Previously I fitted them to a couple of Omegas (with no issues), but stopped when changing one out and the replacement Ox seemingly was slightly oversized (too long, wouldn't cock). It was in the correct packet, but I never bothered to check the overall length at the time or chop it down, so just removed it and fitted a (then available) Webley original. As has been noted on this and previous threads, if the spring is correctly sized for the gun then an Ox or otherwise will do the job (ignoring benefits or otherwise of cross section shape, steel type etc). I'm sure people wouldn't still buy them if they were that detrimental to a gun.