I’m playing a ranger character who’s in this cyberpunk campaign. Me and the DM agreed that my character (I’m gonna use Kael because it’s easier to type) can use the Automatic Rifle item stat block as a sniper. He also wants us to have pistols so I have the automatic stat block for that. Here’s the thing. I have a +5 to dex, that with profiency gets it to plus 10. Without proficiency it gets it to +7. On the pistol (without proficiency) it still has a plus 10. At level 5 Kael has a PB bonus of +3.

So if 7 (Base) + 3 (Pb) = 10, how does 10 (base) + 3 (PB) = 10? 

This is just a small thing I noticed and has been plaguing my mind for an hour now.

It may be due to how the Archery Fighting Style gets factored in..

Maybe, it’s probably that fact the pistols a martial weapon. 

Since it’s a martial weapon, and rangers are proficient, the correct formula is 5(dex) + 2(FS) + 3 Martial bonus. So that’s why it doesn’t change at all

Yes as Ranger you have proficiency with a Pistol allowing you to add your proficiency bonus to the attack roll for any attack you make with it for +10