When you place blocks they get eaten up by a SMG, my suggestion is drop the blocks entirely from the game and instead add in dedicated coloring/ health blocks.
i.e.
20 concrete blocks, can take 15-20 hits
30 Sand Bags, can take 10-15 hits
or something else like that, instead of blue/pink blocks (which are funny) that take 2-3 hits from an SMG and you're dead.
I'd honestly like to spend time building a WW2 style bunker, have it look concrete, have it matter, and kill people from it.