Here’s a quick guide from Paul West, gunmaker act London’s William & Son.
I was up at the James D. Julia Auction Company a few weeks ago looking over the shotguns in their March 11 & 12 sale. A lot of doubles caught my eye – from this great 16 gauge Woodwards O/U to this fantastic, 12 gauge J.P. Sauer Deluxe.
There were lots of nice American shotguns there, too, and I spent a while looking over the 20 gauge Parker and the 12 gauge Lefever shown below. Both guns impressed me with their crisp, original condition. Wanting to know about them, I looked them up in the auction catalog and I was shocked to see how thin the barrel walls were on both side-by-sides.
INCREDIBLE, ATTIC FOUND, 20 GA. PARKER BROS. AAHE WITH CASE. SN 161999 “It is absolutely original..Cal. 20 ga. 2-9/16” Chambers…Bbls retain 70 – 80% orig blue….Bore diameter: left-.617, right -.616. Bore restrictions: Mod, Cyl. Weight: 5 lbs. 14 oz…Wall thickness: left -.018, right -.020.
EXCEPTIONAL SPECIAL ORDER EARLY STYLE LEFEVER HEAVY GAME GUN. SN 16438. “Cal. 12 ga, 2-3/4″ Chambers… has 30”. Excellent, as found. Bbls retain 80 – 90% orig blue. Bore diameter: left-.732, right -.732. Bore restrictions: left – Full, Mod. Weight: 7 lbs. 9 oz. Wall thickness: left -.020, right -.016.”
Afterwards, I went back to both guns and took a long look at the barrels. After a lot of close looking, I couldn’t find any signs of repairs to the barrels. They had to be original. That means the barrels left the factory with those thin spots.
To learn more about bbl wall thickness and it’s importance, check out this article: Thoughts on Barrel Wall Thicknesses from the Parke Gun Collector’s Association. It’s interesting to see what people think today, and what the gunmakers thought back when they were putting these shotguns together.