Bore/Chamber Questions
 

A friend who sells quite a few guns has this issue:

Gun is SN 55,337 , an 1888 GH, 2 frame 30" dam, gun wt 8.5lbs, barrel wt 4lbs 7oz, stamped 4lbs 15oz. Wall thickness .035. Chambers .820, bores .753, .020 chokes both barrels. Bores are decent, a little pitting.

Question he asks, is this an 11ga or is it a hogged out 12 ga? Too small for a 10. A 12ga shell is sloppy in the chambers, a 10 won't fit. We are both leaning toward a hogged out gun. Any different thoughts? If it has been reamed, the original wall thickness had to be huge.

I believe that bore on a 11ga is .751, so sounds right for an 11ga.
http://www.tbullock.com/bpsg.html. Whether Parker made any 11ga, I have no idea.

Sure, they made them....in the hammer years, but this is hammerless, and that's the issue. And there are many way bored out to clean out pits so bore diameter is not the best or only indicator. Mike Jensen and I are both questioning this one.

Sounds like a reamed out 12. It is my understanding that the 11 gauge guns were in the very early serial numbers. I believe the # and year are to late for it to be a true 11 bore gun.

My grade two top lever 12 has .750 bores as well. It was clearly reamed to remove some pitting. But fortunately they left the chambers alone. Minimum wall thickness now is 49 thousandths.

.750 original bores in 12 gauge are not uncommon pre 1894.

True, but what about the chambers Bill?

Hello everyone. I'm new to the site (along with being a new Parker owner), but I think my gun may be relevent to this thread as well. I recently purchased a G grade hammer gun, 12 gauge, #1 frame, 45,XXX serial number. I measured the bores and came up with .752 in front of the chambers, and .749 behind the chokes. Minimum wall thickness is .040.

The best I can tell from the examination of the bores is that it doesn't appear to have been reamed out, but most likely polished recently. I'm loading Magtech brass, with 11 gauge wads, so I wasn't too concerned about the larger bore dia. It patterns well with a 3 dram, 1 1/8 oz. load.

Particularly in the pre 1890 guns, people shot black powder and cleaning was haphazard so moisture combined with the black powder residue and created sulfuric acid which corroded barrels. So its common that early guns have been reamed. Then also Parker commonly overbored new barrels, predating the overbore rage of several years ago. As Murphy said, lots of 12's were originally bored at .750. That is about 11ga size, so then is it an 11 or a 12, and the chamber size tells that, but sometimes a gunsmith would bore out a corroded chamber and you get a sloppy fit for a 12 with the delight of blow back upon firing.

There are many notations in the order books for"Clean out barrels"

Parker Bore Diameters
 

This topic arises several times a year. I think the attached table was posted on the old forum, but I have annotated it with pertinent numbers. The table is based on measurement of bores and chokes of 58 Parker guns with s/n from 284 to 241000 plus. This was prepared after many discussions with Charlie Price and others; Charlie indicated in TPS that Parker boring changed at around s/n 70,000 in 1892. This frequency analysis verifies this; Parker choke boring changed again with the move to Ilion. This was covered in PP articles on the closing of "The Parker operation".

The barrels measurements in the table are from 12 gauge guns. Each was tested for 12ga chambering from being listed as such in "Serialization.." ; by chamber diameter of .810 +/- .005, or both in some instances. The bores were measured at several places with a Stan Baker gauge. The individual bore diameters at mid barrel (15 inches from breech and /or muzzle) are listed in .005 inch classes in the table. A pattern began to emerge as the data was tabulated; there are definite modes of the numbers of barrels found with respect to bore diameter. A mode is a (bore) size class where more items are found than in adjacent size classes.

There are no modes in the diameters of barrels bored prior to s/n 5000. Damascus and laminated barrels are not homogeneous and are very difficult to machine with uniformity; King's mastery of tooling minimized these difficulties. Prior to King's innovation, barrel boring was cut and try, and reaming and polishing continued until the barrels were smooth.

There are two distinct modes of diameter in barrels 5000 to 70000; one in the .735 - .740 inch class, and a dominant mode in the .750 - .755 inch class.

There is a single dominant mode in the .730 - .735 inch class in the barrels made following serial 70000. "Emery out barrels" is a frequent note in early Parker order books, as Dave indicates. Were barrels of larger that .730 diameter the result of cleaning out, we should expect to find many barrels, in the .740 - .750 diameter classes; that is .010 - .020 polished away. The measurements show a minimum mode here in both eras.

There are two conclusions one can draw from this tabulation; Parker made few 12 gauge guns prior to s/n 70000. The shooters loaded 11 ga loads in available 12 ca cases.
OR
Parker's tooling was based on American industry of the time which worked in increments of 1/64 inch. Barrel blanks were pilot drilled to 11/16 (44/64) (.6875) inch ID followed by a rough boring of 23/32 (.718) inch, leaving 6 inches behind the muzzle .6875 to accomodate finish choke boring. This was followed by a 47/64 inch reamer. Some barrels cleaned up with this first reaming and polished to the .735 - .740 range, acounting for this mode. Those that did not clean up were reamed 3/4 inch and polished out to make the .750 - .755 mode. The convincer about this is Parker's nut borer which scraped metal away in an ogee curve to allow barrels to be choked to deliver, independent of bore or choke diameter.

It is evident that Parker's boring changed after s/n 70000, as a clear and distinct mode at .730 -.735 appears, and the .750 mode is absent. This may have been a result of the revolution in steel making at that time; or to production of ten times as many shotgun barrels with the appearance of the W93/W97 that made specialized barrel tooling readily available.

I have absolutely no idea of the speeds, feeds, and cutter designs used to machine damascus. I have discussed this with master tooling engineers Dave Suponski and Larry Frey. I hope that enough material will be found to support some comprehensive coverage in Parker Pages.

Best, Austin