Another .257 Wby Question: Seating Depth

[Mike D Texas]

I will tell you this, nearly all Weatherby's like jump, 2 reasons, it lowers pressure and allows you to use heavier doses of powder and, it provides a smooth pressure curve. This I have tested using the Pressure Trace on several Weatherby cartridges.
You CAN seat close to the rifling, but with .024" of bullet in the neck, is it wise…

Cheers.

Yep, this. I don't even typically worry about jump in my 257WBY. It shoots tiny holes at SAAMI length with 115 Bergers and I can push them to 3650fps before I start to even see ejector marks.

 

[FEENIX]

Sorry. I was mixing some metaphors. I was not measuring CBTO. I was just explaining my situation using two different approaches. On the first, loading to mag length gave me a COAL where the bullet was barely seated in the case. On the second, I seated the bullet .257 into the case (one width of the bullet), which is something I've used as a rule for minimum seating depth.

RW

You might benefit from this article, https://bergerbullets.com/shoot-better/shooting-knowledge/measuring-coal-and-cbto/

 

[FEENIX]

I will tell you this, nearly all Weatherby's like jump, 2 reasons, it lowers pressure and allows you to use heavier doses of powder and, it provides a smooth pressure curve. This I have tested using the Pressure Trace on several Weatherby cartridges.

I am fully aware of WBY's design (long throat/freebore - .378" for .257 WBY), but it does not mean one cannot get closer to the lands, especially with today's longer/heavier bullets. They were also designed primarily for lighter bullets (100g range). I do know most stay in the recommended COAL, and others claim not to be able to get close to the lands. I am pressure testing my loads with 145 Black Hole and 163 Chinchaga at .015-.020" off the lands. So far, there have been no issues.

(110 TGK vs. 163 Chinchaga)

You CAN seat close to the rifling, but with .024" of bullet in the neck, is it wise…g

Agreed!

 

[fmuguira]

I found my best accuracy with 115 BT, 110 AB and 110 TGk at 3.410-3.420"

I spent quite a bit of time trying around SAAMI spec; 3.20" ish if I remember right and mine shot better (sub moa) at the stated 3.410". R26 running 3500 fps with 110 s and 3425 with 115. 1-10 twist and it's definitely a top end load.

Measuring oal with a Hornady tool to lands had bullet teetering in end of neck; definitely a no go!! Like about 3.575-3.6" length !!

Good Luck

 

[ColonelGoose]

Loading both the Berger 115 VLD and Hornady 110 ELDX. Touch lands with the 110 at 3.385 and 115 at 3.387. COAL for both is 3.300

 

[MagnumManiac]

I am fully aware of WBY's design (long throat/freebore - .378" for .257 WBY

That's all good for your heavies and the twist to shoot them, but it's not ideal for regular length bullets for a 10" twist.
This 257 Weatherby & my 270 Weatherby are the only Weatherby's I have with the 'factory' throat, all of my others have the proprietary length Roy used in the beginning which were altered several times.
My 6.5-300 Weatherby has .378"(my chosen length), my 300, 340 & 375 all have .500" as Roy designed. It works exceptionally well allowing heavier powder charges without excessive pressure.
Can't get to the rifling on those without seriously long brass solids…
I fully understand your reasonings for doing so, but it's not the norm.

Cheers.

 

[FEENIX]

That's all good for your heavies and the twist to shoot them, but it's not ideal for regular length bullets for a 10" twist.

I agree 131s and up are not ideal for 1:10"because it will not stabilize. My original comment was the ability to touch the land on SAAMI chambering. There are people redefining what is ideal and loading them close to the lands as well as folks pushing the 115 Berger in 1:7"