James B,
I have to agree with Graybeard when he said;
If you come within 180 fps of the .257 Whby. velocity with a .25-06 in same barrel length you are either:
1. Grossly over loading the .25-06
2. Grossly under loading the .257 Whby.
3. Or you have a really fast .25-06 barrel AND a really slow .257 Whby. barrel.
The velocity difference with same weight bullets should be closer to 300-400 fps.
I love the
"Quarter Bore" cartridges, in fact I collect .25 caliber rifles. I have been reloading the .25-06 since long before Remington adopted(was originally called the .25-06 Niedner) it and gave it their name(40+ years). I currently have three .25-06's(Ruger M77V, Ruger No. 1b, Rem. M700 BDL Varmint) all with 26" barrels(factory). A
MAXIMUM load of 55.9 gr. of RE22 behind a 100 Nosler Partition gives an average of 3,351 fps.(at a pressure of 61,100 psi) from all 3 of my rifles. This charge shows excessive pressure(flattened or extruded primers) on all cases and in my opinion should
NEVER BE USED. A charge of 62.1 gr. of H4350 out of my .257 Weatherby Mark V Deluxe yields 3717 fps.(at the same pressure of 61,100 psi) using the same Nosler Partition. Again this load is to be considered
MAXIMUM and again in my opinion should
NEVER BE USED.
The reason I used these two loads is because of the same pressure levels(as per the folks at RCBS tests), out of the same length barrels, using the same bullet and both maximum loads showing the same excessive pressure signs. You should always get an average of 300(+/-) fps. or more from the .257 Weatherby over the .25-06 in rifles where everything is equal. Data from reloading manuals are to be used as guideline only. Every company that produces a reloading manual has their own set of guidelines as to what they consider to be minimum and maximum charges according to what their lawyers say(the old liability issue). Small groups and tight lines to you. Lawdog