They were 5 on a clip for £17 and were grotty but I've put one on a .55" bar and placed it in my lathe chuck, spun it on a low speed and carefully scrapped the crud off with a broken parting tool. It's come out very well and by the time I've machined up a dummy projectile out of stainless I doubt the laymen would ever know it spent 30 years at the bottom of the sea.