If you have a Munro Hollower II then you probably have discovered that the Button Head Cap Screws (bolts) on the bottom are not the greatest. The allen head wrench hole in the heads strips out easily because the hole is to shallow.
If you purchased your Munro Hollower II from Steve Sinner at Advanced Lathe Tools then it comes with better Socket Head Cap Screws. The allen head wrench hole in these is nice and deep. However the standard height socket head cap screws are a little to tall. They stick down below the bottom of the cutter head. Some times they catch on the tool rest when you pull the tool out of a hollow form.
Low Head Socket Head Cap Screws work a lot better. They fit just right. See photo. You can get them from www.mcmaster.com. Part #92855A613 “Low-Profile Socket Head Screws, M6 x 1 mm Thread, 12 mm Long” $8.39 for 25 on 11/2018.
In the above photo the Button Head Cap Screw is the black one on the left. Standard height Socket Head Cap Screw is in the middle. Low Head Socket Head Cap Screw is on the right and in the bottom of the cutter head.
Note: The above only applies to the Munro Hollower II (or Hollower2). If you have the Mini Hollower or Wundercutt10 Hollower then you probably need a different size bolt.