My Parker 12 is actually an 11-gauge?
 

I was down at the shop last week to measure my most recent acquisition (mainly to confirm wall thicknesses in these old "twist" tubes) and to show it off just a bit to the owner (he's more of a British gun guy but he was actually quite interested, especially in the "fishtail" top lever as he'd never seen one before).

Everything was as expected until we measured the internal bore sizes of the gun. I've probably heard (or read about) this elsewhere (even here maybe?), but this 1887 Grade O hammer has a significant overbore for a 12-gauge gun, like 20k plus. The chambers are in spec for a 12 bore but the tubes are approaching 10-gauge in diameter. Even with that overbore, it still has lots of constriction (choke) left in both tubes. At 23k, this gun has been honed a fair bit (& the choke on the left tube is slightly less than what's in the right), but it's still fine (it has a minimum of 23 thousands width at it's thinnest point, about a foot from the muzzle) and all this "overbore" does (other than helping keep pressures down) is make it possibly pattern a little better.

Since I'm basically lazy (sigh!), instead of digging through the webpage archives I'd like to confirm my observations with the "cognoscenti" here. Is this a common discovery amongst the earlier Parker guns?

Older guns were often overbored, but over the course of many years, many things could have happened to your gun. All of my older guns are beyond the nominal (for a 12 gauge) bore size.

There are some Lifters that were chambered for brass (or metallic) shells of 12 gauge but the bores were 11 gauge.

Charlie Price, Richard Hoover and Austin Hogan began a list of those guns known to have been manufactures this way.





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The .023 wall thickness is not normal.

Back in the day, the Parker Bros. "overbore" was well known and companies that loaded shotgun cartridges used oversize wads in shotshells for them. This from the 1886-7 Chamberlin Cartridge Co. catalog --

Attachment 134987

I posted about being shown an 1890 Parker 12 gauge that had the barrels shortened by one inch a couple of weeks ago. My brass drop in gauge showed no choke in either barrel. several guys mentioned, as did Mr. Noreen here, of the over bore in guns of that vintage. Information provided me that the brass gauges would not give me a true reading of chokes form that era.

True that William, and to that statement I will add that a brass drop in gauge won’t give you a true reading of any shotgun choke. “True” choke readings can only be measured in thousandths of an inch.



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Mr. Murphy: You are correct.

As I mentioned earlier, this gun has been heavily honed (most-likely to clean-up "pitting" in the tubes). Less than 20-thou and I usually start to leave them alone (& that's dependant on where in the tubes the thin spots are, more towards the muzzles is much-less of an issue for me).

Chokes on this gun measure 0.033 and 0.029 "points" of constriction (from their nominal bore diameter) respectively, using a caliper-type of gauge.

The brass "drop-in" gauges are useful at gun shows for a quick assessment (& I have carried them there too) but proper gun shop tools are needed to assess the true nature of a set of doublegun tubes.

Only shops dealing in English doubles seem to be familiar with them.

The "honed" tubes combined with the No. 1 frame gets this circa-1887 gun closer to 7lbs (which is about my upland weight limit anyway, at least for the longer walks).

It's 93 outside here today, so in my mind this would be far easier to deal with...

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Very much looking forward to the approaching Fall.

That looks like a walk I'd like to take with a couple of good Setters!!

Not uncommon at all. Oversized bore. The chambering is what would actually determine the gauge.

I have an underlifter, made in 1874, and its bores are .75 (11 gauge) bhut the chambers are for 10 gauge shells. Spoke with Mr. Hoover, who wrote 2 very interesting articles about Parker 11 bore guns. He said some had 12 ga, some 11 ga, and some 10 ga chambers. I also have a DHE, made in 1889 that has 12 ga chambers, but overbored bores, to the tune of about .753 if my memory is correct. But it still measures mod & full with a bore gauge, so it may also have been an 11 bore gun. Seems best to expect the unexpected on some of these guns.

Can we sneak a 12 gauge shell into a chamber made for an 11?

A 12 ga shell would be very loose in an 11 ga chamber, but some of the 11 bore guns had 12 ga chambers.