I have Imr 4320, 3031 and 748. I suspect that I can shade book maximums some due to the strength of the G2 Contender action. Just wanting to know the best place to start.
Not sure what you are refering to by "shade book maximums", but start low and work up towards published max loads.
The T/C Contender is a good action but not as strong as a bolt action like a M70 or M700.
You should look at the 30-30 data for the T/C Contender handgun.
Nosler RG#5 and 6 list data for the 165 gr bullets. This would be a good reference for you since all three powders you mentioned are listed.
Initial shooting of the barrel began as emptying some brass from Federal blue box factory loads and shooting up some ammo I loaded for a marlin 30-30. The factory loads were 150 grain flat noses and shot pretty good,1 1/4 inches for 3 shots. The old reloads were put together for a rifle with a very tight chamber and were a bit sloppy in the contender chamber, had a couple misfires but these shot into 2 inches anyway, 130 gr. Speer flat noses on top of 34.5 grs. of IMR 4895. Rifle is surprisingly lively for a mild cartridge like the 30-30. The scope I put on it is a Weaver wideview of 70's vintage. It's short eye relief and squarish shape worked against me putting a divit in my nose. I continued after moving the scope forward and stopping the bleeding but it was just barely safe. I can see a new scope coming my way.
I am lucky to have a 25 yard range in my back yard and I used it to work up a load using 748, Winchester large rifle magnum primers and the 165 gr. B-Tip. I started at 32.0 grs. and got very mild pressures, the primer sticking up a bit as the case didn't push back against the action face, same with 33.0, and 34.0 but at 35.0 grs. I got a nice flush primer with no flattening and at 36.0 grs. I got a slightly flattened primer. At this point the 165 grain bullet is pressing against the powder charge so I settled on 35.0 grs. of powder. I will load 40 of these for my next range session after my new scope arrives.