I've seen several cases of extensions without clamps being knocked off the gun by a bump.
The most serious was a small-town police chief answering what later proved to be a false robbery alarm at a local bank.
When he arrived at the bank, he grabbed the 870 shotgun from the car's rack and stepped out.
As he stepped out, he bumped the extension on the car's door frame and the extension was knocked off.
It was blown off the gun with such force, the windshield of the car was broken.
I'll never forget the Chief's face as he told me about how he felt when he found himself facing possible multiple armed holdup men with nothing but a 6 shot revolver.
How strong and sturdy an extension is doesn't matter.
The extension could be a solid steel bar.
It's the GUN's magazine tube that's the weak point.
The tube is fairly thin metal, which is further weakened by the deep, square threads.
Give the extension a bump, and it can either be bent out of line, or knocked completely off the gun.
Invariably, it isn't the extension that gets damaged, it's the gun's magazine tube.
In the case of the Remington, this means the gun has to be returned to the factory for an expensive magazine tube replacement.
In all cases, it's means your shotgun is out of service, then and there.
About the best barrel clamp ever made is the Remington factory.
Uncle Mike's make an excellent copy, which comes complete with sling swivels.
They make versions to fit several brands of guns.
http://www.butlercreek.com/adtempla...y=1279575&subcatky1=4548843&subcatky2=2000180
Extensions knocked off guns is not as rare or unusual an occurrence as you might think.
Bottom line: There are NO good reasons not to use an extension, and several good reasons to use one.
