Ogive COAL for .300 WSM

[AZBearMan]

I am new to reloading so I appreciate any basic info. I used a Hornady OAL gauge with comparator to find the COAL (measured from the ogive) in a Kimber 8400 in .300 WSM. I am loading 180 gr. Accubonds. My OAL to the lands measured 2.312", and backing off 0.020" gives me 2.272" (I took 5 measurements). When I compare the Federal Vital Shock Factory load with the same bullet and weight (what I typically shoot), they measure only 2.181", a 0.131" difference from my OAL measurement. I realize that factory loads are shorter generally to fit all rifles, and that all rifles and loads are different, but I was surprised that the difference was this much with the same bullet.

Does this seem out of the ordinary?? I would have expected subpar accuracy with the factory loads with that much jump, but I routinely shoot .75" to 1" groups (at 100 yds) off bags with this gun and factory load. I haven't loaded any yet so I don;t know about magazine fit or velocity or how these shoot, but I wanted to get some advice before loading up a first batch. Any insights are appreciated.

 

[mikecr]

I always seem harsh, but I'll try & help you to adjust terms and understand some basics.
COAL is cartridge base to bullet tip. It's useless beyond magazine fitting and loaded ejection.
CBTO is cartridge base to ogive. This is the reference point I believe you're trying to relay.
I think you mean CBTO at 0-DTL/0-ITL(distance to lands, into lands) measures 2.312". 20thou under this is 2.292, 40thou under, or 40-DTL, would measure 2.272.

As far as factory, or anybody else's ammo measure, they don't matter.
Your ammo is what you make, which is likely desired best for your gun.
Just keep safety in the beginning of any path, and strive to understand what you're actually doing.