Hi Baz. If you go to the Lee web site at www.leeprecision.com and look at the melter section mine is the production pot iv with 4" clearance. Like yours mine can be a bit tricky to get the temp just right but after using it for a while you get used to it. I certainly have to be carefull not to point the fan i use to clear fumes at it or it will go cool on you. I think if i was going to replace it i would probably go for the bigger 20lb model with the bigger element as this would probably be less prone to tempreture problems and i could get a few more big old .577s out of each pot full.
Take care, Tim