As said it is obviously bottoming out before being fully tightened and compressing the gasket.
I imagine in the past someone had a leak so they tightened the RC down so tight they distorted it, and it then had a skim, where someone was a bit enthusiastic about how much he took off.
If it were the studs being wrong and too long, you could simply cut them bit I think this is very unlikely to the the case.
I have a RC in my garage so can easily measure it if you want, just PM me.
Whilst the RC is off I would stick a bit of sealant under under the front cam caps as they leak here often.
I only torque mine down to the correct setting and it is fine with a cometic gasket, plus a dab of sealant under the front caps, and a little just to hold the half moons in place, plus around the rear half moons.
tabetha