I have a single burner forge about 13 inches long, I'm unsure what you mean by size of burner but mine is relatively small with a .30 might tip for propane dispersal. I typically can judge my forge based on a little bit of experience with it, like the sound and color inside. I believe the lady meant no harm by what she was saying, she came from a propane background and I believe she was indoctrinated with give no advice that could lead to trouble for the company. She was actually very nice, but had no experience with propane forges, clearly. I may go to a two burner forge in the not so distant future. I would like to see if forge welding smaller bullets is possible in this forge is possible, but I understand it may be a stretch. Thank you guys for your helpful comments!