I've inherited a UDS from a friend who's team member had to move across the country for a job. They used a bunch of these in competitions, and supposedly won a competition or two with this UDS...so I'm assuming I'm not using it right!
I have bear paws for hands and I put about two double-handed grabs of charcoal briquettes (Kingsford) in the basket. End pile is about 5-6" high and maybe 8" wide. I start it with fluid (I know, I know...but I can't taste it) and put it in the barrel to warm everything up. There are three 1" holes, two are threaded/capped and the third is a ball valve....I open all of them and let the coals get white. I'll throw my wood on the coals (mulberry and cherry), meat goes on top grill, and I put the lid on. The barrel had a threaded hole, maybe 3" or so that they fashioned a electrical box cover to regulate the exiting smoke. The gauge is on the lid a few inches from the hole in the lid.
Leaving it like that, it'll last about 2-3 hours and will only get up to 220-230. The last time I played with it, I got it up to 260 by cracking the lid a 1/2". Talking to my friend, he keeps giving me funny looks when I tell him my temp woes...saying they all have multiple barrels and never had this problem. My last attempt, I smoked a 2lb boston butt for 4 hours with temps fluctuating between 210 and 260...mostly around 220. I had to finish in the oven.
So I'm left wondering if I'm not using enough charcoal. If I'm not using the right charcoal. Or if I need to add more intakes and another exit. I'm going to have another round of boston butt this weekend with my parents and would like to get closer to solving my problem.