I have custom .300 Wby and it does have freebore. The freebore's diameter is tight enough that I cannot measure to the lands because the bullet will stop against the beginning of the throat. I am wanting to load 180 TSX's but am not sure were to seat them. I know I cannot touch the lands, but how far should I seat back from the beginning of the throat? Any one have suggestions?

I have a 300 in a Mark V and the only restriction for me is the length of the magazine. I seat the bullet out as far as I can and still fit in the mag.. Shoots very well for me with that set up.
Doug

Your question is a good one...I have an original
.300 Southgate Weatherby build when Weatherby used a Belgian FN Action, before their own design. It has freebore. I usually load length as much as I can without touching or grounding on anything.
My O.A.L. with Nosler 180 gr. Ballistic Tip bullets is 3.626". I would think with the freebore, you can load as long an O.A.L. as possible & would be fine & probably the best. My opinion, not always
the best, but from my experience...
Best Regards, Tom

I have a couple weatherbies where the clip length lets me get to 3.690". I usually start with as long as I can in the clip/magazine box and see what happens. If not great backup in .020-.030" increments...you may find a "sweet spot" at deeper seeting depths. Being close to the lands doesn't necessarily guarantee accuracy in any rifle. It's kind of a crapshoot...experiment and your gun will speak to you.

The length when the bullet touches the beginning of the throat is shorter than the magazine box length. Another reason for this question would be because the TSX bullets need to be seated farther back because of thier structure. Since I cannot touch the rifling should I seat back from the beginning of throat?

I seriously doubt that your throat is that tight. More likely it is your runout. Crooked bullets will scrape the throat and give you false readings. Seat to magazine length.

If i do seat to magazine length, I have to force the bolt closed, and when I try to extract the loaded cartridge it will stick.