rifle that used factory brass so I settled on the 257Wby and I used a 1/9 twist barrel 24" long brass headspaced on the shoulder OAL 3.250" with no Wby freebore. I'm in the mid 3400fps range using less than a max load from nolser manual with IMR-7828 and 115gr bullets. The barrels marked not for factory ammo.

The 25-06AI you mention is that your rifle if so whats the spec?

fritz1 12-13-2010 06:55 PM

Quote:

Originally Posted by broom_jm (Post 543725)
Fritz,

When a smaller case "outperforms" a larger case, in a smaller caliber, I'm not sure what that proves, but you sorta got it right...the pressure being created is what matters. Where all else is equal (comparing like calibers, pressure levels and bullet weights) case capacity is the determining factor. If you know of some magical formula where a 250 Savage can outperform a 257 Weatherby, I'm all ears.

Mixing and matching calibers to try and argue a point is apples and oranges, even if the bullet weights are the same. If what you're trying to say is that big-jugged magnum cartridges are inefficient, you'll get no argument from me there, but telling someone he's wrong and then giving flawed logic as proof is no way to endear yourself to the members of this forum.

What I was originally saying is you can take a smaller cased 25-06AI with the same bullet, outperform the 257 Weatherby, because the 25 calber bullet cannot utilize the oversized case that it has. It is a innefisent designed that is considered overbored, it accomplishes nothing with that big case that cant be duplicated using a smaller case with a more efficent design, burning way less powder. all that extra powder used in the Weatherby causes throat erosion, shorter barrel life.

fritz1 12-13-2010 08:07 PM

Quote:

Originally Posted by old roper (Post 543731)
Don't get me wrong when I say this but your comparing a factory
chamber rifle to a wildcat chamber.

I have no experience shooting a 25-06AI but Nolser has a max load offor the 25-06 54gr/IMR-7828 with 115gr AB @ 3030fps and that's out of a Wiseman 1/10 twist 24" long barrel. Barnes used the same spec barrel and his top load was 3161fps with 60gr/Magnum 115gr TSX.

Barnes has a load for the 257Wby with 115gr TSX 63gr-68gr/IMR-7828 start velocity 3105fps max 3298fps and one load of max 74gr/H-1000 @ 3383fps. and they use a Wiseman 1/10 twist 24" long barrel. Nolser for the 257Wby use a Lilja 1/10 twist barrel 26" with max of 69gr/IMR7828 with 115gr AB @ 3433fps.

When I decided to build a 25 cal rifle I looked at accuracy/velocity potential of various 25 caliber chambers and I wanted to shoot the 115/120gr bullets. I also wanted a rifle that used factory brass so I settled on the 257Wby and I used a 1/9 twist barrel 24" long brass headspaced on the shoulder OAL 3.250" with no Wby freebore. I'm in the mid 3400fps range using less than a max load from nolser manual with IMR-7828 and 115gr bullets. The barrels marked not for factory ammo.

The 25-06AI you mention is that your rifle if so whats the spec?

It is a Rem. 700 with a 25.25" stainless Shillen barrel with a 1/10 twist. Using Remington nickle plated brass, fire formed to fit the chamber, using CCI large rifle primers, 61.5g of IMR7828, with a nosler 115g. partition, 3412fps, maximum load. Accuracy load 61g. IMR7828 115g bullet is 3378fps


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