It isn't just a guard against rain. I tape my muzzle whether it's wet or dry. And wrap a back up piece around the barrel a couple of inches below the muzzle. A mis-step, for instance, can end up with dirt in the barrel that can end your hunting day. A pennies worth of tape is cheap insurance.
Came out of an arroyo,crawling,for a crack at a hog pronghorn one time,after a rainy/snowy day....pushed the 270 ahead of me and in classic, putzy fashion, managed to slip a bit and jammed the muzzle in the mud.....no tape of course so I slid back down outa sight.....
A pal and I managed to whittles a sagebrush branch down to size and scoop the crud out of the end of the barrel.We made sure it was clean....
I bellied back out, got a solid prone rest over a clump of sage,and killed the buck at about 275 yards....ever since then I always roll a couple of turns of electric tape around the barrel.Don't always use it but it stays all season.
