I find myself in need of expertise. Today the Parker GH 16 ga. arrived from Griffin and Howe. I assembled my wall thickness gauge and took a lot of readings, over and over. The gauge rods flex, so it takes good technique to get accurate readings, thus the desire to repeat. Wall thickness is up to .006" below the recommended minimums I was able to find. I believe that those figures were for 10-12 ga. guns, but have no separate list for 16 ga. In theory, the smaller the bore, the greater proportion of wall to bore/ surface area is, but how much difference it makes I am unqualified to put into reliable numbers.
Overall the gun is in very good condition, even if the barrels appear trimmed at 27 7/8". Listed as I/C & Mod, but choke measurements show Cyl. & Mod. Top lever is far right of center and condition of the gun indicates minimal use. Bores are .663-.664, shiny with just a hint of frosting. Honed? More likely just polished at some time. Barrels may have been refinished long ago, edges are not rounded off anywhere but there are two vent holes on the bottom rib, one on each side of the forearm lug. That tells me someone was worried about draining chemicals and etchant during a refinish.
The area of concern is along the bottom joining rib. Chamber and forcing cone measurements are pretty uniform around the circumference. It's further down that things get eccentric. Looking at the muzzle end, it appears that the tubes have always been that way since the eccentricity continues between the barrels and not just along the rib. Measurements, minimums:
Chamber/forcing cone jct.: R .095"/ L .087"
End of forcing cones: R .107"/ .106"
9" from breech: R .039"/ L .042"
12" from breech: R .026"/ L .033"
9" from muzzle" R .019"/ L .023"
As I take measurements further around the circumference from the bottom rib, thickness increases noticeably, by .010" or greater. I'm curious what Drew (sent you an e-mail) and others with more experience evaluating situations like this think. Useable or lost cause? My intent is hunting with mild loads.
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Parker GH 16 Damascus-wall thickness
Threaded Mode