I have the latest edition lee manual with a couple of 80grn OAL guides in it but there not for the same bullets as I'm using,
i have an RCBS precision mic wich I think I've got the hang of.
I'd be very wary of using the COAL published by any manual but especially when putting "funny" bullets into a standard cartridge.
I've owned a couple of 22BR and a 22-250 shooting heavy'ish bullets and learnt from the first one to leave the throat "standard" and, as I put it to the 'smith, “Leave the throat for the right length for 69grain Sierra MKs and _no_ longer.” The reason for this instruction being that I hoped it might give me (now proven) a bit more barrel life.
My current 22-250 has a 1:7" barrel is set up as per this. For target use, I normally use Berger 80grain VLD but it seems to be happy enough with 40grain VMAX through everything else except Nosler 60grain Partition which was a bit like a shotgun.
The COAL varies a lot with the bullet design and I attach the photo as an example. NOTE: IT'S AN EXAMPLE AND NOT FOR YOUR USE!!!
The "red tipped" moly coated one is a 75grain AMAX, the other moly coated bullet is a 73grain Berger and the normal looking one (actually HBN coated) is a Berger 80grain VLD. All of them are seated to just engage softly into the rifling and that's where I develop my loads. I will acknowledge that this isn’t always “optimum” for some and that I normally use a 55grain Sierra HPBT which is set to a book length. However, that is not for ultimate accuracy and I don’t want any functioning issues when in the field such as a bullet stuck up the throat or a simple failure to feed.
As has been mentioned by someone else before, the Hornady gauge is a simple route to getting the length “right” for setting the bullet up to the lands (for target use, I assume) but it isn’t the only way.
I have the RCBS gauge (in 308, which I don’t own any more) and it worked fine.
However, I found that I refining a little bit and, maybe, “wasting” the odd bullet allowed confirmation of the amount of engagement I thought I wanted.
To date, I’ve found it simple enough not to use the gauges but, using an unprimed / unloaded case, just seat a bullet “long” and see if it engages into the lead. Hopefully, it will…although I owned a shot out 303 that wouldn’t!
Estimate the amount of additional back off needed and repeat. It’s pretty obvious when you’re in the right ball park for length and if you go too short then try again with a new case/bullet etc.
End note: Try full length resizing just a handful of cases first as it wouldn’t be the first time I’d heard of a rifle not taking to cases fired in another.