Aiming.
Holy crud whatever happened to my aim of long ago, it isn't there now. I have to have one spray weapon (Shotguns mostly disappoint me now, but I can go with a Peacekeeper or a double shot Mastiff in my optimistic moments), and actually I like the Prowler best because if I'm short range, sometimes I just can't hold down the trigger and keep it in line. Often, too, snipers are wrecking me if it's a one shot and long reload like a Sentinel (but I'm still going to break out a Kraber if I can find one).
The R-301 really is the premier assault rifle, but I prefer the Flatline. At least if I hit, I do damage. Sometimes I'll have to just only go single shot mode on the R-301 not because it's the best mode all around...but because I'll crack off a bunch of misses and it's better if I still have some bullets left.
You can forget guns like the Devotion, which is hard to use already, but for me, I'm just looking at the sky with it. Too bad because it is stupid fun.
I prefer the 30-30 too, but I'm just not that good with it. Sometimes if I have the Flatline, I'll tow a 30-30 around just to have a laugh and launch off some arcing shots.
Believe it or not, I'm best with a bow. Again, because just one shot. But the bow kind of doesn't do enough damage these days.