I'm waiting on a mag tube extension for my 870. I do not have a barrel clamp of any kind yet, and I was wondering if I could use something like this eBay part: LINK HERE The biggest consideration, I'm almost certain, is the measurement of the gap between the barrel and the extension. The last thing I want to do is install something like this & bend the barrel or screw up the mag tube, and I'd rather not have a clamp and one of these... seems redundant. Has anyone used a part like this? I'm not looking to add a ton of tacticool gear, maybe just a flashlight.