My friend is trying to develop a load for his Weatherby in 257 Roy. We started out with H1000 and and 4831. The bullet is a 117 sgk and Winchester primers. The bullets were seated to 3.220. The h1000 gave great velocity 3420, 3450, 3480 fps for 73.0, 73.5, and 74.0 grains respectively. About 1 out of 4 rounds would have soot near the primer, be it a ring in the primer pocket or smudges on the backside of the base. Primers were not flat at all and extraction was easy. Cases were once fired factory rounds.

Also the groups were about 0.4 vertical but 1.7 horizontal.

The 4831 was about 250fps slower and the accuracy was a hot turd.

Thoughts?

try Federal primers there a hair bigger

Pete, I texted him last night that dang near every 257 load I saw was listing Fed 215s and that we should try them. Really, they're a hair bigger?

24 or 26 inch tube? 3,480 is rolling pretty good with a 117. That's generally where a lot of people top out with 110's in a 26" barrel.

It's a 26" barrel I believe. For comparison we ran factory 115 Nosler BTs that day at 3495ish.

i agree that is very fast maybe too fast ? is that a Weatherby mark 5 action ? OR a Vanguard / Howa action ? the reloading books are all under 70 grains with H1000 for 120 grain bullet. in my 257 Weatherby Mag. i use Reloader 22 -71 grains,100 gr,bullet Remington case, fed.215 primer i get 3700- 3800 fps out of a 26 inch tube and that has been pressure tested at a ammo factory at 56,000 sami psi.with my Ruger #1 and my rifle is over the reloading book specs too,but Ruger #1`s have a stronger action . he needs to use less powder before he blows that action up and/or get`s hurt ,especially if its a Howa action .i am 3 grains over max your friend is around is 7 - 8 grains over max thats dangerous. i checked powder max from the new Speer reloading book #15.

Hogdgen lists 70.0-74.0 for a 117 hornady spbt, I figure the sgk and the hornady spbt could be used interchangeably or nearly so. The rifle is a MK5 action Lazermark. The 73.5 group looked the best, still had some horizontal stringing. might play with seating depth. There are no intentions of going over 74.0

Hmm. May just be a fast barrel if you got those speeds with factory 115gr stuff. Good deal. And I'd probably come to the same conclusions regarding the listed load data and swapping Sierra for Hornady.

Check the lot number on the Win primers. Some lots were known to leak. Google it.

yes your right Hodgdon goes up to 74 gr. H1000 surprised me compared to Speer ? must be those Winchester primers,glad its a Mark 5 action. have fun reloading hope you guys figure it out ,maybe try Federal 215 ?

This. It's a problem with the unplated brass colored WLR primers. I've read of some problems with WLRM's, too. How does the boltface look?? Any erosion or pits?

I'm not sure about the boltface, the rifle is at his house. I'll ask him to take a look.

Really pete ?

.....all loads are UNDER 70 grs. ??

.....you checked the new Speer. hum, How about the REST of the reloading books ? ?


Guys..... pay attention. A word to the wise.


Jerry