257 wby mag - 257 stw - 257 AM

Justin,

What do you want to do with the rifle you are chambering in one of these choices?

These are very different critters, although all 257 caliber, they are basically in different catagories as far as use and performance.

The 257 Wby Mag is by far the most user friendly, also the easiest to load for as it is the least extreme. This chambering is at its best with bullets in the 100-120 gr weight range.

The 257 STW is a dramatic step up in performance but also limits the usible powders for such a large capacity round. If your using bullets of 110 gr and heavier it is a ***** cat to load for with extreme performance. With a 100 gr pill this round will do just over 3900 fps in a 30" barrel, 3850 or so in a 28" barrel.

It will also drive a 130 gr bullet to 3350 to 3450 fps in a 28" or longer barrel.

This round is best suited for bullets in the 115 to 145 gr weights. The 100 gr pill can be used but it is really to light for this big case, the heavier bullets simply work better.

The 257 AM is a monster even compared to the 257 STW. As the designer of the Allen Magnums I am also the first to tell you the weaknesses of these wildcats. Ballistically there are not many except finding a bullet that will survive the severe impact velocities produced by this round, even at extreme range..

Like the 257 STW, the Allen Mag can be loaded with the 100 gr bullets and will top out in the 4000-4100 fps range with a 28" or 30" barrel. Still with such a huge case capacity, these light bullets can be erratic in velocity.

This rounds really starts to run where the STW drops off in bullet weight, starting with the big 130 gr bullets. From here up to the huge 156 gr ULD RBBT is where the 257 Allen Magnum runs extremely hard at long range. With this bullet weight and the velocity potential of this round, it places the 257 AM right there with the largest conventional 7mm magnums on the market. Well, to be honest it is ballistically far superior to them but it is still a 25 cal round which is the reasoning for my comment.

Still, it is an extremely specialized round which is really only suitable for the VERY experienced hand loader. One can only use ball powders, luckily there are a couple that work perfectly that are easy to get. The 257 AM provided legit 1000 yard reach on deer size game but it does have its issues.

It really depends on your goals for the rifle as to which is best for your purpose.

Let us know that and we can give a better recommendation. I am the first to recommend against my own round if it is not the right chambering for what your looking to do.

If your looking for an easy loading high performance deer round, the 257 Wby would be my choice. If you want flatter shooting with still relatively easy loading, I would go with the STW.

If your looking for the ultimate in performance in a 257 chambering, the 257 AM is the tops but it is also the most extreme of all the Allen Magnums and as such the most sensitive to load variation. If you think you know alot about advanced loading of wildcats, the 257 AM may be for you. It will teach you things you never though you would ever need to learn. I say this from personal experience.

There is a reason there are not more 257 AMs out there. She is one wild ride to work with. Once a good load is worked up though, its truely an impressive long range round which makes all the other 257 magnums pale in comparision to her.

Kirby Allen(50)
 
Kirby, to answer your questions, I've been looking at a 25 cal project for a very long time. And yes, I would like something on the extreme end. The reason for this post is because I was talking to the gunsmith who built my .30-338. He has done several stws (257 and 30 cal) and 257 weatherby's. His opinion is that there really isn't anything to gain by moving up to the stw, stating that the 257 weatherby's he has built are pushing the same velocities. I personally find this hard to believe, but I'm not an expert either. Interestingly enough, he told me the 30 stw's that he builds are pushing the same velocities as the 300 RUM with factory ammo, and use 20 grains less powder.
The reason I asked about the 257 AM is simply because I'm curious and maybe just a little envious. In truth, I just wanted to know more about it. As a side note, I'm not and probably never will be a truly experienced person at handloading. I find something that works and stick with it. More or less, I just wanted to know what the differences were between the three, so I can make a slightly more educated decision when the time comes to actually put this project together.

Justin
 
I am not going to say that your gunsmith is wrong because my standard 25-06 is shooting rounds into 257 Weatherby velocities. I am actually exceeding the velocities published in the Hogdon manual of the 257 Weatherby. I am pushing 85/87 gr bullets at 3740 and 100 gr NBT at 3505fps. So in my isolated case I could say that the .25-06 I built (I didn't build but for example) shoots as hot as the 257 Weatherby. An exception like this rarely becomes a rule, so I would advise some caution, and take his words with a grain of salt.
 
Justin,

Well, I personally feel that the comments your smith gave you are not correct. In my opinion and thats all this is, he is giving you simply his opinion. If that makes any sense at all.

I have built several 257 STWs with barrel lengths from 26 up to 30".

I have not built any 257 Wby rifles yet but I have developed loads for several over the years and I will tell you that on average, out of same length barrel, with same bullet weights, with both rounds loaded to top pressures with appropriate powders, the STW will offer a solid 200 fps advantage over the Wby.

This is on average remember, as stated there are rare instances where this is not the case but I have yet to see a 257 Wby get within 150 fps of a properly loaded STW.

I have however heard the same comments you are hearing from guys that say the WBY is getting everything the STW gets and with less powder.

My first question to them is what powders are you using in the STW? They generally say they are using something like RL-22 in both!!

The 257 WBY and STW comparision are like apples and oranges. They are two totally differnet beasts and need to be loaded with totally different componants to get the most out of each round.

When loaded properly the STW will kick the hell out of the WBY in performance but that is not to say its a vastly superior round. Depends on what you want to do with the rifle.

You also need to consider that the larger the case the less the velocity advantage will be with lightweight bullets. I would agree with something like an 85 gr ballistic tip, the Wby would probably run very close to the STW but remember that this is not what the STW is designed to shoot.

I have yet to see a 257 Wby hit a solid 3800 fps with a 100 gr bullet in a 26" barrel. The STW will do this easily.

The main advantage is that as bullet weight increases, the advantage for the larger case capacity increases as well. The heavier the better.

The Allen Mag will give you 200 fps over what the STW will with bullet weights from 100 to 156 gr. I have actually been able to test this first hand. I took my 257 STW with its 30" Lilja and worked up loads with it when it was new.

100 gr..........3945 fps
115 gr..........3710 fps
130 gr..........3455 fps

When I designed the 257 AM, I took that same barrel, set it back and rechambered to the shorter fatter case. This is the results with same bullet weights in same but 1/2" shorter barrel:

100 gr.........4090 fps
115 gr.........3895 fps
130 gr.........3675 fps

Now thats about as fair of a comparision as one can make as its out of the exact same barrel. Both chambers were designed by me with the same specs as far as throat design and body design in the chamber.

Both rounds were also loaded to top pressures. I am not one to shy away from a bit of pressure so I assure you I was getting the most out of each round.

As far as the 30 STW being the full equal to the 300 RUM factory loadings. That may well be. I have chronoed no less then five different lots of 180 gr 300 RUM factory ammo and they all have ranges in average velocity from 3200 to 3250 fps!!!

Yes a 30 STW or 300 Wby or 200 Jarrett will reach this level with top handloads but this is a silly comparision. If you handload the 300 RUM most 26" barreled rifles will push 3400fps with top loads. Compare that to the top loads in a 30 STW and your still 150 fps higher in velocity.

Appearantly it sounds like your smith needs a 300 fps advantage to consider it a meaningful increase.

Again in this case, the heavier the bullet the better the big case does compared to the smaller capacity round.

The only way the above comment from your smith may be true are in very limited instances and in short barrels. On average with barrels in the 26" and longer lengths, this will not be correct.

Just my experience.

Kirby Allen(50)
 
Reloading books are never a factual guide to velocity. Without chrono testing you can't make comparisions.

I totaly agree with Kirby. Once you get into these highly overbore case capacities you have to design the barrel length and twist to take advantage of the heaviest bullets made for that caliber.
 
I have some figures for the WBY mag:
87gr bullet: 3700 FPS
100gr bullet:3500 FPS
117gr bullet:3300 FPS
120gr bullet:3200 FPS
WBY loads them all a 100 FPS faster.
 
Well it looks like the stw is solidly 400 fps over the weatherby. STW brass is plentiful around my place, I'm already loading for a 7mm stw. Has anybody tried the 156 grain bullets in the 257 stw or the weatherby? I know Kirby has tried them in the 257 AM.

Justin
 
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