Weatherby factory loads for 115 Nosler Ballistic Tip - I deconstructed the load - found the seating depth - the powder charge is 71.6 - but I don't recognize the powder - varying size small roundish grains - not all the same size that look "sorta" smeared / shiny

Much smaller grains that do not look at all like H-1000 or anything else I've got.

Anyone else know what powder they are using ?

Possibly Norma ?????

I have pics I can send if you might be able to recognize.

I have used RL-22 with my .257 Wby for years and it has served me will. I use it for 115 grain and 120 grain Nosler Partitions. Good luck with your rifle. Good Dhooting.

I have had good performance with RL25. But what you describe seems a lot like either Ramshot Magnum or Accurate Magpro.

I think we are good to go - I've found photos of Accurate MagPro - two or three sizes of spherical gray discs - that are kinda shiny

I use IMR 7828 in my 257 weatherby.

Factory 257 ammo is most likely loaded with a non canister grade of MRP powder.good luck finding useable quantities of MRP

You are never going to duplicate the factory load and powder because the factory powder is usually their own formulation. Weatherby and Norma is likely MRP. RL22 is very close to that.

I checked my records and use the following loads with my .257 Wby. 70 grains RL-22 with 115 grain Nosler partition gets 3472 fps and is extremely accurate. 120 grain Nosler get the same load and gets 3422 fps. All loads use Fed 215 Match primers. My rifle is a Weatherby Accumark with a 6X24 Burris Signature scope. This is my experience for what it is worth. Good Shooting.

Mine also likes IMR 7828

I've got a Cooper and a Mark V that both like IMR 4350.

As others have pointed out, factory ammunition is almost ALWAYS loaded with a non-canister grade of powder.

Every lot of powder varies to some degree. The manufacturer tests the lot and those lots which vary from their parameters (burning rate, temperature, ignitability, etc.) for "canister grade" (sold at retail for handloaders) are sold to ammunition manufacturers.

The ammunition manufacturer will test the non-canister grade powder and adjust their load so that it yields closely similar performance to ammunition previously sold with the same specs.

Bottom line: It is a fool's errand to attempt to duplicate a factory load, particularly to attempt to duplicate the powder used in it since that particular lot of powder will almost certainly differ from that which you can purchase over the counter.

By the way, even "canister-grade" powder will vary slightly in burning qualities, which is why it is a good idea to either (1) buy that you will need in the foreseeable future from a single lot or (2) if powder from a single lot is not available then mix the lots to create a homogeneous powder which will perform in the same way in every round loaded.

The original Norma 205, which was the precursor to Norma MRP/RL22, was especially subject to variations in its burning speed. One lot I had behaved beautifully in a particular "overbore" round, but the next lot cratered primers with the same amount of powder. When Norma replaced 205 with MRP (essentially the same powder) they did so largely to escape the reputation it acquired as "temperamental". They started paying more attention to lot-to-lot variations, but anecdotally it seems that MRP/RL22 still exhibits more lot variation than most powders. Yes, it's a very good powder, but pay attention to the lot number and if you change lots be sure to start with some sample loads to check the velocity against earlier lots.

What's that? You don't have a chronograph you say? Then you shouldn't be f-ing around with handloading rounds like the .257 WBY. Go get a .30-30 or a .308.

I use IMR7828 in all my 257 wby. 100gr.part bullets. Will shoot one hole if you can hold it. IMR 4350 for 117gr part with same accuracy . Good luck