Advice for rechambering .257 Roberts to AI

[joelweb]

I started handloading a couple years back and finally have dialed the recipe for my go to elk and deer gun. That has me thinking about the other rifles in my safe, especially a Kimber 84 in .257 Roberts.

Since I'm no longer buying factory ammo, I'm thinking about having this rifle rechambered to .257 Roberts Ackley Improved, and I am wondering if folks have advice on how I should go about doing this. I could go down to the local gunsmith and ask them to do it, but I'm wondering if it makes more sense to send the gun to a place that specializes in this type of work. Advice is appreciated.

 

[marksjeep]

There's nothing special about rechambering to an Ackley, any competent smith should be able to do it. Headspace should be reset and is typically a few thousands shorter than the spec for the parent cartridge. SAAMI spec parent cartridge should still fit in the Ackley chamber, but be on the tight side. I fire form new brass only. Fired brass from original chamber has had the shoulder worked already via firing and resizing. Make sure the barrel is in good shape before investing in the work. Sounds like a fun project.

 

[MT_Chad]

plenty of good gunsmiths in western montana that can take care of that. Not sure about the missoula area, I'm sure there are several good ones. Dennis at frontier guns here in helena is very good.

 

[jryoung]

Rechambering is an option, but I've had a few gunsmiths tell me the barrel/grooves harden over time so its best just to rebarrel if you're going to spend money for lathe time.

The next step will be forming brass. Are you going to fire form only, or run them through a case forming die?

 

[buffybr]

I had my .257 Ackley chambered back in 1978. That Ackley reamer is fairly common and any competant gunsmith should be able to do it for you. .257 Roberts brass is getting hard to find.

This has been my favorite rifle for deer and antelope size animals for 40 years. I also used it for all of my wild sheep, a mountain caribou, and one of my best 6x6 bull elk.

My favorite bullets for it are 117 grain Sierra GameKings, 120 gr Hornady HPs, and 115 gr Nosler Ballistic tips. I fireform with full power standard .257 Roberts loads.

 

[joelweb]

Thanks guys. I will go talk to AccuArms in Missoula and see what they have to say. I also get to Helena fairly regularly, so that is an option. This gun doesn't have much mileage on it, and the original barrel is like new. I also have a fair amount of brass, but I haven't put a lot of thought into the forming process yet. Appreciate the bullet advice.

 

[300stw]

i like to set the barrel back one turn before i rechamher them, that way i have complete control over headspace

 

[memtb]

While the “Roberts” is a fine little cartridge......it really shines as an AI! Had a friend with one.....neat round! memtb

 

[mtmuley]

Thanks guys. I will go talk to AccuArms in Missoula and see what they have to say.

I'd call Dan Coffin in Victor. mtmuley

 

[BrentD]

I started handloading a couple years back and finally have dialed the recipe for my go to elk and deer gun. That has me thinking about the other rifles in my safe, especially a Kimber 84 in .257 Roberts.

Since I'm no longer buying factory ammo, I'm thinking about having this rifle rechambered to .257 Roberts Ackley Improved, and I am wondering if folks have advice on how I should go about doing this. I could go down to the local gunsmith and ask them to do it, but I'm wondering if it makes more sense to send the gun to a place that specializes in this type of work. Advice is appreciated.

How many elk/deer do you think you could have killed with an AI that you lost because it was non-AI? Maybe it's not worth it?

 

[HandgunHunter]

Converting a Roberts to an AI is a classic and well worth it.

i would want to make sure they actually set the barrel back one turn before they cut it to an AI.
Many are under the impression that you can just cut it deeper....that’s not the right way to do an AI.
It’s a basic job that any competent gunsmith should be able to do.
while your at it I’d have them bed it and cut a new crown while it’s there.
Many are surprised to see how much bedding and a centered crown can help accuracy.

 

[Seamaster]

You just might be disappointed with the velocity gain after the rechambering if you have a 22" or shorter barrel. It is a lot of fuss and bother (and expense) to rechamber a factory barrel. A good quality aftermarket barrel is a different story.

 

[std7mag]

I have a Ruger 77 MKII in 257 Roberts. Been looking for that particular rifle/cartridge combo that i could afford for years. Finally found one the other year.
Been loading it to +P specs with Hybrid 100V.
Getting more than adequate velocities.
Planning on using it deer hunting next Sat with 115gr Berger VLD Hunting.

Should i run accross another Mauser action i could see an AI in my future.

 

[ImBillT]

The .257 Rob is one of the best cartridges to improve to an AI. It has plenty of body length, and lots of body taper. You get a 9.9% increase in case capacity. Most cartridges doesn’t get such a large increase in capacity due to the parent case having a shorter body and/or less body taper to begin with l. Whenever you get into “over bore” territory, you often won’t realize the velocity gain expected from the case capacity increase, but the .257 AI doesn’t suffer from that the way a .22-250AI, 6mm Rem AI, or .243 AI does. You’ll get the full benefit of the 9.9% increase on capacity. Further more, with many AI’s there is a factory cartridge of similar capacity waiting in the wings that would yield similar results with a lot less fuss. Not so with the .257 Rob AI. There aren’t any common factory .25 cal cartridges with a case capacity of 60gr of H2O. The 25-06 holds 66gr of H2O and because that’s more than the .257” bore can handle well, it yields very little performance advantage over the .257 Rob AI. If you like simplicity and convenience, the 25-06 is still the best .257” cartridge choice, but if you like reloading and being a little different, the .257 Rob AI will do everything the 25-06 will do and both the barrel and the brass will last longer.

Re-chambering a barrel is no more difficult than chambering a new one and involves less lathe time and reamer wear. Still, it’s not significantly less time, so you’re not likely to get a lower quote to re-chamber than to chamber a new barrel, and depending on the price, it’s often most cost effective to simply re-barrel. I get my barrel work free of charge, so I have plenty of things re-chambered and re-crowned. I’ve had many a factory Remington barrel go from 1-MOA to .5-MOA just from being re-chambered.

 

[joelweb]

How many elk/deer do you think you could have killed with an AI that you lost because it was non-AI? Maybe it's not worth it?

I appreciate your perspective, but I'd don't really care about that with this one (within reason, of course). Just looking to enjoy a project and make this gun better.

 

[joelweb]

I'd call Dan Coffin in Victor. mtmuley

Thanks. I'll look him up. Has he done work for you?

 

[joelweb]

Thanks for the insight and advice fellas. You've left me with several things to consider as I pursue this.

 

[mtmuley]

Thanks. I'll look him up. Has he done work for you?

Yep. Good guy and turnaround is acceptable. Built a killer rifle for another HT'er. mtmuley

 

[noharleyyet]

I'd call Dan Coffin in Victor. mtmuley

Dan is the man....

 

[joelweb]

My rifle is now in the hands of Dan Coffin for rechambering. I can't wait to get it back and to start tinkering with loads. Thanks again to everyone for the suggestions.