The seating depth for any particular bullet is very dependent upon the bullet shape.
Older bullet designs often have a Tangent shape for the tip and the newer designs have Secant shapes which are more pointed. The more pointed the tip, the more of the bullet tip can be seated into the barrel past the lands before the ogive touches the lands.
That would mean the OAL could be longer.
Measurements, like the one you made are pressing the bullet ogive into the lands and the measurement from cartridge base to tip (OAL) is what you are measuring after you take it out.
Cartridge base to ogive measurements are made using the tools that you referenced but don't have., but the OAL measurement is the same regardless.
By the way, I measure every group I shoot and take very detailed notes. I have records for multiple rifles in different calibers and just passed the 56,000 reloading mark.
i find that changing the seating depth (OAL) for any particular bullet is not as much of a factor for accuracy as you might think.
Finding the bullet weight and bullet shape your particular rifle likes is much more of a factor.
Also, some barrels also seem to have preferences for powders and temperature if you are shooting a temperature sensitive powder.
I have a model 12 .223 with a 26-inch barrel - probably the same barrel length as your BVSS.
My Savage has 4,000 rounds down the barrel so there is some throat erosion in the chamber (probably on the order of 0.040 or more.)
That requires me to seat the bullets out further to get the same jump as I had when the chamber was new.
I regularly load 77 grain SMK bullets out as far as 2.370.
I have loaded the Hornady Match 68 grain #2278 bullets out at 2.298.
The Hornady 73 and 75 grain ELD-Ms are very new designs and very pointy shapes. They may be able to load out 0.200 longer than the old designs.
The 60 grain V-Max is a lighter bullet that the 68 Hornady so the bullet length base to tip should be shorter. The bullet body touching the neck will determe how much you can seat it out before the neck tension starts to become too light to maintain consistency.
Don't be afraid to seat it out, but be aware that shorter, lighter bullets can actually be out of the neck before the ogive touch the lands. I have had that happen with 52. 53 and 55 grain bullets in just about all of my .223 chambers.
That said, the Hornady Match 68 gr bullet is an old design and shot groups in the 0.650 range in my rifle, compared to Sierra 69 gr SMKs that average 0.283 for 143 5-round groups.
If you want some cheap bullets that shoot pretty well, the RMR 69 grain bullets (that they claim to be SMK clones) averaged 0.305 for 23 groups and cost about 1/3 as much as the SMKs.
Bookmarks