I recently inherited a custom made 257 Roberts Imp. that has several boxes of reloads from my Grandpa. All the boxes of shells have the following load written on them. He is using 48 grains of H4831 with a 120 grain Speer Spitzer BTSP. With the amount of boxes he had reloaded I would think he had found something he liked, but before I go out and try some , let me know if this is a fairly safe powder charge. If he was loading them pretty hot, I would like to know so I can be on the lookout for any pressure signs. I am having trouble finding a lot of info on reloading this cartridge. Also, in your opinion would this be a good load for blacktails. Eventually, once I have a good pile of brass I will begin doing my homework and reloading them myself, and I won't have to ask dumb questions. Thanks.

My best rifle is a 257 Roberts Ackley Improved

Quickload thinks that bullet, that cartridge with 2.775" OAL, and a 24" barrel will give 2965 fps and 49 kpsi, with a muzzle pressure of 11,225 psi [it is going to be loud].

Quickload thinks that my favorite load: 75 gr. Vmax with moly coat by Russ Haydon, 45 gr. IMR4895 bulk, 3.5" OAL as measured with Sinclair bullet comparitor is 3439 fps and 42588 psi. It measures 3620 fps.

When I overload, 49.4 gr. gives 3942 fps, the primer leaks and the the brass is too big in the primer pocket, as the extractor cut grows .0035". Quickload predicts this to be 56,272 psi and 3739 fps.

This is typical of Quickload predictions. When I overload a rimless case until brass flows, Quickload thinks that the pressure is between 55 kpsi and 65 kpsi.

That gives me some confidence in predicting that Grandpa's load is between 2 and 4.5 gr. less than the threshold of very short brass life.

--
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Yes, I would think that's a safe and relatively mild load. Nosler 5th Edition lists 50.5 gr H4831 as max for a 120 gr Partition. I'll bet your Grandpa knew what he was doing.

As a point of reference, I have a regular Roberts and have loaded 115gr NP w/ 49.7gr H4831 with no obvious signs of pressure. But every rifle is unique, of course.

John

In my .257AI, I use 52 grains of H4831SC with a 120 gr. Sierra Pro Hunter. It's a max load, but I can shoot the brass 10 times (or more) without primer pockets loosening. I get 2985 fps, according to my records. I'd say grandpa's load would be fine.

Joe

[ 10-19-2003, 18:15: Message edited by: jfk ]