tl;dr version:
Make repeating crossbows hold five bolts per clip, unless you get that as you gain levels.
I recently got my rogue the Master Mechanic prestige enhancement, and quickly discovered its biggest benefit: proficiency with repeating crossbows. Sure, these things plow through ammo like it's going out of fashion, but multiple shots with one mouse-click, combined with a stat-based damage bonus (which most ranged weapons lack), turns this into a monster weapon.
There's just one thing, though. This crossbow fires three shots per use, and this doesn't sync with the way repeating crossbows work in PnP. Here's a by-the-book description:
http://www.d20srd.org/srd/equipment/...ssbowRepeating
This is backed up by the in-game graphic of these crossbows. The case attached to the bottom of the crossbow clearly shows four bolts, which -- when you assume that the thing is loaded and ready to fire -- means there are five bolts in place.
Does a character's stats (base attack bonus et al) affect how many shots are fired with one salvo? In other words, will my rogue get more shots as he advances? Or is it fixed at three? The DDO wiki doesn't mention anything about how rate of fire is determined, and the Compendium is even less helpful here.
If it IS fixed, is there any way we could get this adjusted to five? It would make it more closely match the original versions, and fix another headache -- odd ammo use. Since ammo stacks are limited to 100, this means that continuing use results in a reload of a single bolt. If a salvo fired five shots, then we'd have it come out even.
Sure, we'd plow through ammo even faster, but heck, I tend to buy plain bolts about 500 at a time.