Signs of Altered Bores and Chokes

Foxhound · Post by **Foxhound** » Wed Feb 11, 2009 5:16 pm

Are there any visible signs to look for to determine if a shotgun bore and/or choke has been altered? Were early Fox 12 gauge bores standardized at .729?

Researcher · Post by **Researcher** » Wed Feb 11, 2009 7:21 pm

Generally the early Fox doubles seem to run a bit on the tight side. I have them from .722" to .727".

FRBRIT · Post by **FRBRIT** » Thu Feb 12, 2009 6:50 pm

Good question! I'm rather surprised at the lack of responses, I recently asked a barrel question myself and the thread went flat after just a few responses.

I'm starting to wonder if we as a group knows much about Fox barrels and their boring. If guys do know they either aren't looking at the site or just not sharing at this time.

Here's what I've been lead to believe. The first thing to look at on a Fox to tell if it's original or altered is the choke tapers. The original tapers should be some where between 3" to 4" long with no parallel section in them. If they have a parallel section more than likely they have been opened up with a reamer and are not factory. The length of the tapers helps determine if the barrels have been cut I.E. if 30" barrels were cut to 28" they would have tapers about 2" long the same holds true for 28" cut to 26", the big kicker is if 30" were cut to 26" there may be little if any choke left.

The next thing would be chamber length. Researcher has some great information on what original chamber lengths should be and maybe he'll weigh in on them. The forcing cones are rather steep and typical of the era and vintage of the gun. Once you look at a few you should be able to tell if they have been lengthend and altered.

The barrels came in four different weights and were stamped just ahead of the flats with a numeral 1,2,3,4 etc. with one being the heaviest and four being the lightest weight, but don't take this to the bank. I've looked and several Foxes the numbers were missing on and I've assumed they were struck of while striking the barrels.

Well that's about what I know. Hopefully other will help fill in the blanks.

DoubleGun · Post by **DoubleGun** » Thu Feb 12, 2009 8:36 pm

Foxhound,
I'm usually more interested in the condition and safety of the barrels than in their originality. If chokes have been altered you can usually see the reamer marks looking in from the muzzle end. If the chokes are what I want, or tighter, I can make them anything I want. The only time honing barrels bothers me is when enough metal has been removed to thin the barrel walls. Less than .020" barrel walls means the barrels will dent easily and be more vulnerable to high pressure from either an obstruction or high pressure shells. Normally barrels are thinnest about 8-9" from the muzzle, where pressure is quite low. The wall thickness that gets my attention is at the other end. There are a lot of Foxes out there that have had the chambers lengthened. If the barrels are #4's, the lightest ones, this can leave the barrel walls at the end of the chamber thin, less than .100". This is right where pressure is highest in the barrel and also where your arm and wrist are when you are shooting the gun. A failure here leaves scars. The first thing I check on a classic shotgun is if the chambers have been stretched. If they have, more investigation is required to make sure enough metal has been left. A bore gauge, a wall gauge and chamber length gauge really are a must when dealing with doubles from the classic era.
Cheers, DoubleGun

Foxhound · Post by **Foxhound** » Fri Feb 13, 2009 8:39 am

Thanks for the information. My early A-grade was sent to the gunsmith before the letter from Mr. Callahan was received. Gunsmith measured chokes at .000 and .012. The factory letter states Imp. Cyl. and Mod. Spoke with the gunsmith about measuring again and looking for signs of bore and choke work. The information you have detailed here will help me when I speak to him again.

Twice Barrel · Post by **Twice Barrel** » Fri Feb 13, 2009 11:55 am

Before concluding that the barrels have been "opened up" a trip the the pattern board is probably in order to verify your chokes are not in fact shooting Improved Cylinder and Modified patterns.

Foxhound · Post by **Foxhound** » Tue Feb 17, 2009 10:34 am

Did the Fox factory pattern their guns to determine choke or did they go by a numerical measurment?

Silvers · Post by **Silvers** » Wed Feb 18, 2009 9:57 pm

I measured a set of Krupp 32" barrels today with .720" & .721" bores. Precison Galazan bore gauge was used. They're on a second gen A grade, record card isn't dated but ~ 1916 manufacture. Tightest and most uniform 12 gauge Fox bores I ever measured. Silvers

FOXIST · Post by **FOXIST** » Thu Feb 19, 2009 9:28 am

Foxhound I dont have alot of data but from several guns I do own I find like others have said that earlier guns seem to have tighter bores. I have 2 guns prior to 1910 and have measured several others and the bores run in the .724- .729 range. The chokes on these early guns also seem to run between 3 3/4" and 4 1/4" inches in long with a full taper(no parallel section).
Most of my guns from 1910-1929 have bores in the .726-.729 range with a couple exceptions in the .731 area but they may have been honed. Chokes in this period are 3 1/4- 4" in general with same full taper. I have one 1922 vintage gun that has .724 bores and 5"+ choke cones that come to .006/.024 or IC/MOD as in the factory letter.

The 5 later vintage 12 bores I own are all mid 30's guns and they have .727-.733 bores but some guns could be honed. these guns have at least 3" of tapered choke.

Silvers that is the tightest bore I have heard of in a FOX! Is that the gun that was ordered for "work at the traps".

Keep in mind that these are just personal observations and these should not be taken as any sort of standard of Fox bore measurements. IMHO as we gather more information thru this BBS we may be able to come up with some basic ideas of how Fox bores should blueprint thru the various periods of manufacture. Paul