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Different bore sizes on the same gun

Posted: Tue Jan 20, 2009 4:28 pm
by Silvers
I measured the barrels on a 20 gauge SW today. Right tube .624" bore with .030" wall at 9" from the muzzle. Left tube .617" bore with .025" wall. The outside diameter (O.D.) of the tubes are different, right tube has a larger O.D. at the 9" location than the left one does. If the right tube was honed or backbored the walls would be thinner, not thicker. This leads me to believe the assembler reached into the bin and came out with two tubes with different mfg. specs. Or maybe something like a 1 weight and a 3 weight were assembled together. Has anyone seen anything like this? Silvers

bore sizes

Posted: Tue Jan 20, 2009 5:30 pm
by THE FOX
Silvers, I am wondering if it is a late Savage era gun. It seems that there was some drop in quality in the last years, as they were actually assemblying parts that came with the company when it was purchased. Bryan

Posted: Tue Jan 20, 2009 6:10 pm
by Silvers
No it's a mid-20's Philly gun. The more I measure, the more convinced I am the gun has two different "weight" tubes. Incidentally, there are no markings of the bottom of either tube, neither weight stamp nor manufacturer ID letters. Silvers

Posted: Tue Jan 20, 2009 10:14 pm
by FRBRIT
Frank,
I have a similar gun as yours. It is a mid 20's 20ga in which the bore I.D. sizes don't match with .010 difference. The choke tapers are the correct length and taper all the way to the muzzle with no parallel section in them. I've been wondering the same thing as you. I've sent off for a Callahan letter and I hope it tells me if the chokes are correct. As it stands right now the chokes are only two points off from each other at IM/IM.

My suspicious side tells me that possibly the one barrel was honed for some reason,but who ever did the work did a great job of not altering the original chokes. Then again I wonder how close the QC and factory tolerances were back then and if they occasionally let one slip out of the factory this way. After all how many customers back in those days would have had the instruments to measure such things or who would care as a buyer like we do today.

Posted: Tue Jan 20, 2009 10:34 pm
by Silvers
Hello Paul, thanks for your reply. This 20 gauge is choked .016" R and .022" L. I haven't patterned her yet but she'll probably do Mod and Imp Mod percentages. The choke tapers are proper with no parallel section at the muzzles. With .624" and .617" bores I'd probably be thinking the right barrel was honed or backbored but the wall thickness and outside diameter measurements suggest a different profile barrel blank was used on each side. Frank

Posted: Tue Jan 20, 2009 11:30 pm
by AmarilloMike
Both my Foxes have matching bore diameters. The XE sixteen doesn't have the barrel weight code.

There were probably times they were out of the right size tube and just had to make what they had work. Not the optimum but at least everybody got to keep working that day.

Best,

Mike