I stumbled onto a used 18" barrel with night sights at a local gunshop. The tritium had faded mostly so I picked it up for about $40. I still have my old full length barrel also. Sometimes you get lucky!
I shortened mine with a new sharpened pipe cutter, did a darn good job. The trick is to go slow and let the cutter cut a little at a time. Use cutting oil. Then clean up the cut edges with swiss files , stones and 400 wet or dry and cold blue it.