any plumbers on here

[Dan Hintz]

Yeah, I always remove gaskets when I can, but some valves don't allow for it. I'm trying to replace all gate valves will ball valves as I remodel... why can't someone make a copper ball valve...

[Curt Harms]

I did some copper sweating a few years ago and had a devil of a time, especially with larger fittings. My torch at the time was sort of a pencil tip. I recently got a new self starting torch with a larger hotter head. It made a huge difference in the quality of the sweated joints, especially larger fittings like valves. I will second shark bites, especially if you have a joint where you just cannot get it to stop drip--drip--dripping. There's a bonus function for the self starting torch. It works great for starting lump charcoal grills.

Dan
The torch is holding you back. Copper to brass can be done with Propane, but it takes additional time to prehest the brass body, and the copper fitting pipe introduced after the brass is heated to stop the copper from heating up too much and the solder not flowing properly .
With MAPP gas the job goes much quicker. You still have to remove the soft components from the brass valve body, and take out the stem/plug to reduce the mass that need to be heated. Clean the brass body really well also to remove all machining oils.

Once you use MAPP for asweating copper, you'll throw away the torch adapter for the propane tank.