Should I seat the bullet always at 3.290". This is the standard OAL that Hornady gives. The SST's has a cannelure. I tried a dummy round seating at OAL 3.290" and the rim of the neck did not even reach the cannelure. This makes the cartridge look funky. I then seated at 3.25" which was right on the cannelure. Should I do testing and adjust to higher OAL?
You are ultimately limited by the length of your magazine well as to C.O.A.L. I have a Remington 700 that has a loooooong lead and the best I could do was get it about .080" off the lands. This helped dramatically in the accuracy department.
My A Bolt in 7mm RM is loaded to SAAMI specs and it shoots 1/2" to 3/4" with everything I put through it.
I used to use H4831 but went to the short cut 'cause it meters through my Lyman DPS dispenser better with that short stick. I haven't loaded any other powder than that one 'cause it shoots so well--why mess with success. I will recommend you sort your brass by headstamp and hoard all of your Federal stuff--much better than Winchester, and somewhat better than Remington brass. Of course if you are buying brass, go with what you like, but I do like the Nosler custom stuff and you can often get it off their website as seconds for half price.
Tmoniz is correct as well; each bullet will give you a different C.O.A.L. as the ogive is somewhat different--in my experience particularly so with the Hornady bullets compared to Sierra, Nosler etc. The Hornady is a good performing bullet if it shoots accurately in your rifle. I wouldn't hesitate to shoot anything in North America with their 162 grainer.