i've got a custom built 257 weatherby mag and it shoots factory shells unbeliveably great! i'm wanting to load my own shells due to the cost of weatherby shells and the amount of shooting i do. would like to use the same powder that they use. what is it?

Attempting to duplicate factory loads is a fool's errand.

Factories use non-cannister grade powders and adjust the charges to compensate for variations in the burning rates from lot to lot.

That said, Norma loads the Weatherby ammunition and it can be presumed that they use one or another version of their proprietary powders, most likely a version of MRP. RL-22 and RL-25 are cannister versions of this powder. You might very well work up an excellent load with one of these powders (or one or another version of Norma MRP.) However, it won't be a "duplicate" of the factory load except to the extent that you might be able to achieve approximately the same velocity.

Yep What Stonecreek said.

I would look to MRP or maybe RL22. I've found lotts that load basically the same.

I am loading 75gr of RL25 with 100gr Sierra Pro Hunter bullets (Fed215M primers)and I am getting 3600fps with groups that average .5" or less. It looks like the same load with 100gr Barnes TSX's will group almost as well but I have not chronographed those. It also seems to like RL22 with the TSX's but I have not tested those very much yet. I think the factory loads with a 100gr bullet were about 3600fps.

quote:

Originally posted by kacole:
i've got a custom built 257 weatherby mag and it shoots factory shells unbeliveably great! i'm wanting to load my own shells due to the cost of weatherby shells and the amount of shooting i do. would like to use the same powder that they use. what is it?

I used IMR-7828 in a custom 257 Wby. Here is a good article with loading data.

http://www.shootingtimes.com/2...therbymagnum_031706/

RL-25 works well for me.

quote:

http://www.shootingtimes.com/2...therbymagnum_031706/

thats a great article to read thanks for posting it. makes me feel real good about my decision about building a 257. extreamly accurate with the factory shells and i know we'll get it to shoot with the reloads. were off to try some rl-22 and rl-25 thanks for the help.

RL22 normally works well in the .257 Wby. Try Barnes 100 grs (T)TSX, if they shoot in your rifle look no further.

- mike

mho--What load with RL22 are you using with the Barnes TTSX's? I'm currently using 75gr of RL25 with 100gr Sierra Pro Hunters. I just bought 4 boxes of the 100gr TTSX's to try in the 25-06 and 257Wby.

quote:

Originally posted by Ed Scarboro:
mho--What load with RL22 are you using with the Barnes TTSX's?

I'm actually breaking my own rules with this load. The load I shoot is on the hot side, and normally I don't stick with hot loads. But in this particular case, the load just shot really well in my rifle.... One problem might be the Norma brass, which sometimes tends to be on the soft side?

The Nosler manual specifies a max of 71 grs, the Barnes manual a max of 72 grs, some people posting here specify they have used up to 73 grs. My (hot) load is 72 grs.

Do be careful and work up from below.

- mike

67grs of RL22 weatherby brass, cci 250m primers. And 100gr tsx-ttsx for under half inch at 100 yards. 71 is max charge while 66 is minimal.

Thanks mho. I have shot up to 70.5gr of RL22 without major pressure signs. I think the best groups were around 69 or 69.5gr. These were with the TSX bullet. I just bought 4 boxes of the TTSX on sale for $26 a box. The best groups I have so far are with 75gr of RL25. I load several different calibers with RL22 so I was trying to work up a load that shot as well as the RL25.

I thought I would measure the difference in the length of the TSX vs TTSX and assume my OAL would be that much longer. It looks like the ogive will match if I do that.

quote:

Originally posted by Ed Scarboro:
I thought I would measure the difference in the length of the TSX vs TTSX and assume my OAL would be that much longer. It looks like the ogive will match if I do that.

That's a plan. I have to admit I rarely worry too much about exact OACL on Weatherby cartridges. The freebore is normally so long anyway, that one stands little chance of getting close to the lands. Since I doubt (although I have to admit I have not *tested* this) that a difference in distance to lands of .50" vs. .55", say, will make much difference, for Weatherby cartridges I normally seat the bullet based on where it fits well with respect to neck and shoulder of the case.

In the case of (T)TSX bullets, I normally also try to seat such, that one of the "driving bands" (?) closes the case mouth. Does this matter? I don't know, but it seems comforting that my ammo can't pick up "gunk" between the bullet and the case mouth.

FWIW - mike

So much for the plan. When I measured the bullet lengths and calculated the OAL, it didn't give much if any room in the magazine. I decided to just seat to the same length that worked for the TSX's and adjust from there after the test loads.

I tried the 100gr Tipped TSX's today at the range and they shot great with RL22. I seated to the same OAL as the 100gr TSX's and loaded 71gr of RL22. The groups were sub .3". I tried the old load that I have used with the TSX's of 75gr of RL25 but the groups were barely under 1".

just as a update i finally got some shells loaded and shot, 71 grains of reloader 22 with 100 grain tipped triple shock the groups were about 3/16 inch. thanks for the help

Be safe and check for signs for pressure. 71 is max in all my books.