.257 Bob Improved?

V

Vartarg217

New member
I just bought a Kimber model 84 Montana in .257 Roberts. There's another "Bob" thread going right now....but doesn't address my question, and I didn't want to hijack that thread.....not fair to the OP.

The rifle is at my gunsmiths, and because of travel plans I won't be able to pick it up for a couple of weeks. I've been thinking about having him ream it to a .257R AI.

I've searched on the PM search engine, and studied the Hodgdon reload data on specific bullets and powders, and it doesn't appear to me to be worth while.

From what I can tell, it seems that I might pick up anywhere from 100 to 150 fps, and in many cases less....but maybe I'm missing something here?

I'll be using the rifle for hogs and coyotes, and am reluctant to make it an AI....

Comments or experiences you'd like to share?

Thanks
 
I had always heard that the bob was one of the few that PO himself actually thought was a significant improvement. Guess it depends on what you consider improvement.
 
Vartarg...IMO...P.O Ackley said that the .257 Roberts IS ONE of the most succesful A.I rounds he's ever made. Just Google .257 Roberts Ackley Improved. There is hundreds of pages on this round. I have a Mauser 98 chambered in the .257 Rob. Not an A.I. But, for ME I really LIKE this round. Have shot several deer, and coyotes. I'm using a 87 grain soft point Speer I think. Anything inside 300 Yards put the cross on it and squeeze. There is very little aiming HIGH at that range. Good Luck you will enjoy that rifle for sure..Also, you will gain fps. I have shot this rifle and I reload for it also. Very little case stretch. But there will be even less with the Ackley Imp. because of the straighter wall case. And a little more powder also..Good Luck
 
I am a fan of both the 257 Roberts and the 257 Roberts AI. The big advantage with the AI cartridge is that you can shoot the heavier ~115-120 grain bullets a bit faster.

If you are planning to shot the lighter 25 caliber bullets for predators inside 300 yards, the advantages of the AI cartridge are still there but they are diminished in difference from the regular cartridge. Both will have very similar trajectories inside 300+ yards.

If you do decide to go AI, be sure that your smith understands that the barrel needs to be set back at least one thread to properly chamber the AI cartridge. Sadly there are smiths working today who will simply run an AI reamer into the Roberts chamber to increase the shoulder angle to 40° and to straighten the case walls. What you end up with is an AI chamber with excessive head space and resulting case head separations with the cartridges
 
Another plus to the Ackley shoulder is that you don't have to trim your brass as much. I shoot a 280 AI with Nosler brass and I have reloaded this same 50 pieces 3 times with little effect on the brass. If you can find the PO ackley reloading book they are a real good read.
 
I had one in a Mauser action and it had feed issues with the AI shoulder, may have been the gun and not the round, but it was enuf of a problem that I got rid of it
 
Quote:The big advantage with the AI cartridge is that you can shoot the heavier ~115-120 grain bullets a bit faster.

If you are planning to shot the lighter 25 caliber bullets for predators inside 300 yards, the advantages of the AI cartridge are still there but they are diminished in difference from the regular cartridge. Both will have very similar trajectories inside 300+ yards.

If you do decide to go AI, be sure that your smith understands that the barrel needs to be set back at least one thread to properly chamber the AI cartridge. Sadly there are smiths working today who will simply run an AI reamer into the Roberts chamber to increase the shoulder angle to 40° and to straighten the case walls. What you end up with is an AI chamber with excessive head space and resulting case head separations with the cartridges

+1

I have a .257AI built on a Ruger M77 and love it!!
 
The bad thing about a .25 anything is the lack of acceptance by the American public and the lack of choices for reloading the other calibers enjoy.

I can see the 257ai as a better option with heavy bullets and a better BC over longer ranges.
 
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