Just What Gauge is It?

[SOLANCO]

I have a Pedersoli SxS percussion double purchased from a member of the Forum. Very nice gun if a little over weight. The barrels are marked 12 gauge. The left barrel is threaded and has a choke tube in it. Not the right barrel.

Happened across my choke gauge in my tool box and got curious. Applied it to this gun.
According to the gauge the left barrel with the screw in choke is 12 ga modified. But the unthreaded, untubed right barrel is 10 ga modified?!?

Has anyone else ever put a choke gauge to their SxS ml shotgun and got surprising results?
My gauge is from Galazan and gives correct results on my unmentionables.

 

[Old Hawkeye]

The choke is what the constriction is from the actual bore diameter of THAT barrel. Modern guns barrels are made to more exacting standards, so a choke gauge can be informative. Muzzle loaders can be all over the map. A barrel stamped 20 gauge can actually be a 19 gauge. A barrel stamped 12 gauge can be an 11 or 13 gauge. So until you know for sure what the bore diameter is you can't know what the choke constriction is. In other words, it's the amount of constriction from the actual bore diameter that determines the choke, not just what the constriction measures by itself.

 

[SOLANCO]

The choke is what the constriction is from the actual bore diameter of THAT barrel. Modern guns barrels are made to more exacting standards, so a choke gauge can be informative. Muzzle loaders can be all over the map. A barrel stamped 20 gauge can actually be a 19 gauge. A barrel stamped 12 gauge can be an 11 or 13 gauge. So until you know for sure what the bore diameter is you can't know what the choke constriction is. In other words, it's the amount of constriction from the actual bore diameter that determines the choke, not just what the constriction measures by itself.

I understand that. What surprised me was finding a barrel marked 12 ga measuring 10 ga. I was unaware that standards were so lax in ML shotguns!

 

[Lorne Johnson]

Short answer is "Yes, that is surprising." I looked up the Galazan choke gauge, and it is (has to be) based on an assumption of what standard bores are, and what standard choke constrictions are. The trouble is that standards aren't that standard. The standard bore for 12 gauge is .729 inches, however, a lot of modern guns are over bored, or back bored (.740 to .745). Older European guns are usually tighter .725 or even .720. On the assumption that your Galazan choke gauge uses the generally accepted standards, 10 gauge cylinder would be .779 and modified would be .759, which is considerably larger than even a back bored 12 gauge. So something isn't right. I certainly don't claim to know what the actual situation is with your gun, but the .759 opening is probably close to the outside diameter of the choke tube. The Pedersolis with choke tubes sold by Cabelas had tubes in both barrels.

In defense of Galazan (a pretty respected company) I am confident that their bore gauge is a well made $40 item. To take actual bore diameter into account would require a more dynamic device, more in the range of $400 plus.

I used to have a post year 2000 12 gauge Pedersoli choked cylinder and modified, and as best I can remember the cylinder bore measured .735 inches. My 20 gauge bores measure .635 cylinder and .623 modified, and requires 19 gauge Circle Fly wads. I also have a 1970's Pedersoli 12 gauge (much lighter gun) cylinder in both barrels with bores of .710 and .709 according to my caliper. So there have been manufacturing decisions that have resulted in a considerable range of bore sizes over the years.

The introduction of steel shot has led some companies to alter their choke constrictions as well.

Best of luck with it!

 

[tenngun]

I understand that. What surprised me was finding a barrel marked 12 ga measuring 10 ga. I was unaware that standards were so lax in ML shotguns!

Gage is balls to the pound. A .72 is twelve ball to the pound, the Brown Bess today is mostly .75, eleven gage, but eleven is an unlucky number. Original bess could go to .77. But twelve is a lucky number, and the ball size could be though of as a dozen to a pound. But… to have quick loading the bess often shot a .69 fourteen to a pound, however this didn’t sit well with bean counters in government who supplied lead to the army at a dozen to a pound even though that wasn’t what was shot. So armories got a little extra lead that all too often was sold on the sly, the army version of the purser pound.
My smooth rifle is a twenty eight bore, but I shoot a .530 ball …. 32 to the pound in it.
Thirty two is a handy number as you get two shot-to an ounce. .54 was a common size but many were .55 or .53 in the old days
Dozen is a lucky or sacred number. And we see twelve bore, twenty four bore.58, forty eight bore .44 and ninety six bore .36 as common in the old days, but you don’t shoot a .44 ball in a .44 Colt
Yes it’s all very confusing

 

[tenngun]

Not to mention French pounds tgat were heavier then english pounds. So the French musket shot twenty ball to the French pound and tge trade guns shot twenty four ball…. While we call it a sixteen bore and twenty bore respectively And the ball sold for the trade gun was smaller yet, under what we would shoot today… umph

 

[Loyalist Dave]

According to the gauge the left barrel with the screw in choke is 12 ga modified. But the unthreaded, untubed right barrel is 10 ga modified?!?

Has anyone else ever put a choke gauge to their SxS ml shotgun and got surprising results?

Yes I have but the question on the unchoked barrel would be..., how deep did you measure?

It's a muzzle loader so it's not unknown that the last 1/8 or 1/4 of an inch, sometimes more, is enlarged for the ease of loading. So a .755 reading (10 gauge modified) at the edge or lip of the muzzle might be more like .729-.735 if you got inside at an inch... and maybe even deeper.
They expect the right barrel to be fired more than the left, and so you will be reloading it more, and thus some companies make it easier to load, or think they do.

There is an old-school method of choking shotguns if the company was making shotguns for the man who would only own one gun, compared to the companies or the models made for more specific applications where the buyer could afford different guns for different game, when the advent of fixed choking became common. One barrel was left cylinder bore, because it's also the barrel to be used when shooting round ball at deer, as well as shot pellets at running rabbits, and flying quail or pigeon or dove or woodcock, etc. The other barrel was choked modified for farther shots, often second shots, on birds and small game.

Even when both barrels are actually choked, for the one-gun-for-everything idea, the right barrel one often finds Wider than Improved cylinder, more like what we call today "skeet" choke, and the left barrel is often a tad Tighter than modified, more like what we call today Modified/Full. I'm sort of a SxS "nut" and I thought when I first saw this that the companies were really lax in tolerance control... nope... they meant to do that. The idea, which carried over into modern breech loading SxS shotguns, was that the shooter would have a better chance at all birds "up close", and a bit tighter pattern with the left barrel which made taking ducks (and squirrels high up in trees) a bit easier.

Much more expensive SxS guns, have the chokes much closer to "classic" dimensions, and the owners of those could have one cyl/cyl for big game, one mod/full or full/full for waterfowl, one imp cyl/mod for upland birds, and one imp cyl/Imp cyl or even skeet/skeet for Dove and quail and clay birds.

LD

 

[SOLANCO]

Yes I have but the question on the unchoked barrel would be..., how deep did you measure?

It's a muzzle loader so it's not unknown that the last 1/8 or 1/4 of an inch, sometimes more, is enlarged for the ease of loading. So a .755 reading (10 gauge modified) at the edge or lip of the muzzle might be more like .729-.735 if you got inside at an inch... and maybe even deeper.
They expect the right barrel to be fired more than the left, and so you will be reloading it more, and thus some companies make it easier to load, or think they do.

There is an old-school method of choking shotguns if the company was making shotguns for the man who would only own one gun, compared to the companies or the models made for more specific applications where the buyer could afford different guns for different game, when the advent of fixed choking became common. One barrel was left cylinder bore, because it's also the barrel to be used when shooting round ball at deer, as well as shot pellets at running rabbits, and flying quail or pigeon or dove or woodcock, etc. The other barrel was choked modified for farther shots, often second shots, on birds and small game.

Even when both barrels are actually choked, for the one-gun-for-everything idea, the right barrel one often finds Wider than Improved cylinder, more like what we call today "skeet" choke, and the left barrel is often a tad Tighter than modified, more like what we call today Modified/Full. I'm sort of a SxS "nut" and I thought when I first saw this that the companies were really lax in tolerance control... nope... they meant to do that. The idea, which carried over into modern breech loading SxS shotguns, was that the shooter would have a better chance at all birds "up close", and a bit tighter pattern with the left barrel which made taking ducks (and squirrels high up in trees) a bit easier.

Much more expensive SxS guns, have the chokes much closer to "classic" dimensions, and the owners of those could have one cyl/cyl for big game, one mod/full or full/full for waterfowl, one imp cyl/mod for upland birds, and one imp cyl/Imp cyl or even skeet/skeet for Dove and quail and clay birds.

LD

The barrel which measured 10 GA is not threaded for a choke tube. The full reading on the gauge was 10 GA Mod.

 

[Archer 756]

N/A

 

[Sparkitoff]

The choke is the constriction from the nominal bore diameter. Historically, the bore is measured 9-inches from the breach. The difference between that and the muzzle is the choke. .010 being around I/C, .25 around M ... and so on. Your nominal bore diameter could be stamped on the barrels in mm like 18.3, for example. Convert that to inches, then measure your muzzle constriction in inches and do the math to get the real choke constriction. I have several Pedersoli's. One says 20 gauge Mod/IM. It is a 19 gauge and IC/ Light Mod when you measure it and do the math. One 12 gauge indeed is a 12 gauge, but another is a 13 gauge.

 

[nhmoose]

What does the bore measure? That is what counts