Can be done with a hacksaw, but need to have good sharp blade and good control over the saw. Use two hands on the saw one on the front and other on the handle. Slow cutting motion, keeping eye on straightness of cut. Cut several mm longer than desired. Have a line marked all the way around the leg and judge cut by the line. If going off line, turn blade 90 degrees and start again. Eventually you will get through the leg reasonably well and take a file to make it straight. I have done all my tubes this way with good results.