This could be an interesting project...

[sirhrmechanic]

Old Sniper Shield C. WW1. Not hard to make... but bet it would scratch the living hell out of any bolt action you fire through it! But would make a nice display!

Sirhr

 

[Mister Ridge]

Wrap the front of the rifle in burlap?

 

[Lange Carabine]

Loophole is the proper term.
The rifles muzzle wasn't supposed to protrude through the hole.....