Don't see much sense in oven heat treating at 370 degrees. I'd have to believe you'd get the same results quenching from the mold. I use a toaster oven set at 450 degrees and get 33 BNH or so after an hour soak time and 12 hours set time. I also put the water bucket right in front of the oven door so it's a second or so from the oven into the bath, I think this is important. If you're going to HT a lot look around and find a good oven thermometer so you know what's REALLY going on and start looking at garage sales or Walmart for a cheap toaster oven. Best thing about the toaster oven is that you can use it in the garage and once you have your temp set you just unplug it and it's ready to go next time. Personally I don't like it when bullets stick together and throw those back in the pot. Had it happen and just turned the heat down a bit until it didn't. I doubt if the gun would know if the bullets were 33 or 32 BNH.
I'm also not big on dumping the bullets into the water, too big of a chance of damaging them that way IMHO. I found an old aluminum basket from a coffee pot and made a wire handle for it. I stand the bullets up in the basket, tightly packed, and dunk the whole thing into the water after they come out of the oven. I can only get about eighty 30 caliber bullets in the basket I have but it doesn't bother me and that's about my sitting in front of a hot pot of lead limit anyway.
Another thing I don't put much stock in is that ice water is any better than room temperature water for quenching. I leave my bucket out by my oven all summer long and just add to it when it starts getting low. Never saw a hardness difference no matter what. When I took a little community college machining course we HTed projects we made and just quenched then in a 35 gallon barrel of water they had sitting there, no ice involved. I've wondered if ice water would lead to a bigger vapor barrier around the bullet when first dunked and lead to soft spots and lower results but never wondered enough to try to find out because my system works for me.
Maybe hard bullets aren't best for every situation but up to this point I haven't found one. I either water drop or HT every bullet I shoot and have no problem. There's no way in hell I'm going to sit around for 2 weeks waiting for air cooled WWs to harden when I can either mold quench or oven HT and be shooting them the next day at velocities from 750 to 2600 fps. Not enough patience in my persona for that. For the 6mm I'd have to believe that the harder you can make the bullet the better off you'll be.
Finally as you've found out you don't have to sit around forever waiting for the bullets to get hard using either type of HT method. Overnight will do it just fine. I've read people suggesting that it takes up to 5 YEARS for a Hted bullet to reach full hardness which is a heaping pile of BS. I've cast and HTed bullets on a Friday morning and had them at the range shooting them at 2550 out of my 30x47 on Saturday. I have both an LBT and Saeco hardness tester so I know they were plenty hard.
Heat treating is just like everything else cast bullet related. Simple as can be made complicated by people who like to make a science project out of changing a light bulb.
Bill I don't know what 6mm cartridge you're shooting but when I was shooting my 6.5 PPC the thing wouldn't shoot without a P-Wad. A load of 4350 with the P-Wad shot about 1700 fps out of the 8 twist barrel and did alright. I was using a 170 grain bullet though.