Finally got out to the range to shoot some groups down range. Had several guns I was working with, one of which was my Japanese made Mark V in .257 Weatherby. It is bedded in a fibermark stock and has a 26" pipe.

The loads all consisted of the Barnes 100 grain TTSX, Weatherby brass and Federal 215M primers. Only the powder changed.

Here are some pics of the groups I fired with various powders, and chrono readings if I could get them.

The first pic is of a load consisting of 69 grains of IMR 4831. The one chrono reading I got was 3,493. Not real impressed with the group or the speed. It should be noted that one of those shots was a fouling shot as I forgot to take care of that.
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The next pic is of a load consisting of 73 grains of IMR 7828. Two chrono readings at 3,584 and 3,527. Speed is getting there, but not at all impressed with the group, or the stringing of the group.
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The next pic is of a load consisting of 77 grains of RL25. I got three readings off of this load. The velocities were spread quite a bit at 3,728 3,628 and 3,551. Not sure what the deal is there, but the group didn't turn out too bad considering. This powder charge was my load for the Barnes 100 grains TSX.
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The next pic is of a load consisting of 72 grains of RL22. I got three chrono readings off this load as well of 3,612 3,601 and 3,653. Very acceptable velocity and a nice triangular group.
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The final pic is of the final load I fired for the day. It consists of 80 grains of H1000. I only got two chrono readings that came in at 3,672 and 3,656. Very acceptable velocity, but ended up with the two in one, one out syndrome.
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So, I need to load up some more and see what one or more of those loads can do on a more consistent basis. If you were in the drivers seat and wanted to finish this up as quickly and efficiently as possible what would your next step be?

Thanks.

I'd pick your top three most accurate loads, and try them again, but with the ttsx seated deeper.

Then I'd load the most accurate of those and be done....if I was in a hurry.

If I wasn't in a hurry, I'd shoot several more 3 shot groups and look for what is the over all consistantly best grouping load.

These were loaded to an OAL of 3.140" How much further would you seat them - .005, .010??
Thanks.

.010" less, and try again with the h-1000, RL22, & RL25. Maybe even the 4831 if you wanted to try it.

Good luck.

At 72grs of RL-22 your a full grain over max for the 100gr TSX/TTSX in every manual I have seen. That being said, my favorite load for the 257 Weatherby (Which is also my favorite Cartridge) is 67Grs of RL-22, 100Gr Barnes TSX, Weatherby brass and CCI 250M primers. It runs 3460Fps and does a .788 C to C Group, out of a Vanguard Sport.

It shoots better than mine.Ive shot mjne so much it needs a new barrel. Mine never did shoot better than 1.5 or 2 on a good day. Your gonna have a hard time gettin close to the lands in that Weatherby.

The groups are so similar in size, and with only 3 shots of each load, that I don't think you have data that is really very useful. You might try testing one powder at a time using the ladder method. It has been discussed here before.

Please don't, for God's sake, go over max. As you can see from your tests, velocity can vary. Which means that pressure is changing, too. The folks who make loading manuals know how much variation occurs with different powders. The max load is calculated to protect you from the seriously overpressure round. It isn't the average pressure that will do you in, it's that one shot that is at the right end of the bell-shaped curve.

Hey 300, didn't I just see these pics on another forum ? Anyway, glad to see you seem to be going down the right path. My load really wouldn't make a difference here as I am shooting a Vanguard so it's a 24 inch barrel.

What I did do was chrono factory ammo with the 100 grain Barnes bullets averaging 3555 and was able to reproduce that with just shy of 71 grains of IMR7828 with the same 100 grain Barnes bullets. I seated them to the same length as the factory ammo measured at the ogive. I don't have my notes handy to tell you what that was though. Being a 24 inch barrel it is probably that the burn rate of 7828 is just right for that length of barrel. I use 7828 in my 338-378 with 225 grain Barnes TTSXs with very close to factory velocities. I go WAY slower loading the heavy 265 grain Barmes LRX bullets using US869.

One thing to remember about 7828 is it is a bit temperature sensitive. I saw up to 80 fps difference between 72 degrees and 108 degrees. I am betting that the load when it was hot outside was close to max pressure. This is for my 338-378 and the load is a bit on the light side anyway but it still got my attention.

Ken....

I am shooting a stainless Mark V with 26" barrel. The favorite load for the gun is 75gr of RL25 with a 100gr Sierra Pro Hunter bullet. The groups with that load will average under .75" with some groups as small as .2" and velocity right on 3600fps. The load I am working on now is 75gr of RL25 with a 100gr Barnes TSX with OAL of 3.22". They seem to stay under 1" at 100yds. It also seems to shoot well with RL22 but I have not chronographed those yet.