I usually have my barrel covered, though I forget sometimes. When packing in, my rifle is usually strapped in my pack barrel up. That means leaves, pine needles, bark or anything else can get in. I have got to camp before after going under a few trees, and seen a pine needle in the middle of my barrel. When I see a lot of people occasionally talking about missing their first shot for unknown reasons, I sometimes wonder if they had a small bore obstruction, not enough to cause a major issue, but enough to affect impact. I know in my testing, that electrical tape will affect the first shot in every gun I have checked at longer range. On my normal barrels, I use balloons or thin plastic wrap, or if all I have is tape, I will tape it but remove it before I take a longer shot. We put covers on our suppressors, partially for safety, but in large part to prevent extreme mirage from occurring after a couple shots while practicing, or if multiple shots have to be taken while hunting. So in this case, just have the cover barely in front of the can, and cover it with plastic wrap and a rubber band, won't melt to the can because it is protected by the cover, and keeps crap out of your barrel. Just a couple of drops of water in your bore from a light drizzle can cause some issues you don't want.