doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Proof question on a J.F. Smythe 20 gauge

I am trying to figure out the proof marks on a 20 gauge J.F. Smythe(serial 21855). Dual triggers, light scroll engraving and round knob stock, for those who are concerned about such things.

Rib Marked: J.F. Smythe Darlington & Stockton on Tees
Marks on the barrel flats:

Left (measured .028 choke):
Script entertwined BS under crown (above barrel flats)
Crossed halberds with v at bottom
Crossed halberds with p b c
Diamond with 20 over c
21 (nothing around the 21)
Choke

Right (measured .009 choke):
Same as above without choke

I think it is black powder proof only, made between 1904 and 1925, but I wanted to check with the experts. Barrels appear to be fluid steel, not damascus. I thought the 21 markings may indicate the year of manufacturing.

Am I close in reading the proof marks?

Thanks for any additional information you can add.

The 21 is an indication of the true bore diameter, not the year of production. It means that the gun is slightly underbored. Standard 20ga bore diameter is .615, 21 is .605. If the bore currently measures .615 or greater, the gun would be out of proof under the British rules.

The word choke means that the barrel in question has more than a minimal amount. Surprised that the R barrel isn't marked choke as well, because .009 is enough to warrant the choke mark.

The V mark is for view, from the proof process. It was no longer used after 1904. 20 over C in a diamond came into use in 1887, so I think your gun is from the 1887-1904 period. And it would appear to lack nitro proof, because during that period it would have had either the maximum load data, or else the words nitro proof plus the shot charge and the word maximum. Also, if it were post-1904, the V mark would be absent and you'd see a BV under a crown (not script, easy to read) instead.

I'm guessing that what you're seeing as a BS under a crown is actually a BP, which would be a correct Birmingham proofmark from that period.

Looks to me pretty much standard marks, 1887-1904 period, with no subsequent reproof.

What Larry said, plus, the .009 thou choke in the right could be from boring/honing in that barrel and the .028 is pretty stiff for the left which may indicate the same.If considering purchase, checking the bore sizes and wall thicknesses should be your next step. IMHO

Thanks for the additional information.
It sounds like someone honed the barrels significantly. There appears to be plenty of thickness left throughout the barrel, but i won't know for sure until I get a bore gauge.

4 1/2 inches past the breech bore is .626 right and .629 left(the numbers I used to determine choke last night). 4 1/2 inches from the bore end is .619 right, .617 left (this would yield chokes of .002 right; .016 left)

I can only reach 4 1/2 inches with the i.d. gauges I am using. I will have to get some better equipment to check wall thickness.

I got it at the right price. I'm happy just to have the action to learn gunsmithing on, even if the barrels end up scrap.

You need a wall thickness gauge as well as a bore micrometer. I'm not quite clear on your bore readings, but choke probably would not extend 4 1/2" back from the muzzle.

Sorry, I said bore twice. I initially measured 4 1/2 inches past the chamber (because it was easier with my gauges)and got the larger numbers . Mesuring from the bore end (and pushing the gauge through the chamber) resulted in the smaller numbers.

I'm using an old style telescoping gauge which can lock. I then measure it with calipers. There is plenty of room for error, but it is what I had on hand.

I think pits were honed out of the barrels and the area just past the chambers was the most pitted and therfore got honed out the most.

I will have it measured with a bore gauge and a wall thickness gauge before thinking about firing even low pressure loads.

If you could only reach 4 1/2" in from the rear end, then chances are the bore was still tapering down some. If you reach in twice that from the breech end, that should give you pretty much the same bore diameter reading you'll get reaching in 9" from the muzzle end. But if the readings you got from the muzzle are accurate, then it's out of proof as a 21, and fairly extensive honing has been done.