I did once test finger cots on a rifle that had no front sight to see if they made a difference in accuracy. I found no difference. But I was only shooting out to 75 yards with my White M97 in .451. I was shooting 80 grains of 2f T 7 and a 460 grain conical. I did find finger cots that looked to be still in tact. Why I am guessing the pressure of the air moving simply blew them off the muzzle.

A finger cot to those that do not know is a rubber bandage you can purchase at a pharmacy. Its used to roll over your finger, keeping dirt and grim out of cuts to the finger. They work real good. But in rifle, if you have a front sight, sometimes they tear, sometimes they don't.