Can anyone here tell me what action length Ruger's M77 chambered in 257 Roberts is built on? Is it the 30-06 length standard action or the 308 length short action?

I have a M77 Mk II action that I have thought about rebarreling to 257 Roberts (maybe 257 AI)and was wondering if this was possible and if it made sense. My action is a stainless steel short action.

Thanks for the help!

The factory .257 is on the standard action which is 3/4" longer than the short action. It should work on your shorty though but your bullet selection may be a bit limited by the max. OAL of the magazine. I do note that the 6mm which is basically the same case, is on the short action. My data shows the OAL of the .257 as 2.775" and the 7-08 at 2.800" max. and .308 at 2.750. Measure your magazine length to be sure how much room you have. It may be a snug fit but seems like a worth while project.

I was afraid of that. If the factory uses the standard 30-06 length action then that pretty much kills the point of a 257 Roberts as opposed to a 25-06.

I have loaded, cycled, and fired 308 Win. rounds through this short action loaded to an OAL of 2.800" on a few occasions. It seemed to work fine. Sounds like that would help with my bullet choices in a 257 built on this action. I would tend towards the Hornady 100 gr., 117 gr. BTSP, and 120 HP for bullet choices. Do you think these could be loaded to run at 2.800" in a 257 Roberts?

Thanks,
Mark in GA

i have 1 257 on a short action & 3 on long actions..the short action is a factory m700 mountain rifle and there is definately a mis match between the magazine length & chamber throat,, the only thing that can be loaded .003" off the lands is the hornady 117 round nose..the rifle shoots sierra 117 flat bases & winchester 120 poweer points.really well

Writer John Barnsness (sp) has stated in the past that there is very little difference in effectiveness between the short and long action .257. Most of the short action rifles he wrote about were the old 722 and 700 Rems. Your Ruger should have a slightly longer mag. than the Remingtons, if I remember right. As far as throat length, if you rebarrel the Ruger, you can have it throated to suit the magazine. You'll probably lose less velocity with the short action than you would see as variation between rifles. I have two .223 rifles with 24" barrels that show 170 fps difference with the same identical load. My Ruger 257 standard sporter really likes the 75 Sierra hp. and 115 partitions! Got the whole range of suitable game covered with that combination!

quote:

I would tend towards the Hornady 100 gr., 117 gr. BTSP, and 120 HP for bullet choices. Do you think these could be loaded to run at 2.800" in a 257 Roberts?

For sure the 100 grain. I use them in my .250 Savage but not the heavier ones. I think they will fit the Ruger action but you need to find out how long those bullets are to compute OAL. Better yet get some bullets and cases and make up some dummy rounds to see if they fit or how deep you need to seat the bullet to fit. If it is a good fit, and I bet it is, use the rounds to show the gunsmith for proper throating.

Mark,

Just a couple of suggestions/ideas for your short action. A .250 Savage would be sweet and not too far behind the .257 Roberts. Also, a .260 Remington would be a natural. Just some possibilities to consider.

-Bob F.