GUN RUN UPDATE: Just found out the Reiterpallasch is a sword. I think I might have missed it the first go-around, or more likely just never used it. Not sure why the guy has that included in a gun-only run, even if it's just for parrying. I thought it'd be a mainhand gun that I could parry with, then fire my actual damaging gun. Nope, it's a sword. A sword you can parry with, sure, but I don't think it should be usable in a gun-only run so I immediately shelved it.
Entering the second half of the game now, my main issue is still the Repeating Pistol running out of ammo so quickly (even with liberal use of blood bullets). I just got Evelyn from Cainhurst and I like the feel of that one more than the Repeating Pistol. Only fires one shot, does a lot more than 50% of the damage of the RP, so I'm doing more damage overall for the amount of shots fired.
In other words, if doing a gun run, my advice is: Go from Hunter Pistol to Repeating Pistol to Evelyn (rather than sticking with the RP). Can get Evelyn as soon as you can reach Cainhurst.
Unfortunately I used up all of my tier 1 and 2 upgrade materials on Reiterpallasch before I decided to stop using it, and I used a Blood Chunk on the RP right before I got Evelyn and realized how good it is. Wish I had all of that back so I could +6 Evelyn right out of the gate. All I've got is +3 now since tier 1 materials can be bought. Luckily I didn't use any more Blood Chunks. Now I need to go farm Twin Blood Shards for a while, get Evelyn +6, and blast through the rest.
I imagine the second half of the game will fly by compared to the first (which took 12 hours). Also realized that I like the first half of the game a lot more than the second. The atmosphere and fire-like orange glow on everything are amazing. Once everything turns to night, it's harder to see and significantly less amazing-looking IMO.
EDIT: Nevermind, you can trick-weapon Reiterpallasch into a gun. Didn't think of that right away because this is a no-weapon run and I haven't played in years so trick weapon transformations are a distant memory. Since you only use Reiter for parries, you don't need to level it up and are better off using the Cainhurst/Forest upgrade mats for leveling Evelyn. Any extra mats can go to Reiter, for sure.