257Roy question

KNOTFERSAIL

KNOTFERSAIL

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

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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.
 
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.
 
KNOTFERSAIL said:
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.
Click to expand...
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.
 

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