I am remodeling my house and installing engineered hardwood over a patched hardwood floor (my first time with Engineered). I am leaving the old hardwood and using it as subfloor as there are only gapped rough cut boards underneath. I don't think that a glue down application would work. I borrowed a MIIIFS from a contractor I worked with in college as we installed hardwood, but I am wondering is the MIII too much of a gun for my 1/2 in engineered. I like the idea of large staples and prefer that over the 18 or 20 gauge, but I can't seem to get the gun to nail properly as the tounge gets damaged. I swapped the 3/4 pad for the 1/2 pad, and I tried installing the finish kit, but I do not have the shims.

Any advice or suggestions?
Many Thanks - Daniel

Way to big IMO.