Sorry about jumping in so late to this fine thread. My 257AI is a HART 25" with a 1 in 10 twist. 75 gr Hornady's do 3750 ft/sec, 85 Nosler BT's do 3525 ft/sec, 100 Partitions do 3350 ft/sec, and 115 BT or Trophy Bonded do 3100 ft/sec, and 117 Sierra's, 120 Partitions, A-Frame, et al do just over 3000. These are all being pushed t the MAXIMUM over various powders. Accuracy is usually found at less than these velocities in this rifle. The 120 Partitions went through several Impala length wise much to my surprise, overall I rate this cartridge as the most you can have in a short action. IMHO anyway!!!!!

Have a M70 that was recently rebarreled to .257 Roberts AI the 40 degree version. Twenty four inch Hart barrel.

I used the data in the #5 NOSLER loading manual and loaded some 115 BT's with RL19. Chrono'd the loads and they are -200 fps lower than the Nosler manual.

With 50.0 grs of RL 19 and a FC210 primer I'm getting 2930 fps average. Really no pressure signs. Cases extract easily,primer hardly flat.

Sound about right?? I'm not trying to turn this thing into a .257 Wby but what can a guy expect to achieve with 115's or 120 NP's ??

Barsness wrote an article in Rifle ref the .257 AI and ALL his loads are 4-6 grains over the max listed in the Nosler manual. I know barrels are different,manuals are conservative, your mileage may vary,etc,etc. But what can a guy safely expect.

FN in MT

Frank, I have never loaded the heavier bullets in mine. I almost exclusively use the Sierra 100 gr. spitzer. Out of my barrel (24 in. McGowen) with 53.3 grs. of H-4831 and a CCI large rifle primer I average 3400 as clocked over an Oehler 35P. FWIW Jim

My manual #4 stops at 47.5 saying that is +P or 58,000. Loadtech takes it up to 51.7 for 3115 and 61,000. It gives 3075 for 50 grs. Make sure you seat the bullet out as far as you can and be off the lands and still function. That will give you maximum net capacity.

Frank, my 22" Douglas showed 3062 fps with 50.5g RL22 and the 120g Speer. 50g MRP did 3005 with the same bullet, and for a slower load 45.5g IMR4350 did 2900. These were from a short action Remington 700 with the bullets seated to 2.80". These were the only loads chrono'd with heavier bullets.

Frank,
I always felt that 400fps or more was too big a sacrifice for 15 gr. of bullet weight. I use 100gr. Sierra FB Spitzers for Deer and Elk, never had one fail yet.
Stepchild

Roberts load data is SO conservative in Speer, Nosler and my Sierra manuals. I wonder if the Ackley Improved data that Nosler printed is also conservative??
I loaded three rds yesterday with 51.0 grs RL19 same 115 BT,etc.... and they chrono'd out at 2975 fps. Shot into .7" at 100 yds. Holy crap but a 115 at 3000 is ALL I need for deer or antelope!! Can't bring myself to take it elk hunting. Too many elk rifles in the safe that barely get used as it is.
I still need to fireform some cases so I may try some 100 grain slugs as I have a variety on the shelf. This is the first .25" I have had in 20+ years. Had a pair of .25-06's then a short stint with a .257 Wby way back when. Like going back into my past and rediscovering something all over again.

FN in MT

Frank: I've never had a Roberts improved, but my old standby load for my 23.5 inch standard Roberts yielded 2930 FPS with a Sierra 117 grain boattail. The AI version isn't magic, but should yield another 50-100 fps at the same pressures.

Frank,
Forget the formulas. I have two .257 Ackley Very Much Improveds. There are many variables involved, barrel length, powder burning rate, etc.
I am using cases(W-W), from the late 70's so i'm not leaning on them too hard. 57 gr. Norma MRP gives me an honest 3,607 at the muzzle with a 100gr. Speer spitzer. This was clocked over an Oehler 33 and is listed in the Speer #8 manual going 3,410 with a 22" barrel. Mine is 27.5" and polygon rifled.
Some will discount the above as BS, but it's not! When I hear people talk about .257 Ackley's only gaining 50-100fps over the Roberts, I have to grin, I know better! And while i'm at it, I love the .257 Roberts.
Just as an aside, I was hunting in Wyoming with Jim White, a member here. He was using a Roberts and I was using my rechambered 722, .257 Ackley. He took the first shot and kicked up dirt in front of a decent Mule Deer and after the dust settled, I killed it. After the hunt he had his rechambered. It works well for me.
Stepchild

I must admit to being very interested in a 257 Roberts RCBS imp ie improved with a 28degree shoulder. Then again it would be very interesting to do that to a 6.5x57.

I don't like 40degree shoulders.

1894, If you're going to go with a 28 degree shoulder why bother to go improved at all? Just stick with a 25/06 and you don't have to wear your barrel fire-forming. Jim

Shot a very nice whitetail buck this past Sunday with the .257 AI. Used the 115 gr BT's over 50 grs of RL19. Hit him behind the shoulder at 180 yds, wrecking both lungs. Surprisingly he still ran about 50 yds.

FN in MT

Sept 9 2003
A) 257 Roberts Ackley Improved VZ24, Lother Walthar barrel

75 gr. Vmax .257 bullets that I had moly coated by Russ Hayden.

1) 49.4 gr. of IMR4895 at 3.4" with Sinclair bullet comparitor gives 3942 fps and the extractor cut grows .0035"

2) 48.3 gr. gives 3757 fps and the extractor groove grows .0005"

3) 47.2 gr. gives 3736 fps and no extractor groove growth

I get 2940 with IMR 4350 and Sierra 117gr BTs from my 23" .250 AI. I get just under 2900 with 117gr Hornadies and H4350 from the same rifle.

John

Well done Frank. What do you need that 6.5x.284 for?

Fred,

NEED? Probably like I need a 2nd bellybutton. I may just do a light deer/antelope rifle in the .257 AI and be done with it. OR do nothing and spend the money on another Freedom Arms revolver. So many interests and so little funding.

How did your trip turn out? Find anything??

FN in MT

Hey Frank, I was a bit tounge in cheek about yor 6.5 project , we never "need" a new rifle, excetp I do think you need a .404.
Found a nice 8ac lot near Helena, but someone else beat me to it while I was checking on wells/septic. Still looking though.