To install these attachments, ensure that you have a screwdriver in your inventory, right click the MSR788 you want to modify, click on 'Upgrade' and pick the attachment you want to install.
Should the rifle jam on the player, press X to rack it and unjam it. The rifle will need to be racked after reloading. It can only hit one target at a time and can pierce through targets. The MSR788 Rifle is a bolt action rifle, utilizing a 3 round MSR788.