257-7mm rem mag

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7 REM MAG

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hey all, i was just wondering if anyone out there is necking down the 7 rem mag or 264 win mag to 257? anyone with experience doing this or reports from buddies doing it? seems like it would be a good way to get 257 wby performance in an affordable rifle with endless supply of cheap brass.
thx all
 
7 REM MAG said:
hey all, i was just wondering if anyone out there is necking down the 7 rem mag or 264 win mag to 257? anyone with experience doing this or reports from buddies doing it? seems like it would be a good way to get 257 wby performance in an affordable rifle with endless supply of cheap brass.
thx all
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Why do that ?--just run new 7mm Rem Mag cases in your 257 W.M. die and you have 257 W.M. cases--a tad short but could not matter less----Bent Barrel
 
I have both a 257 weatherby and a 25-06 and my weatherby uses 7mm rem mag brass like bent barrel said because I'm cheap. Now if you want 257 weatherby performance for cheap just buy a 25-06. You will find that the 25-06 will get you within 50 fps with 12 grains less powder. A 257 weatherby is really a waste of powder but the name means a lot to some people.
 
billdick said:
I have both a 257 weatherby and a 25-06 and my weatherby uses 7mm rem mag brass like bent barrel said because I'm cheap. Now if you want 257 weatherby performance for cheap just buy a 25-06. You will find that the 25-06 will get you within 50 fps with 12 grains less powder. A 257 weatherby is really a waste of powder but the name means a lot to some people.
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I have both and Ive never got within 50 fps of my 257 wby with any load from my 25-06. But like u said if some one wants cheap, the 25-06 will do the same job
 
7 REM MAG said:
hey all, i was just wondering if anyone out there is necking down the 7 rem mag or 264 win mag to 257? anyone with experience doing this or reports from buddies doing it? seems like it would be a good way to get 257 wby performance in an affordable rifle with endless supply of cheap brass.
thx all
Click to expand...
I have often thought it was an excellent idea. I asked about it on 24hr but there wasn't much info on it. Virtually the same capacity as the regular 257 bee, but no double radius or short neck (when you resize 7rm to 257bee). If you decide to build one, let me know and perhaps we can split costs.
 
This thread got my noodle straining. Thinking of the various parent cases, necked to .257. While we are gun nutz and need no reason beyond that.....i still really dont see the point. The .257 Bob is off a 7x57...basically same capacity as a 308....so. Then the 25-06 off a 30-06 case, and if i remember correctly the 257 Wea is also based on a 30-06 case ...not the H&H that the larger Wea are based on....simply with the Wea shoulder....a 25-06 AI except a Wea. Off the top of my head i cant recall the difference in capacity between a 30-06 and a 7 RM case, but it is not a lot.

In owning a bunch of Rum calibers, one comes up against one fact. No matter how big the case, you can only push so much power through a little hole. For the Rum calibers the tipping point seems to be 7mm Rum. Any attempt to go to smaller Rum calibers results in gigantic throat erosion, super short barrel life, and insignificant increases in speed, over existing calibers in those bores. Someone else has already pointed out the 257 Wea uses 12 grains more and only gives 50 ft/sec more than a 25-06...think there was a difference of 2" in barrel which should account for about 100 Ft/sec. It would seem that the 25-06/257 Wea is hitting this same reality the wildcat Rums encounter.

I just think that you are beating your head against a ballistic wall, trying to get more speed out of 257 bore, that is not already accomplished by existing calibers. Adding a longer barrel might accomplish as much. Then considering game performance, if one tried VLD or other frangible bullets to perform on game as the pill drops below supersonic at longer ranges.....yes the bullet might fragment or expand...but it is a 120 gr bullet. Even 6.5 with 140 gr bullets are limited against large game because of the mass of the projectile.

Like i said it gets the noodle cooking.
 
The case capacity of the 25-06 is 65 grains of water. The case capacity of the .257 Weatherby is 85.6 grains and it is based on the magnum case. That works out to about 32% more, and the standard rule of thumb is that with powder optimized velocity increases by about 1/4 of the increase in case capacity. I know my .257 Weatherbys are faster than my 25-06 and I don't care about the extra bit of powder burnt. It comes out to 4 cents extra per shell. Recoil is bugger all in either case.
 
Ya my bad. I think its the 240 Wea that is based on the 30-06....the others are blown out 300 H&H.

Only ever had one Weatherby, a 300 years ago. How are guys finding barrel life of say a 300 Wea?? I know that a optomistic life for a 7 Rum is 800, and some start to degrade much sooner. Would this proposed 257-7RM be a barrel burner??
 
it wouldn't be anymore of a barrel burner than the 257bee. the idea was to have a semi custom, in a nice medium rifle chambering thats easyish to feed with cheap brass. seems like just neck sizing down 264 win mag would be pretty easy, wouldn't have to fire form brass like you would have to if making 257 bee brass. and you would have something different than anyone else out there. thinking a new model 700 long range in 25-06, rechambered to 25-7mm rem or what ever you wanna call it, open up the bolt face with a sako style extractor and true the action. semi custom with a 26" barrel, cheap brass and probably not the worst way to spend 2k. guess you could just go with 257 weatherby but its fun being a little different every now and then
 
You can buy Weatherby brand .257 'Bee factory ammo for 42 bucks a box. That's cheaper than buying the empty brass, and sort of takes the fun out of spending 2 grand to use cheap brass.

If you wanted either a .257/7mm or a .257 Weatherby on a long range you would be farther ahead buying a 7mm or .300 Win and rebarrelling. Opening up the bolt-face on doing a Sako extractor is a 300 dollar touch if I remember right and that goes a long ways toward buying a new custom blank. Its easier to get a good chamber on a new blank than a rechamber, and the odds are custom barrel is going to out-shoot a factory barrel.

Are you prepared to buy a custom reamer and probably custom dies to shoot your wildcat with "cheap brass"? You can buy a lot of expensive brass for what that will cost you.
 
7 rem mag, If you are serious - let me know. I would gladly split the reamer cost and a set of dies isn't the end of the world - contrary to what some believe.
 
I could not find .257 Wby brass for a long time. I did re-size 7mm RM brass to .257 Wby.
It worked well, but the necks had to be outside-turned afterwards due to thickness. I turned the necks down to 0.013" thickness. If you're going to do it, anneal the necks first. I lost a couple of cases due to wrinkles and 1 split.

The cases end up a bit short, but not a problem.
I now have a bunch of Hornady .257 Wby brass, so my 7mmRM/.257 Wby brass is sitting in a box on the shelf.
 
thats a very good point dogleg, magnum action and rebarrel would likely be there better route, and yes i know the costs associated with building a not common rifle, not my first time at this rodeo. double gun ill send you a pm.
 
I have several hundred 257 Wby cases all made from W-W 264 WM and I wouldn't have it any other way. Using 264 brass eliminates the need to thin necks and there really is no special fire forming required. Just run 'em through the die and load..........I have both the 25-06 and the 257 Roy, as well as the 257 Bob and the 250-3000 (Savage), and I can tell you the Bee has no peers in this group. I get 3600+ fps with 110 gn ABs using RL 25 and have several loads on these cases. I actually backed down from over 3700 fps to my current load, for accuracy and case life. This is still 300 fps faster than the hottest load in a 25-06.
As Dan pointed out, the 25 Ackley Magnum has been around since the 40s and there are no mysteries about it, it won't do anything that the Bee won't do and may not even match the Bee. The radius shoulder is not a gimmick and does work, I have proven it myself, so I think your efforts and dollars may be better spent elsewhere. And don't forget this is coming from a devout wildcatter...........may I suggest a 25-300WM instead, that may go somewhere interesting.........or possibly a 25 WSM, not the junk WSSM just a 270 WSM necked down to 25 cal, again that may be interesting. Another really cool and interesting cartridge is the 25-300 Wby..................Just giving you something to ponder. If all you want is a 2 1/2" belted 25, then you will not improve on the 257 Wby in any area.........so why bother?
 
I've made a lot of .257 Weatherbys out of 7mm Rem mag. It works best with new brass. Just a little smear of Imperial sizing die wax and a single trip through the .257 FL die. The Weatherby shoulder even rounds out; perhaps not exactly perfectly but you'd have to stare at it awhile to notice. Run-out on the reformed cases is less than new Weatherby brass out of the box. Most of my son's loads are in the Winchester brass and mine are in the Weatherby and Norma headstamp cases. It helps keep them straight if individual shells start migrating.
 
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