The problem with the 30A, like most of the Marlin models, is that they DON'T USUALLY HAVE A SWIVEL STUD ON THE FOREND!!! Whether they're a clamp-on mag tube type (usually aftermarket) or mounted on the forend tip, the Marlins just don't offer a level surface around their swivel studs that would allow you to mount a bipod.
If you have the clamp-on mag tube mounted swivel stud, you can usually slide it forward to make room for the bipod, but there isn't enough tube diameter for it to be stable.
If you have a forend cap mounted swivel stud, it's not level from the barrel to the forend cap to the forend wood, so the bipod will mount, but the legs angle forward severely, and hit the muzzle when folded...
So, what's a guy to do?
MAKE A SHIM!!!! (Or send me a PM and we can figure out how to get you one) The pictures below are of one of my rifles and shims for a forend tip mounted version, but the same idea works for adding stability to the bipod even for a mag-tube mounted swivel stud. For mag tube style, I add spacers to leave a relief for the swivel clamp, and build a "trough" that blends the small diameter of the mag tube to the flatter shape of the bipod mounting frame. You can see how the trough in the top of my shim has a tight curve to fit the mag tube, but the bottom of the shim is rather flat to mate up to the bipod. I accomplish that by skiving the intermediate layers of leather down to make wedged shims.
Here's a picture of one of my Marlins with one of the shims I've made and a knock off harris copy bipod.
This particular shim is made from leather, but I have done them from plastic block as well. The advantage of the leather is that it's non-marring to the finish, and remains flexible enough to avoid breakage, but rigid enough to provide a solid platform.