Do you even need grooves?  We make several products using through-hole components that are intended to mount using VHB double-sided foam tape.  The boards are 0.062" thick double-sided with PTH and we use a table-top vertical belt sander to bring the component leads almost flush with the solder mask.  In other words, the solder mask isn't touched by the sand paper but the leads are all sanded flat and sitting just proud of the solder mask.

This works well for small boards.

For what it's worth, there are commercial machines available that use a rotary saw blade to do the same thing.  The board is held horizontal in a mounting / clamping system on the base and the saw motor is vertical on a sliding X-Y mechanism.  The saw blade simply cuts all of the leads almost flush with the board surface.  

This system is suited for boards of all sizes but especially for those boards larger than can be handled easily to be sanded with the belt sander.

Also note that these techniques are suitable only for PC boards with plated-through holes.  

Maximum protusion length for through-hole component pins
To experiment I started a bot game, toggled invincibility and let the bots attack me. There were two clear hit effects: a major one that tilts view up a lot and sideways and a minor one that only tilts it up.

So I tried releasing single shots exactly at the tilts: during a major one a single bullet ended up here (slightly covered by text). Actually the crosshair never moves that high so there tends to be a good amount of additional upward deviation of single shots fired.

But when single-shooting during the minor tilts the marks seemed to end up exactly at the location of the crosshair.

Now, when switching to spraying while being shot this pattern emerged. This was mostly caused by the minor tilts and, I guess, "standard recoil". Occasionally a major tilt caused a single bullet to lie severly outside of the depicted cone.
