tape for me too. I did look at these when I first saw them but as I had a .243 & they were only recommended for 7mm & above they weren't of any use to me. You're also adding a plastic disc to the environment unnecessarily.
I learnt the hard way, first ever stag, i got a bit excited, pushed rifle through hole in hedge and plugged barrel in mud, luckily the stag was very patient as i sucked the mud out and shot the stag!
Bog standard electrical tape, never comes unstuck, i don't use a mod, so its a couple turns for grip around the barrel, 1 strip covers bore, then wrap around that piece onto barrel.
Blew a piece off this morning!