I've been doing some looking into my next gun purchase and I've always liked the looks of the Ruger guide gun. First of all does anyone own a guide gun and second what do you think of the 300 RCM cartridge?

short, loud, heavy with inferior ballistics and a proprietary cartridge.  no thanks.  ymmv.

I really like ruger rifles, that said I would stay clear of the RCM cartridges.  They don't buy you much of anything and are hard to come by.  If you really want a short action look for something in the WSM line like the .300WSM.  If your really sold on the guide gun in a .30 cal I would just get a 30.06 version.  The 20in barrel is too short for the .300 win mag.

What are you looking to do with this rifle?  What features does the guide gun have that you need to fill the role for its intended purpose?  Asking so maybe myself and others can help point you towards other models or brands that would fill that role.  The guide gun is pretty spendy for a just because rifle, if you have the cash though get whatever tickles your fancy

I dont see much of the .300 RCM but we have 375 Ruger on the shelves here. I want a .375 Ruger Guide gun just because but I'd handload for it if I ever did get one so availability wouldn't be a problem.