For those with a few extra bucks, high tech could be a way to go? Not all gauges fit the job but some do, watch out for minimum measurement values in the spec.

http://catalogs.indiamart.com/produc...ss-gauges.html

:duck: Before I get dragged over to hot coals, I admit I don't expect anyone to think this is a good idea. I'm just pointing out that there are alternatives although not necessarily a good one.

Robin,

I think it is a great idea. I looked into these about a year ago and stopped when i saw the pricing. If money is no object, for $1K to $2K you can get set up to do a super job of measuring barrels. Some models have a scan feature, track min and max thickness, data logging, etc. Way high-tech.

Don't forget you will be measuring metal tubes and special sensors will be required. Most are designed to measure flat stock and since you are dealing with ultrasonics, the contact area is critical.