I noticed in the newer reference photo that the slotted bolt is deeper in the flash hider than I had realized, so I counter sink the hole a little more.
Before moving forward with the piston half installation, I need to expand the piston half bolt areas using a 1/4" end mill. Here's a before pic:
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The expanded area is toward the the "grill" area of the piston half. I think the reasoning behind it was to get enough room for the 1/4" diameter bolts that were used. With the pistons machined, I use the reference photos to get the bump placed in the correct spot. Although the bump is placed different on both Bunker blasters, after looking at the MoM blaster, I noticed a pattern: All the bumps are centered within the mount area, so this is how I place the bump:
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I'm not working with a rubber bump, so I use my belt sander to create a step at the bottom of the bolt so it sits flat on the Mauser:
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I use some contact cement to attach the bump and super glue to attach the piston half. I use 220 grit to sand the areas on Mauser where the parts will sit, and then the parts before placing them:
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I noticed in the newer reference photo that the Phillips head bolt appears to be completely flat. It's very difficult to tell if the bolts are flat on the left side of the blaster, but since all of the bolts used on the blaster were counter-sunk into place, it only seems to make sense that this is how it was done on the left side. Here's the newer reference for the right side. Notice that the bolt for the piston half is completely covered in dust:
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And the left side:
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Both parts are drilled, tapped and counter sunk. Here's the Mauser with the bolts installed:
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