I like using the 120gr.x in my 708 Whats the best powder and what kind of velocity can I expect in a 22 inch 700?

I use H4895 with the 120 Hornady. 41.5-41.8grs. is about max, and that should get you close to 2920fps. 44.5grs. RE15 will get you over 3000, but may not be as accurate, at least thats what I found out when working with the 120 Hornady. Jay

I use 50 grains of W760 with 120 B-tip for a velocity of 3100 fps.

Just called Mike @Nosler, they got the best accuracy with IMR4350, 49grs. being the max, but that load is compressed, then since my concern of a compressed load, he told me that another good one was Varget, 41grs. @2895, max 45 @3139.
Wouldn't mind using IMR4350, but it doesn't go through a powder measure very well, so I like to stick with small grain "stick" powders.
Now, just looked up and saw we're talking about the 120TSX, which I would probably never use in my 708, but if you like it, thats fine. Anyway, this bullet is probably slightly longer due to it's construction might need a smaller amount of Varget. OK, update, talked to Barnes reloading tech, his first choice would be Varget, starting load 39.5, max 43grs., for a velocity of 3050 from a 24" tube. he also mentioned the triple shock bullet that has the three rings that reduce bearing surface and may get better velocity and accuracy from. Just from experience, stay away from 760/414. Jay

I've been working up some 120 gr loads with Nosler Ballistic Tips and TSX. 22" barrel 700 Ti.

I started both with loads of Varget & RL15. Varget gave a little tigher inital groups so that is what I've been working with.

Nosler book max shows Varget at 45.5 grains. That has been my most accurate load with the BT's. Worked up very carefully (all shot over a chrony) and groups opened up at 45.8 & 46.0 with inconsistant velosity. 45.5 grains of Varget is now my max with the BT's. Last 3 shot group was in two holes @ 3060 fps.

With the TSX, I found a little less velosity with the same charge as the BT's. Worked this up also to 46.0 and velosity/accuracy was close to the BT's. This load needs more testing to validate.

H414 (W760) will probably give a little more velosity, but the temperature sensitivity will increase also (bad in Florida). I don't think IMR4350 or H4350 (my choice for 140 grain bullets) will get the 120's up to speed (my guess, not proven).

I'm shooting these all out of .308 Lapua cases necked down and turned. Powder capacity is reduced (46.0 max non-compressed) compared to Winchester (49.0 non-compressed) so may the 4350's will work with Win/RP cases.

Hope this helps and good luck.