View Full Version : 2506 to a 257IA

April 22, 2011, 11:58 AM
Can a Winchester model 70 in 25/06 be rechambered to a 257 Roberts AI? Is the excisting chamber to long already? Will the bolt head work being the 257 parent case is a 7x57?

April 22, 2011, 12:23 PM
I would go to a 25-06 AI first, more to gain. but if the 257AI is what you want, just look at the cartridge drawings first. The case length's are 257AI 2.23 inch and the 25-06 2.49 inch the difference is .26 inch just over a quarter inch that's the minium setback the gunsmith woud set the barrel back.

Basicly your going backwards with the 257AI.

April 22, 2011, 12:24 PM
The .25-06 case is longer than the .257 Roberts (and the AI version). If this was to be done the barrel would also have to be set back the appropriate distance.

The bolt head is the same for both cartridges.

April 22, 2011, 07:25 PM
Wouldn't that be kind of like removing a 4 barrel carb and replacing it with a 2 barrel

April 23, 2011, 10:17 AM
I would say with todays modern powders the 25-06 is nolonger considered overbore.

You have to deal with a short cartridge in a long action, so feeding problems might come up.

April 23, 2011, 02:17 PM
I have not done this,but I do have a .257 AI and I own a M-70.I believe if you had a .257 Roberts M-70,it would differ from the 25-06 M-70 in the following ways:
A blocked forward mag box
A shorter follower
The extractor collar on the bolt would have a block on it to limit rearward travel of the bolt
The ejector/bolt stop parts may be slightly different.
I know this from investigating lengthening the mag box on my 7 mag M-70 to put VLD bullets closer to the rifling.
These parts are not easy to find.
Now,regarding your decision,I built my 257 AI on a Mex 98 Mauser.Its a shorter small ring 98 that was originally a 7x57.The action is sized to the cartridge.Its a nice match.
You are about to spend time and money to keep a long action but make it work with a shorter cartridge that is the same performance.
You also now have to fireform brass.Think,burning powder and bullets,and subjecting the bbl to more wear.Are you going to fireform 500?
If I lost my .257 AI,I might replace it with a 25-06.Its easier.

April 23, 2011, 02:35 PM
I think I will just go with a 257 and use +P loads and play with handloads. Hodgdon powder list some hot loads for the 257R at 46K cup and the +P is capable of 50k cup.

April 23, 2011, 03:52 PM
What caliber rifle do you have a 257 Roberts or a 25-06?

Your first question was about going from a 25-06 to a 257.:confused:

April 24, 2011, 12:39 PM
Could he be Richard Cranium ???

April 24, 2011, 01:06 PM
Wouldn't that be kind of like removing a 4 barrel carb and replacing it with a 2 barrel

No. It's more like sleeving your engine block to reduce displacement from 454 cubic inches to 396 cubic inches. Or... Cutting 2 cylinders off your V8 to make it a 'more efficient' V6.

Some people just don't like the .25-06, and plenty of people like shooting wildcats or semi-wildcats.

Either way, the .257 Roberts is a fine cartridge. The little bit of extra velocity attainable in the improved versions is nice, but not required.

April 24, 2011, 02:38 PM
kind of off topic here, kinda. First, I do very much like the .25-06. However it is an overbore cartridge and is prone to accellerated throat erosion. The
.257 Roberts is about ideal case capacity to bore dia. and does not suffer the same as the .25-06. The advantage the .25-06 has is realized when you get to the heavier bullets. More powder capacity moves those heavy bullets faster than the .257 Roberts. Yes the .25-06 will shoot faster and flatter but at a cost and is not necessarily more accurate. I do like the .257 Roberts but I have 2 .25-06's. Just my $.02.

April 26, 2011, 11:29 AM
Your better to rebarrel the rifle, but you may run into feed problems since the 2506 uses a "long" action the 257 uses a "medium" action. I will say that despite being a big fan of Ackley, many of the AI conversions are not worth the trouble, the perceived performance increase just isn't there considering what modern bullets and propellants can do these days not to mention the fact that when the AI's were being developed there was not such a wide range of caliber choices as we have today that can match and in many case outmatch the AI. I have several including the most efficient ones .280AI, 30-30AI, 22-250AI and the most efficient of them all...which many have never heard of, the .30AI. I suggest if you are going to rebarrel, look into a more efficient bullet as well like something in the 6.5mm size

April 26, 2011, 11:34 AM
You mention the long action compaired to an intermediate one but I emailed Ruger and they put their 257R on a long action, but I understand your point.

April 26, 2011, 01:31 PM
You mention the long action compaired to an intermediate one but I emailed Ruger and they put their 257R on a long action

Yea, they just block the magazine well. Intermediate cartridges in long actions isn't a big deal.