Can a CB Antenna Be Cut Down In Length and Still Work?

[DC]

I've got a Cobra 19 DX III CB along with a K40 CB antenna in my 2000 TJ. The K40 is a honking 55" long and when it gets whipping around off-road, it often contacts my hard top and rear windows and beats the hell out of them.

AFAIK, the very thin whip type K40 antenna is just a small diameter stainless steel rod with no wiring in the whip portion per se. If that's true, is there anything wrong with cutting the overall length down to say 36" and then having my CB retuned with a SWR meter? The reason I ask, is that a supposedly knowledgeable guy at my local Radio Shack told me today that it couldn't be done without totally ruining the antenna and thereby the performance of the CB itself.

If anyone has any knowledge about this (one way or the other), I'd sure appreciate hearing about it.

TIA,
Don