Here is what I hunt: Javalina 40lbs, Cous Deer max 75 lbs, jackrabbit, coyote, other small vermin and critters. I also have both an Encore and Contender, what wildcat caliber would you choose, for either gun and what length barrel and why. My max distance is maybe 200 yards on a good day.
Thanks in advance.
Based on the above criteria I believe that your best option would be the 6TCU for the Contender from a 14" or 15" barrel. If you select the Encore then I would take advantage of a little more case capacity and go with the 6 BR from a similar length barrel. This gives you plenty of choice in bullets as you will want a tougher bullet when going after Javelina or deer (something in the 80-90gr range) or lighter bullet when after small stuff (55-75gr range).
I don't think the 6BRM is a bad choice as you will surely get a little more velocity than from the 6 TCU...I just don't think it is enough to go with the bigger head size and make stretching your frame easier. The little 6 TCU will give you PLENTY of velocity to make things happen.
Truth be told, there are lots of cartridges in the 6mm to .30 cal range that will do a fine job for you. I'll list some of the ones if you want to research them...
TCU series (6, 6.5, & 7) - based on improved .223 case
BR series (6, 6.5 & 7) - based on BR case
BRM series (6, 6.5, 7, .300) - based on improved .30-30 case
* other similar entries... Bullberry series, Classic series, etc.
JDJ series (6, .257, 6.5 & 7) - based on improved .225 case
US series (6.5 & 7) - based on .219 Donaldson Wasp so I guess this is technically a .30-30 based cartridge.
Well I hope I've given you some information to look into, but not totally confused you. Like I said, I prefer the 6 TCU rounds or the 6 BR. The 6 BR give you the advantage of having factory brass available.