I have a MM211 and love mig welding, but I'd like to get better with the oxy-acetylene. I hope some people here have some experience with the gas. I'm have a problem with flashbacks when the torch pops and squeals. This is the result of the flame backing up in the handle. It happens just about every time the puddle starts to form and I start adding filler. I'm welding 1/8 steel with a #2 tip, neutral flame, 4psi acetylene and 5 psi oxygen. Everything seems right this doesn't make sense. I don't know if there's something wrong with the handle. I don't have any problem while cutting. Has anybody seen this or have any suggestions? Thanks