from "NPCs" thread
I wish there was a way of using weapon REL as the trigger for jams so that they happen purely randomly whether you push your roll or not. Practically every RPG has some sort of fumble mechanic for this but in T2K 4e fumbles seem kind of voluntary. In another thread someone was querying the point of pistols. Stoppages at the worst possible moment are precisely the sorts of situations that make carrying a side arm worthwhile. The mechanic for jams also doesn't really sit well with the weapon descriptions and stats. The M60 is described as being prone to jamming and has REL 4 compared to the REL 5 of most other weapons but the mechanics of the game don't really make it jam more often, they just make it completely break more quickly.
That is true. I've wondered about that particular rule change a bit, but even before it, jams had nothing to do with your weapon reliability. The only sorta-easy change I can think of is that if you ever roll mishaps equal to or more than your current reliability, you get a jam, whether you pushed or not. That's only likely to punish people who let the reliability get down to 2 or 3, but it does at least put a weapon with a lower overall reliability ceiling closer to there all the time. And who knows, if you're firing high ROF a lot...
Anything else I can think of becomes exceedingly complex.
My solution for the above issue would be - "if a player rolls two or more Mishaps in a regular roll, without pushing, a Reliability Roll is made with a single die to see if the weapon jams. To avoid a jam, a player needs to roll a success on that die. A d12 die is used for Rel 5 weapons, d10 for Rel 4, d8 for Rel 3, d6 for Rel 2, while Rel 1 weapons jam automatically."