[8.50] half firing rate

[k-bones]

I had 3 guns of same range (750) - 2x fan of knives and 1 plasma wave. While destroying some towers on the sidelane, they were firing 2 times slower. Happened a few times in the same game, and I noticed that it stopped always when I came a bit closer, so I think this occurs when you're exactly in range.
Btw the torpedo also happens to jam (at different distances)... is the cooldown put before or after each shot?