Not sure who the name is owned by now. I think it might be Blue Ridge Knives. Blue Ridge is certainly a huge distributor of them. Blackjacks come in two flavours the stainless and rubber ones are made in china, and Bark River makes the rest.
I don't feel qualified to give much comment on them, but to get the ball rolling:
I owned some Blackjacks years ago. The Rio Grande was an awesome knife, the style just wasn't for me. I did tote an Anaconda for a while. I really liked that. Too much knife for me now, but I can't fault it nice Tarzan beater.
Although the Blackjack quality has bounced about a bit over the years, depending on who was making them and blah, I think think there is much more variation now. Bark River tends to polarise people. Some see their grinding to a thin cutting efficiency as a great thing. Others find such edge thinning an incongruous step too far on designs that a clearly otherwise built for rough work. There's plenty of threads crying about that. Personally I don't give a hoot about it. People that moan about that sort of thing shouldn't own knives. It's like having a car when you are only capable of making left turns, or having to get someone to put fuel in for you. Get off the road. Anyway, point being, whatever you stance on Bark River is it should generalize well to the non-stainless Blackjack stuff.
Of the stainless I have mixed views. I have bought two of the newer ones. One is great the other not so good at all. I've kept the Grunt. The move to China may well of actually improved that with a steel now more in line with AUS 10. That's a well done knife and very sharp NIB. I have thinned mine out some. That's not because there was anything wrong with it, that's just how I roll. I like rubber handled stainless knives with vicious cutting power.
If I were in your position and liked the look of the Tac-Ops 6 I'd grab it. In common with a lot of other knives of that type the scales look a bit flat sided for my personal taste. I wouldn't hold that against it. I've been spoiled by some loved contoured rubber handles. They are easy to make. Machining off micarta, G10, wood, to get the contours I like is always going to be much harder for makers to do. That aside, looks great to me.
