Disclaimer I have one medium sized room plus hallway I'm doing in our home, so I broke my own rule and bought a cheap nailer, the harbor freight 99$ special. Material is 1/2" engineered maple Nailing down with HF gun and bostitch 15.5ga 1 1/2" staples. After a few runs I notice I'm fighting way harder than I should to get the boards tight. Looking at the fastener it appears to strike in the right spot, but blowing some of the tongue down out the bottom. Gun came with 1/4" and 5/16" plates. Running the 5/16. Any thoughts on what I'm doing wrong?

Chris in oregon

I think that you are using the wrong stapler. Does the manufacturer recommend using 15.5 ga. or 18 ga.? I always use the 18 gauge staple for one-half inch thick engineered flooring. 18 gauge staples come in one and one-half inch length.
An 18 gauge power cleat will also work to hold flooring down. Neither fastener will break the tongue on engineered flooring. The staples are only about a quarter inch wide, but won't pull out easily.