257Roy question

[KNOTFERSAIL]

Me and my daughter both shoot a 257Roy, Hers a Weatherby mine a Rem cdl sf. We also shoot the same powder (different charge) and same 120gr partition. (Different seat depth)

Question is: curious more than anything, but does anyone have a factory loaded partition they could measure the BTO? I don't think the partition has been factory loaded for while now.

Thanks

 

[BLovell]

Unfortunately the only factory ammo I have for mine is the Hornady 117gr SST

 

[BLovell]

Oops, I read that as .257 Rob not Roy. lol. My bad.

 

[Aoudad shooter1975]

I'll see what I have..I might...

 

[Raudy707]

I have some old 257 Roy ammo. I'll go look...

 

[Raudy707]

Well this is an extremely old box of factory ammo but here's the measurement. I think that's longer than SAAMI spec?

 

[std7mag]

SAAMI spec is 3.209" COAL.
Drawing in the Nosler #8 manual has COAL at 3.250".
COAL tested for the 120gr Partition is 3.240".

So it's all over the place.

Seating out to be a certain distance from the lands will result in a much longer COAL.

Problem is that Weatherby utilizes a long freebore. This is an old trick to help keep pressures down.

The other issue is that the ejection port on the Mark V is short.
If you load out to the lands, you can't eject a loaded round.
Unless you pull the bolt out.
Which requires pulling the trigger.
I'll pass on that option, thank you.

 

[Aoudad shooter1975]

I've got a old tiger box with 3.312 COAL

 

[KNOTFERSAIL]

Thanks gents for your replies. Are these measurements factory loaded PARTITIONS you speak of? Also, if possible I'm interested in the Base To Ogive measurement, not the COAL.

 

[Raudy707]

Yes, 120 Nosler I'll go check the ogive in a bit.

 

[FEENIX]

Thanks gents for your replies. Are these measurements factory loaded PARTITIONS you speak of? Also, if possible I'm interested in the Base To Ogive measurement, not the COAL.

If you will hand load the 120 Partition, why worry about the factory CBTO instead of finding what CBTO your rifle "actually" likes? As with anything else, YMMV.

 

[Aoudad shooter1975]

I'm not home I can measure when I get back...if it's a westherby rifle you cannot seat it out far enough to touch the rifling

 

[Raudy707]

Comparator is exactly 1 inch so subtract 1.0"

 

[KNOTFERSAIL]

Comparator is exactly 1 inch so subtract 1.0"

Thank you for taking time to measure. I'm loading .080 shorter than your measurement.