i believe the best way to cut open an oil drum is to use some method that doesnt create sparks. I always cut them open with my cheapy little harbor freight air powered sheet metal shear. All it requires is a quarter inch pilot hole and an air line. very neat very clean and in some cases the oil in th drum helps the cut move a little faster. Ive made probably a hundred Q pits out of 55 gal tranny fluid drums and havent had one explode yet.