Jam is NOT the be all and end all of seating depth.Years ago, I found a way to make almost any rifle shoot much better with very little work. Never got a chance to capitalize on it one bit- life happens- but I've kept it under my hat for over 20 years and I'll be damned if I'm giving that secret out until I've exhausted every means to get it patented and do something with it.
Top competitive shooters aren't giving away all of thier hardest learned secrets. That would be stupid.
They also aren't here talking about it. They're over on youtube making money on views by stirring up heated debates, controversy and confusion.
Eric Cortina isn't winning matches using ammo he loaded while doing a live youtube video like he wants you to believe. I've seen him distrectedly fumbling bullets while stuffing them in the necks, drop a loaded round, and put it in with the rest.
That said, We've got some pretty **** good shooters here that do freely talk about what works for them, and its easy to see the patterns when you get enough of a sample size.
Some bullets like jump, some don't and it has to do with the shape of the bullet ogive where it meets the bearing surface. But its not as simple as it sounds- Several things to consider at once- bullet ogive shape and jump distance influences pressure curve shape influences node characteristics influences accuracy.
The other is accuracy of bullet placement in the bore axis (both dimensional and center of mass of bullet to consider). Bullet shape and forcing cone shape have a definite influence on this- tangents go into the cone straight easier than secant, so they don't have to be jammed as close. Throw all these things into the mix in one violent explosion and its easy to see how people get confused about what's influencing what.
So like I said, look for patterns, and try to keep separate things separate so you're not chasing your tail
BR shooters use different chambers and different bullets in comparison to F-Class shooters. Chamber design influences seating depth just as much as bullet type.
Rarely have I mentioned on here exactly which bullets for competition I’m using, but I will tell you that I never jam because I never find it to make much difference to my aggregate scores. When I’m shooting strings of 50-80 bullets, I don’t care that a jam resulted in a few very tight groups while the load that was .010” off produced 1/4 MoA every time it was shot…which is gonna be used?!
Yes secant ogive is different to tangent, but the seating depth is still what is most important, tuning after this with powder and primers is rarely the deal breaker.
Anyway, I’ll let you believe that jam is king.