I am installing my 1/2 engineered with a Bostic M111FS. I am getting staple detents, but not all of the time. Probably only 5% of the staples cause something that can be seen on the surface. Still, if I can eliminate it I'd like to. Here are some pics of the worst one...







Any idea what is causing this?

Are you using the 1/2" plastic spacer that is supposed to be used? It has a relief cut where the face plate contacts the flooring. Make sure that is NOT contacting the flooring. Plus, if you hit the nailer too hard, you can cause damage to the edge of the boards. A light rap with the mallet should be all that is required to fire the staple.

I am using the spacer, but added a layer of roof felt to it to tweak the relationship between the tounge and staple.

Since you mention it, I suspect it might have to do with how hard I am hitting the stapler. I'm not wailing on it, but I'm hitting it harder than a light rap for sure.

You may be using too much ammo on that 1/2" engineered. A 15 ga. staple may cause a slight dimpling effect too. I suggest you stop for a minute and let the light reflect and see if you are getting those slight dimples. You can't feel them but they show if the lighting is just right.

Does the manufacturer say to use the M111FS? A stapler made for engineered wood like the Spotnails that uses an 18 ga. 1 3/8" long, 1/4" narrow crown fastener may work better. It has foot plates for 3/8", 1/2" and 9/16" flooring. I just recently got one and it works quite well. just pull the trigger.

The pictures are of the worst spot, and it only shows up in the right light. Most of the staples show nothing - only 5% or so have any problem, and even it is very slight. The manufacturers literature says to use cleats, but since the consensus here was that staples hold better, I called and asked their tech support about using the 15ga staples and the M111 and they said it would be fine. I have a Porter Cable 18 Ga stapler that I used on the first row where I couldn't get the M111 and it seems to hold fine, though it would be a lot more work since it is not a floor stapler and thus requires hands and knees and precise alignment.