Has anyone tried this?

[Fast14riot]

If money for the chambering is a problem, I dont see how you could afford the barrel life of a larger capacity 25 cal. 25x47, 25 creedmoor, or even a 6xc necked up are just about right as far as efficency goes when comparing velocity to powder charge. In my 260AI I shoot 45gr and get 2850fps at the low node with 153.5 bergers. If I went to a 284 or PRC case, I'd still be using several grains more powder to get to their respective low node for 100-150fps more. As much as 10+ grains more to run it hot. Now make a smaller neck and push all that extra flame, heat and powder through it and the throat will be toast in 1000 rounds.

 

[Tangent]

If money for the chambering is a problem, I dont see how you could afford the barrel life of a larger capacity 25 cal. 25x47, 25 creedmoor, or even a 6xc necked up are just about right as far as efficency goes when comparing velocity to powder charge. In my 260AI I shoot 45gr and get 2850fps at the low node with 153.5 bergers. If I went to a 284 or PRC case, I'd still be using several grains more powder to get to their respective low node for 100-150fps more. As much as 10+ grains more to run it hot. Now make a smaller neck and push all that extra flame, heat and powder through it and the throat will be toast in 1000 rounds.

Yes there are diminishing returns. It's not an issue for a hunting rifle but 1,000 round on a target rifle would be a pain. No free lunches. I like the idea of 25cals. I think as a do-it-all rifle they look great. I'll probably end up with a 6GT for shorter range and a 260AI with 153.5 Bergers for the longer range stuff. Now if my wife gets into this game I'd seriously look at a 25x47 or 25 Creedmoor.

 

[DaveTooley]

Only thing better than a 257 Roberts is a 257 Roberts Imp

 

[SKWERLZ]

No one can mention Creedmoor. lol!

Ghey isn’t cool anymore!

 

[longrangehunterII]

Yes there are diminishing returns. It's not an issue for a hunting rifle but 1,000 round on a target rifle would be a pain. No free lunches. I like the idea of 25cals. I think as a do-it-all rifle they look great. I'll probably end up with a 6GT for shorter range and a 260AI with 153.5 Bergers for the longer range stuff. Now if my wife gets into this game I'd seriously look at a 25x47 or 25 Creedmoor.

Any 6.5/.264 is an easy and straightforward choice for necking down to .257. Way easier than taking Lapua 308 W cases to make 7mm-08 that I made over a decade ago. Those necks were turned before being sized down and they came out perfect.

Pick a case and get yourself a SAC Modular die for your parent case. I use imperial sizing wax, it’s so easy you barely know that you’re sizing down brass going from 264 to 257. You won’t even have to turn the necks in this case. Plus you’re sizing the entire neck right down with the proper shoulder position with a SAC Die.

I’ve been shooting the 25x47 for a few years now, and now Alpha has the proper head stamped brass. I use ADG 7 PRC brass for my 25/7 I had Eric @ Blue Mountain Precision build me a lite weight hunting rifle that is another great round. He spun up a 30/06 for it too with
a Serengeti PTG Reamer I gave him. His chambering and bedding jobs are top notch.

Don’t be shy about making what you’re passionate about building! Shoot it until you’re satisfied with what you made, and then you’ll know if it’s a one and done or not.

They’re fairly light recoiling too.

 

[std7mag]

From what I'm reading about what the OP wants, you're best off either necking up 243 Win, or necking down the 260 Rem, trim chamfer and deburr, then fire forming to AI.

I'm using 7X57 Mauser cases for my 257 Roberts and my 257 Roberts AI. Simple one pass through a full length sizing die, then trim and load.

I use my standard Roberts loading (+P) for forming the AI. And I've fire formed while hunting and target shooting.

Keep an eye on eBay for dies.
You can also find interesting stuff at flea markets and yard/garage sales.

 

[10XSHOOTER]

You can run the 6.5 PRC case at 260 AI velocity very nicely with no ill affects and certainly some positive ones.

But you need a Magnum action!

 

[Hoekight]

Has anyone tried necking down a 260 Remington to 25cal and used a 135gr Berger hybrid? Gives equivalent G7 BC to the 6.5mm 144gr hybrid with less recoil. I know 25 Souper, but it just seems easier from a 260 Remington case. A 260AI down to 25cal looks even more interesting...

I have not tried it yet BUT…. My reamer should be here before the end of the week for doing exactly what you are talking about. Took the 308/243/260 case AI’ed it and sent them a bullet seated in a case to set proper free bore for the 135 Berger. I know it’s been done and I know it’s close to a Souper, it’s just my personal spin in it. So for all intents and purpose it’s a 260AI necked down to 25 cal. I have a the components ready waiting on the reamer. I thought about a 25x47 or a creedmoor but finally settled on a 308 case, being I have a ton of brass and it’s also my personal favorite case. I struggled with what brass I was going to use. Necking down 308 brass will require tuning neck twice to get them consistent. Necking up 243 brass would be easiest but that will cause slightly shorter necks. I bought some Peterson 260 srp brass to use. I’ll only have to move it .007.

Had a few laugh at me for doing this but it’s not their time/money and it’s what I wanted. What ever day my reamer shows up it’s getting chambered that day and I’ll start shooting it the next. So I’ll have an update very soon following that. Hopefully by next weekend.

 

[Hoekight]

25/260AI
Chamber barrel. neck down brass and fire form!
trick will be to get dies!

I got 7-08ai dies and changed the bushing.

 

[Tangent]

I have not tried it yet BUT…. My reamer should be here before the end of the week for doing exactly what you are talking about. Took the 308/243/260 case AI’ed it and sent them a bullet seated in a case to set proper free bore for the 135 Berger. I know it’s been done and I know it’s close to a Souper, it’s just my personal spin in it. So for all intents and purpose it’s a 260AI necked down to 25 cal. I have a the components ready waiting on the reamer. I thought about a 25x47 or a creedmoor but finally settled on a 308 case, being I have a ton of brass and it’s also my personal favorite case. I struggled with what brass I was going to use. Necking down 308 brass will require tuning neck twice to get them consistent. Necking up 243 brass would be easiest but that will cause slightly shorter necks. I bought some Peterson 260 srp brass to use. I’ll only have to move it .007.

Had a few laugh at me for doing this but it’s not their time/money and it’s what I wanted. What ever day my reamer shows up it’s getting chambered that day and I’ll start shooting it the next. So I’ll have an update very soon following that. Hopefully by next weekend.
View attachment 1716761

I knew someone on here would have tried it or, in your case, is about to. I will be watching with great interest to see how you get on. Sometimes it's not whether you should, but if you could. The 308 case makes a lot of sense, so many of its variants around and all of them shoot so well.

I expect it will shoot really well with good velocity too.

 

[Darkside]

I have not tried it yet BUT…. My reamer should be here before the end of the week for doing exactly what you are talking about. Took the 308/243/260 case AI’ed it and sent them a bullet seated in a case to set proper free bore for the 135 Berger. I know it’s been done and I know it’s close to a Souper, it’s just my personal spin in it. So for all intents and purpose it’s a 260AI necked down to 25 cal. I have a the components ready waiting on the reamer. I thought about a 25x47 or a creedmoor but finally settled on a 308 case, being I have a ton of brass and it’s also my personal favorite case. I struggled with what brass I was going to use. Necking down 308 brass will require tuning neck twice to get them consistent. Necking up 243 brass would be easiest but that will cause slightly shorter necks. I bought some Peterson 260 srp brass to use. I’ll only have to move it .007.

Had a few laugh at me for doing this but it’s not their time/money and it’s what I wanted. What ever day my reamer shows up it’s getting chambered that day and I’ll start shooting it the next. So I’ll have an update very soon following that. Hopefully by next weekend.
View attachment 1716761

What he’s doing.
Yes it has been done and works very well. The person that made a comment about 35&40 degree shoulders not working/ you need to find a new gunsmith. Bushing dies in a 260ai works great. There’s a few die makers that make them.
If you want to build it then build it .
I’m working on necking down the
277 Fury to 257/25, maybe next year.
Let’s hear the Bashing of the Fury

 

[Hoekight]

I knew someone on here would have tried it or, in your case, is about to. I will be watching with great interest to see how you get on. Sometimes it's not whether you should, but if you could. The 308 case makes a lot of sense, so many of its variants around and all of them shoot so well.

I expect it will shoot really well with good velocity too.

I’m hoping and praying I can get it to 2900-2950 with accuracy. I think it will but it might take playing with powder combos to do it. But either way I’m gonna know here in a few days

 

[Hoekight]

What he’s doing.
Yes it has been done and works very well. The person that made a comment about 35&40 degree shoulders not working/ you need to find a new gunsmith. Bushing dies in a 260ai works great. There’s a few die makers that make them.
If you want to build it then build it .
I’m working on necking down the
277 Fury to 257/25, maybe next year.
Let’s hear the Bashing of the Fury

I found a set of new 7mm-08ai bushing dies. I think they will work. If not I’ll back up and punt and try to get 260ai dies or get a custom set cut.

 

[NZ_Fclass]

It was kicking around a while ago as the 25 Souper ( may have been 243 brass - but certainly a 308 family case). A good mate thought about it, then built a 25 Roberts AI - which I now own.

.25-08 (.25 Souper)

 

[muleystalker]

But you need a Magnum action!

Yes.... I think I stated that in my comments. But a bolt can be opened up, in some cases just a new bolt head or a bolt. It can be a lot cheaper sometimes than trying to solve a bunch of other problems like a bunch of dies to form brass along with time, having a custom reamer made etc.

 

[Darkside]

I found a set of new 7mm-08ai bushing dies. I think they will work. If not I’ll back up and punt and try to get 260ai dies or get a custom set cut.

The 7-08Ai will work.

 

[Fast14riot]

I found a set of new 7mm-08ai bushing dies. I think they will work. If not I’ll back up and punt and try to get 260ai dies or get a custom set cut.

There was a 260AI FL type S die for sale in the classifieds not long ago. I don't know if it sold yet.