WTO 25-7 prc is a ripper

The 257 Weatherby uses a 270 Weatherby case. The 270 is 2.549 in. The 7mm is 2.570.
The 7mm case would give you a few more grains of powder and maybe 100 more fps but I think it is a mute point velocity wise.
Ya beat me to it
7mm, 270, 257 all same case..

257 Weatherby is a basically a 270 or 7mm Weatherby necked down.

Which is what Roy did, he took the 270 and necked it down with no other changes.

So there would be absolutely no gain. I've used 7mm Weatherby and 270 Weatherby Peterson brass to make 257 bee and there was no gain over Norma 257 other than longevity
 
257 weatherby fast twist is bad ***, but honestly I think on the upper edge of what is useful. I have 1.

I know people are shooting 25PRC type rifle nearly as fast as I am pushing mine, and I know mine is loaded on the upper edge of pressure.

I love mine, but if I didn't already have the action, brass, dies, and I wanted a fast 25 cal. 25 PRC would probably be it, built on a long action.

I almost had mine turned into a 264 Weatherby for fun since they never actually made 1, but the 257 is a beast too so I stayed with it.
 
sorry i'm the slow one here ! The 257 Weatherby mag , and the 270 Weatherby Mag ,and the 7mm Weatherby Mag. all share the same case ! so what is different about a 25/ 7mm weatherby! isn't that the same as a 257 Weatherby mag ??? Again. sorry i'm not getting it!!!
 
257 weatherby fast twist is bad ***, but honestly I think on the upper edge of what is useful. I have 1.

I know people are shooting 25PRC type rifle nearly as fast as I am pushing mine, and I know mine is loaded on the upper edge of pressure.

I love mine, but if I didn't already have the action, brass, dies, and I wanted a fast 25 cal. 25 PRC would probably be it, built on a long action.

I almost had mine turned into a 264 Weatherby for fun since they never actually made 1, but the 257 is a beast too so I stayed with it.
the post has gone off track a little bit, but the 257 bee is a great cartridge. But the 25-7prc is faster and more capable with heavy bullets. I have a 7 twist bee that can not come close to the 25-7 prc. I am shooting heavy monos in the bee and it cannot compete speed wise with the 25-7
 
the post has gone off track a little bit, but the 257 bee is a great cartridge. But the 25-7prc is faster and more capable with heavy bullets. I have a 7 twist bee that can not come close to the 25-7 prc. I am shooting heavy monos in the bee and it cannot compete speed wise with the 25-7
Other than FB, what do you attribute that to?
 
Have you tried doing a small ladder to see if you can regain some velocity with more powder? What's your case fill like with N570, probably totally full? You might be able to try US869 to get more powder in the case without getting pressure spikes. Probably be a touch less than your new velocity but might be able to beat the velocity you're getting now by a bit

Us869 is one of my favorite powder for the extreme overbores with heavies. It's very easy on throats relative to basically any VV powder
I have not. My go to load was 70.5 grains of n570 when velocity started falling off with n560. Initially that much 570 got me around 3175 fps with 134's. That same load is about 100fps slower now and not as consistent as it was. It'd take 71+ grains but I want to be done tweaking and just shoot. I have a new barrel coming and I'm going to stay away from 560/570. I'll probably run h1000 next time and hopefully it's consistent around 3050fps. G7 firearms in Utah was using h4831sc in another 20" barrel and getting 3200ish. I'd love that speed but not if it means sub 400 round barrel life. Hopefully with more being built someone finds a combo that's a happy medium between speed and barrel life.
 
So I have been going crazy trying to get these barrels broken in and some development done. I got a 26" prefit for a ARC CDG from Blue Mountain precision, chambered in 25-7 Prc. I have a 25 sst from them as well, that's also amazing. This thing rips, so far just messing around with N570 I got a 3 shot group with an SD or 1 and an ES of 3. I know it's not a thing shooting 3 shot groups but it's the speed that's great. Shooting a 134 from 3330 at 68.4 grains and stopped at 3400 at 70 grains. The 68.4, .7 and 69 had best consistency to work from. All baby groups were around 1/2 maybe a tad under and a tad over.
What is your H2O capacity?
 
Other than FB, what do you attribute that to?
I dunno, I mean I was testing the 134 in the bee and only got 3150 fps before I got pressure. The 25-7 got to 3450 before pressure, but it shoots really good at 3360ish. 200 fps is a lot
 
I dunno, I mean I was testing the 134 in the bee and only got 3150 fps before I got pressure. The 25-7 got to 3450 before pressure, but it shoots really good at 3360ish. 200 fps is a lot
I would think the bee should be faster since it has more powder capacity.

I am shooting 128gr Hammers (really 130gr) 3340fps with H1000. I have the 135gr Bergers running at 3250fps and have not worked that up to see what top velocity is.
 
the post has gone off track a little bit, but the 257 bee is a great cartridge. But the 25-7prc is faster and more capable with heavy bullets. I have a 7 twist bee that can not come close to the 25-7 prc. I am shooting heavy monos in the bee and it cannot compete speed wise with the 25-7
Also, I reading and comprehension skills are lacking. 25-7prc is badass too, but i was thinking about 25-6.5prc. If I eas going to build a 25cal now I would probably use the 25-6.5prc. That seems to be about the sweet spot for performance vs efficiency.

I think when you get to the 7prc or 257 weatherby you have tipped past the point of efficiency and are pushing towards just raw power at the cost of barrel life. If you push past the 7prc and 257 Bee, you are just looking for raw horsepower and speed.
 
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