weaver side mount question
 

I bought a Marlin 512 slugster that had the base already mounted. I bought a weaver ring setup. Is there supposed to be a gap between base and the mount? It doesn't look like the dovetail is even. I went back to see if the gun shop had another one, and was told I got the last one and it is the older model. It has the strap style with screws only on one side of the scope. This concerns me. The recoil is pretty vicious and I think rings with 4 screws would be better. So..... should I see daylight between the base and mount at the dovetail? I need this thing up and going soon. Any help is greatly appreciated.