Is that 4.3 max load or recommended load or ?
Me personally I'd back off that 10% start out at 3.9ish load up 25 then go a little moreand make 25 and etc.
Once I got good reliable cycling I'd consider that my base load, and then go hotter if I wanted velocity or was looking for greater accuracy or whatever.
Me personally I like the soft loads. I shoot them better with less wear and tear on the wrists. I started out wanting loads similar to factory crap, for some reason.
You got good advice above. I shot a bunch of squibs before I wised up and got a little light to shine in each case. I tape one of those flex head $3 lights above the bullet seatnig die. Works for me.
I'm sure you're smarter than me but it took me a long time to figure out what I was doing. The big things are *don't double charge* but even more than that, if you fire and don't strike the target, or it doesn't cycle, or powder falls out of the chamber LOL(done that!), or you just have a hunch, check the barrel to make sure there's no bullet lodged in there. I just do a quick field strip and hold up the barrel. It's much less embarassing than blowing up your gun! :-)
It took me a long time to get the hang of it, and I just realized today that I loaded up 1000 bullets with too light a charge!
Oh yeah, that's another thing I always forget, don't load up a million bullets until you're absolutely sure of the load. I've got thousaands of rounds kicking around here that I no longer like the recipe, but only decided that after I made a ton of them. Live and learn.