I typically can get my infinity up to around 250 without much trouble, which tears through anything. Tough to get it much higher than that.
Last night, though, I got lucky and got it up to 397. It was hilarious- gun was firing too fast for the game to animate all the shots.
Oh, and I was using Gaige and Anarchy/Close Enough and equipped the Bee/Badge. I got her Anarchy stacks up to 450. It was pure comedy gold- I could just fire randomly at scenery and enemies nowhere nearby would be insta-melted.
lol I think I figured out on my own there are 2 types of explosions, one is larger and makes a different noise, that is the only one that will power up your other gun, so in order to make them stack you need that same explosion multiple times in a row. otherwise your gun resets on the normal explosion or normal reload.
The Smasher has a 10% chance to trigger a x2, x3 or x5 bonus on every reload. Everytime you switch/unswitch to reload the smasher and there is a chance a new explosion will go off and add another 10% chance/stack (this is a glitch obv.). So the first reload -10% explosion triggers- (switch weapon) -now there is 2 10% chances for an explosion in play- (keep doing glitch till next explosion)- now there are 3 10% chances etc. When you get to 10 stacks the odds suggest one explosion should go off every reload. When you get to a 100 stacks you can reasonably expect that around 10 explosions will go off every reload.
Bonus stacks are additive. If you get the expected 10 expolosions at once with the previous example then you will have anywhere from a 20-50x damage/ammo/fire rate bonus. Switching to the smasher does not end the glitch, and reloading it again just makes the game recalcuate your bonus, which could be higher or lower depending on your luck.
The reason that you think there are different types of explosions is that the sound and visual effects play for every explosion that triggers, so if 10 go off at once it will be much louder, the explosion will be much denser looking and it will lag your game.