I did find with my other, smaller scope that I hit the rail with the bell before I got the scope back as far as I wanted it. For me, the rail could be a little shorter. Not a big complaint, but I don't have much need for it to be that long. I have my current bell within about 1/8", but when I put the temporary scope on I had it so close that I ran a dollar bill between it to make sure it wasn't touching.

The SWFA low mounts are the same height as mine, according to their spec sheet, but I think if you use them as a 1" ring, the scope will rest slightly higher. I'm not sure, as I've never used their inserts.