Every once in a while the gun buying bug gets me and this time I chose a Webley and Scott 700 imported by Abercrombie and Fitch in the 50's. I'm hoping to gain some insight into it as I am thinking now that it is either a brilliant piece, or maybe there was a good reason no one else was interested in buying it. It is a 20 gauge and the ad for it stated 3" chambers. And it has 20 gauge chambers, -but the bores are 16 gauge! Its proof is 16, 3 1/4 tons, 2 3/4". The chambers are indeed 3", in fact they are actually 28" as the 16 gauge bore size is so close to the 20 gauge chamber size that a 20 gauge chamber checker slides in all the way to the chokes. There are no inserts in the chambers that I can detect. It seems clearly to have been built this way, although I can find no other shotgun in this configuration on the entire internet. I have not shot it yet. I thought it would be a nifty little grouse gun. It is just 6 pounds and points beautifully for me. It looks hardly used. Single trigger.
My questions would be, why was this built? Are there others? My guess is it was made for the American market and 20 gauge was more popular than 16 so they chambered the gun so that future owners could buy shells at Walmart?
Could there be any advantage in such an overbored gun besides that? Any disadvantages?
And finally, what loads would be appropriate?
I'm hoping someone finds these questions interesting enough to give their insights.

Can we have photos of the proof marks please?

I have seen references to 16 bores being chamber sleeved to 20 bore to make them more attractive in the American market.

Apparently they pattern and shoot perfectly well despite the oversized bores.

You may have bought one of those.

[img]https://photobucket.com/u/michaello...5/p/46666394-3dd6-4bd7-8f7c-a192473a0209[/img]

A 16 ga shell won’t go in the chamber??? The barrel flats indicate it’s a 16 b with 2 3/4” chambers.

The proofs say 16ga 2&3/4" chambers. The number inside the diamond is the chamber gauge. The bores are 16 ga too.

If a 16 gauge shell will not fit, then have you considered that you may have purchased a chamber sleeved gun to a 20 bore and it was not re-proofed? Removed the extractors and see if you see signs of a sleeved chamber.

Thank you for the photograph. It was built and proved as a 16 bore.

The date stamp (KXB) is for 1959.

It has clearly been chamber sleeved. If that had been done in the UK it should have gone back to the Proof House for re-proof.

See page 156 of Diggory Hadoke’s book “Hammer Guns” for a photo of the Proof Marks on a 16 bore chamber sleeved to 20 showing the 16 bore dimensions but the 20 (in a diamond) chamber marking.

At pages 156 to 158 he discusses the process, and remarks that “counter intuitively” it seems to work better than might be expected.

You might find yours works well, but you need to consider how much you have invested and the problems you could encounter on trying to re-sell it. I see it was described to you as a 2 3/4” 20 bore. Did you buy it from a dealer, at auction or privately?

Any chance Briley chamber sleeved it? Did they mark their handywork?

Ah. I will have to read up on chamber sleeving. What are the possible reasons one would choose to have a shotgun's chambers sleeved?

Proofed as a 16 gauge
Can you post a picture of the chamber end of the barrels?
Mike

The sixteen ga model 700's were the rarest of the 700 model guns. If you have one originally chambered for 20ga and it patterns well I think you may have a very good and super rare gun. I would not bother with a reproof since the gun in in America and the chamber sleeve was likely done here...Geo

I have had two, both hammer guns (my favs).
Still have one, works very well as a "overbored 20"
Fiber wads might be less effective, but with plastic wads there is no difference to my real 20ga.

For added info:
I did the sleeves on my two guns.
No material was taken out of the 16 chambers, so I have zero concern.

I chamber sleeved a 16 sterlingworth from 16 to 20. Two paper shells left in the chambers for 50 years had altered them to Swiss cheese. On a whim I put a couple 16/20 chamber adapters in it and shot a couple patterns. They were great. So I had the chambers reamed out and a set of custom made chamber adapters installed along with a reworked extractor for a 20 gauge. One of my kids still has it in his gun case. It worked well for pass shooting dove, Sporting Clays and crows of opportunity.

I had a smith chamber sleeve a 24ga to 28. My favorite quail gun.

On close inspection with a magnifier I can see that the chamber has been sleeved. There is no obvious seam but I can see a slight difference in the direction of the tooling marks between the outside of the barrel and a concentric ring on the inner side. The ejectors also have been reamed out and metal added so they are concentric with the rest of the chamber and there is a slight seam there.. It looks like a very professional job but it worries me that the gun is not in proof.

If you’re going to keep the gun you may rest assured that pressures will be well below those published for 20 gauge. We don’t have proof houses in the US so don’t worry about that.

On close inspection with a magnifier I can see that the chamber has been sleeved. Obviously, I now know, but I didn't know chamber sleeving could be done. There is no obvious seam but I can see a slight difference in the direction of the tooling marks between the outside of the barrel and a concentric ring on the inner side. The ejectors also have been milled out and metal added so they are even with the rest of the chamber and there is a slight seam there.. It looks like a very professional job but it worries me that the gun is not in proof.

Not in Proof by U.K. standards possibly but it has not had the strength compromised but I would in no way put 3" cartridges through it as the pressure would be an issue then. A 16 bore can be between .661 and .681 and still be marked as a 16 bore. The Bore is on the tighter side of the 16 bore barrel. I'd consider having it put back as a 16 bore and using it as such. Lagopus.....

Aside from possible pressure issues with 3” cartridges , as it weighs “just 6 pounds” you should regard a 1 ounce load as the maximum for recoil management and will find it more comfortable and possibly more effective with 3/4 and 7/8 ounce loads.

It may be worth patterning it with both plastic and fibre wads to see which it likes best.

Michael;

Your concern that the gun has not been re-proofed is prudent. If the gun was chamber sleeved by someone like Kirk Merrington, then one can assume with some reason that the chamber sleeve boring away of the original chamber was carried out in a workmanlike manner, and maybe it will stand up to pressures you submit the gun while firing it. If it was not Kirk or another of his caliber, then your worry continues as you cannot "see" how much of the barrel bore might have been cut away beyond the distance that it is safe to do.

What does the original seller to you say about this conundrum?

We do not have proof houses in the USA, and accordingly shotgun and rifle manufactures here use their own proof loads in their factory. I wish we had a USA proof house, but I suspect the lawyers do not.

With the last double rifle I built which had a service pressure of 38,000 psi I loaded heavy loads of 54,000 psi and shot two of these loads in each barrel (while I was behind a protective barrier). Even that does not make the rifle I built absolutely incapable of blowing the barrel, but it gave peace of mind somewhat.

So you have a chamber sleeved gun that you might decide to chamber sleeve back to 16. Why bother? The pressures of a 7/8 or 1 ounce 20 are not that much different than a 1 or 1 1/8 ounce 16. Chamber sleeving from 16 to 20 is far beyond most gunsmiths level of abilities. Poorly done they would take too much metal out of the old chamber to make fitting the sleeves easier. That leaves a gap which is soldered or welded, leaving a easily seen seam. It sounds like your was done in an expert fashion. There are half a dozen smiths in the US who could do that job. If you called them all the one who did it might even recall the job. Not a common job after all.

If the chambers were reamed out for the sleeves, then you will need to have it reamed out larger to fit a 16 gauge sleeve. Why remove more metal in the chamber area? Shoot it as is or send it down the road with what you now know. I’d love to have a overbored 20. To me that’s what that gun is. Proof means nothing in the US other than a vague endorsement of original configuration.