338-370 WBY reduced to 257 WBY Mag

[ISS]

Slightly off tangent, but is this a good time to mention my 22-378, aka the 22 Eargesplitten Loudenboomer? 60gr Nosler Zipedo solid base hit 5600fps and all of them got to the 100 yard target intact. Most others made beautiful little vapor trails about 30-40yds down range. It was written up in Precision Shooting Magazine between Gene Solyntjes and myself one weekend.
Most fun I had since going back to Ill to visit family and shooting Ken Green's Four Bore Double (yeah both barrels. I could not believe the recoil the first shot!). It was one of Ken Owens ten of them built 4-bores. Some things you just have to experience for yourself...

 

[cuznguido]

No your not, i say when you're dun. 8700 is discontinued but us869 is as close to identical as you could get. It is better than 8700. And it's better than lrt for pushing long heavy bullet's in overbore magnums. And if you look at the load data it shows 8700 makes the highest speed with heavy bullet's in the 257 weatherby/ thus us869 will also! So if a person wants both high velocity and excellent accuracy a person would use us869. The only reason i use us869 with 88 bibs is because of the incredible accuracy. So let me recap, with light bullet's us869 does not make highest speed but with heavy bullet's it does make the highest speed.

Your Weatherby must be yards better than any of mine. Been shooting 30-378 since back when 870 was king of the hill. I use US869 sometimes and IMO it aint even in the same league. H1000 does well as do some others. us 869 is acceptable, barely.