270 wby seating

[MagnumManiac]

Seating depth made a big difference in my 257. I m at 3.415" oal which runs fine in my Rem 700 action. It too has same .378 freebore as the 270 WB does.

I completely agree with this, I have (2) 257Bee's, 270Bee, 6.5-300Bee, 300Bee, 340Bee & 375Bee. The latter 3 have .500" freebore (parallel sided .0005" over bullet OD) and they still tune to seating depth within the magazine length. The other 4 also tune to seating depth.
Being close to the rifling means very little, tune occurs with barrel time, this can happen at .100"-.200" from the lands…and anywhere in between.
My custom 9" twist 257Bee is very new, although I got a 3/8 MoA group with the first Retumbo load I tried with 110g Accubonds, next are the Berger 115g Berger. Haven't decided on a heavy yet, 130g something comes to mind. Couldn't get a 8" twist blank.

Edited to add:
Try H1000, it is accurate with lighter bullets too.

Cheers.

 

[FEENIX]

Being close to the rifling means very little, tune occurs with barrel time, this can happen at .100"-.200" from the lands…and anywhere in between.
My custom 9" twist 257Bee is very new, although I got a 3/8 MoA group with the first Retumbo load I tried with 110g Accubonds, next are the Berger 115g Berger. Haven't decided on a heavy yet, 130g something comes to mind. Couldn't get a 8" twist blank.

As with anything else, YMMV. I was not looking for any group/accuracy but rather doing a pressure test with powders I already have open. Below is with 67.5 of MAGPRO and 145 Black Hole bullets at 200 yards .015" off the lands.

My .257 WBY barrel is 1:7" and 22." I stopped loading the 145s because I was more interested in 163s. I am pushing the 163s with H1000 at 2915 FPS. I have some loaded with Retumbo but have not yet made it to the range. I will work on group and seating depth as soon as I decide what powder to use. Cheers!

 

[19 Badger]

140 Accubonds and 7828sc are a combo in my MkV that has been deadly for over a decade for me. Seat them long as you can.

My go to load in my .270wby for about 12 years as well...