Home Forums Reloading Big Game Rifles Questions with .257 Rbts?

Mark,

I do not have a chronograph so I can't tell you.
My guess would be 3000 fps, maybe a little more.

Regards,

JD338

Sierra 100 sfb, Load of IMR4064 shot that combo in 200yd bench matches, one hole groups. If you want to use the slower stuff rechamber to the 257AI, 3000 fps will be an easier more accurate thing.

Another trick I used I forgot to mention in my previous post is to vary your seating depth. I found that if I load mine about .002 off the rifling it shoots best. Noticeably better than using OAL listed in reloading manuals. But some magazines are short so you need to make sure cartridge will fit in magazine. Good luck as you can see from all the posts its one great cartridge.

I have not tried to alter the seating depth, I go with the listed C.O.L.. I have gotten good accuracy with a couple of the factory loads, but have not measured any of them. After I get a load that seems like a winner, I might try the different seating depths.

Well, I just loaded up some test rounds using IMR 4350 (don't have any H4350). I used from 43 grain to 45 grains in 0.5 grain increments. Hopefully I will find a load that my rifle likes. I didn't change the primers yet, I still had a bunch of the WLR primers that I wanted to use up.

I just did some load development (still finishing, not done) for my 257 Roberts M77 Ruger. I worked with R-P cases, Fed 210 primers, Hornady 100 grain Interlocks, and H4350.
My rifle seems to like 45.5 grains of H4350 with this combo. I am running the C.O.L. at 2.90" and getting good results. I pushed the rifle to 47.0 grains of H4350 and got 3159 fps with a 1.2" group at 100 yards. I'm not one to push equipment hard so I think somewhere around 45.5 grains @ 3020 fps is the ticket.
My 3 shot group was just under 1 inch and ES and SD were nice and low (of course, they mean very little with just 3 shots, but the potential seems to be there) so I'm going to load and shoot a bunch of groups and see where it leads.
This rifle absolutely hated 117 grain SSTs but really likes the 75 HP Hornadys and 100 grain Interlocks.
Good luck.