Welcome to the forum
bigpappa
I shoot an Omega along with several other TC inlines and a couple hawkins.
I avoided the BDC because of the problem of barrel harmonics, the first qualification for long range is accuracy if the gun wont shoot that load accuratly then you can not hit with it. The cross hairs set normally with it so you can set them at 100 and shoot to find out where the other points of aim actually hit and still make use of them.
What ever powder you have been using is a good place to starteach has several advantages and disadvantages and you will find not all the people here have an open mind about that.
As for sabots the majority of Omegas including mine will shoot the MMP-HPH 24 best but there are exceptions, the 250 Shock Waves are packaged with them. Th best bullet to buy in bluk as far as I know at this time that is good upto 150 yds is the the 250 Gold Dot for deer size animals and the 300 for elk sized although for guns the prefer loads under 120 gr RS I like the 250 & 300 XTP, the Shock Waves are an excellant bullet for heavy loads and long range if you need an extreme range bullet the 50/40 200gr Shock Wave has nothing that compares with it I have used it on deer and boar both close and far with excellant results it has an excellant BC and SD. The 200 gr 40 cal. XTP will work with the same sabot.
http://www.mmpsabots.com/
http://www.harvesterbullets.com/
These are the sabot co. pages.
I recommend taking out the breach plug and trying some different petal thickness sabots befor you spend money time effort and frustration at the range.
If they are not a bit tighter than you would prefer they proably wont shoot good, if they are so loose that they go down easy they might move and act like a barrel obstruction, if they are so tight you have to pound on them they wont shoot good anyway.
For the first time out I suggest 250 Shock Waves and 90 grs powder, remember these are cut barrels and you need to put about 100 shoots through them before they will be broke in.
Also be sure to scrub your barrel good and get the factory preseveritive out if if burns in it will cause problems for months.
I hope this helps
Lee
PS let us know how you do.