I have the 550B mounted without the strong mount. I bought 2 different lengths of bolts due to the differences in the thickness of the press base (not required but I wanted as little as possible bolt length poking out the bottom of my bench).
The front thickness of the press is about 1/2" and the rear is about 1". If I remember correctly I used 1/4"-20 hex/lag bolts. You'll also want 4ea. flat washers on top, and 4ea. "fender" style washers on the bottom under the bench. Also 2ea small wood or machine style screws for mounting the ejected cartridge bracket (don't know the size on those, just looked around till found some that did the trick)
Take your bench thickness (~3.5") + press thickness + at least 1/2" extra for threading the nuts/washers on the bottom. Given all that, I'd would say you want
- 2ea 1/4"-20 hex bolts at 5" length
- 2ea 1/4"-20 hex bolts at 4-1/2" length
- 4ea 1/4"-20 nuts
- 4ea flat washers
- 4ea Fender washers
- 2ea small wood/machine style screws
Check the Dillon site - "Dillon Universal Mounting Hardware Kit, stock number 14355" for a visual of their kit. Or could give them a quick call to confirm. Have fun with your new press!
