Bullet seating variations for fclass or BR, whats acceptable?

[DngBat7]

Your bullet seating process should be held to the same standard as your case sizing, base to datum (aka headspace), since that is what the chamber references from. Additionally, your sizing die should have the exact same angle in the shoulder as your chamber. If not, you're likely just chasing your tail.

So if you mistakenly bump back the shoulder an extra .002, and you're seating into the lands, your bullet is going to end up .002 deeper into the lands. And vice versa if you don't bump back far enough. And is seems to me that if the die is changing the angle of the shoulder, you'll get an inconsistent placement in the lands when the firing pin hits and drives the case tight against the shoulder, cold forming it to conform to the chamber.

But I'm no expert, so others may beg to differ. YMMV.

BTW: X-47B....incredible advancement in flying technology. Too bad it took the Gov't 40 years to figure that out. Or maybe they were just making sure to not leap way ahead in technology in order to keep the Cold War going longer. Imagine if we had a stealth bomber in 1949. Hmmmm...boggles the mind.

I actually think we did get the idea in 1944 from the flying wing we took from Germany.

 

[Texas10]

Yes, the Horton flying wing. In the Smithsonian I believe.

 

[chop house]

But if seating die is set and a inanimate object the only variant can be the bullet unless it a compressed load.
Correct?
Same goes for measurements. If all are consistent with given set of tools the outcome should be repeatable?

well, yes and no imo. the easy one first. micrometers have a slip clutch, calipers (at least mine) do not have the same feel. micrometers have inline force, whereas calipers jaws act as a lever and readings 'can' be manipulated by closing speed/force if not careful.

now, seaters. my wilson inline drift does not always play well with some bullets designs (not talking about vld's even). if i get too much neck tension, some bullets (typically light jacket varmint bullets) will leave an impression where the contact is made. the mechanical advantage of the drift on the sloped surface of the ogive will amplify the inconsistent seating depth.

i like boyd allen's mention to seat all long, sort, then tweak. of course comp br shooters are not going to be deforming their bullets in the first case...

and finally, 243win's post about controlling start pressure by always have the entire bullet contact area in the neck turned on a light bulb for me. i have struggled with short light bullets in long factory freebores not sealing. Aha!

hope this is helpful in some way.

 

[chop house]

sorry, the references above are in this related post:

http://forum.accurateshooter.com/threads/load-development-with-neck-tension-first.3977374/