I think requiem_for_a_starfury has given the truth and jarekfall has put the ideal method to add the modes.
But will every Charactor can have this mode?
there are many charactors in the BOS, change the spr will be a hard work. May be you think "human using only" should be fine, but that's seems not reasonable in the game.
Easy to get this, create a special scope which been describe as "one important part of AT4", in the inventory, it shows as a scope, but in the hand, it change the image----- a full view of targeting in the scope , with red or blue color......ya, blue color is better...... indeed, it is not a scope item, it's a rocket launcher with scope image, then change one type ammo's element and image into rocket element and AT4 image(the ammo you dislike, for ex. the fucking acid...), so only At4 can use this scope....no, only the scope can use this AT4,ha
It's reasonable, easy and show cool!
when you fire your AT4, first put on the scope......in your hand, just imagine it's on your AT4 or your eye, then fire your AT4(haha, it is only a kind of ammo), for its ammo element, you can see your AT4 is fewer and fewer in the inventory. If your like, you can put the AT4 in the other hand, use the scope to targeting and shoot. Every guy can use it, even mutant...
The easiest the best, with best idea, for the best army products.
Do you need the special scope SPR? Call me, order now! for best price!