Barrel Wall Thickness

[Bill Murphy]

That would be the easy way.

[Tom Brown]

Would anyone know what the wall thickness would or should be at the muzzle for say imp. cyl, mod, imp. mod, full on a 0 frame 20 gauge Parker? Thanks in advance. T.

[Austin W Hogan]

Adding the numbers on Dr Drew and Robin's sketches give a breech width of 1.205 inches. Two 1.205 diameter barrels would be 2.410 inches; a two frame is 2.375 across the standing breech and most Parker barrels look like sewer pipe when compared to an English gun.

Best, Austin

[Dean Romig]

Originally Posted by Austin W Hogan

and the chamber wall thickness of most Parker barrels look like sewer pipe when compared to an English gun.

Best, Austin

Sorry Austin - I thought your statement needed a little editing

[Austin W Hogan]

I just took the micrometer to the chamber wall of a 1 1/2 frame DH which is a little under 7 pounds. It measured .190 inches. There must be a lot of lightening holes in those 6 and 6 1/2 pound English twelves if they have a .287 thickness. I think the diagram is in error; adding .080 for the difference in bore diameter and chamber diameter makes it a little closer, but not quite as thick.
A three frame ten is .245 at the breech.

Best, Austin

Added; Bill is correct, a flat or dovetail is cut to join the barrels at the breech removing about 1/8 inch from the breech width.
I just measured a three frame 12 ga barrel. The chamber wall is .265 inch thick. The barrels are stamped 5 12

[Bill Murphy]

Austin is right and the diagram is wrong, at least for a breechloader. No English bird gun has .238 chamber walls. A second thing to consider is that the barrel wall thickness at the chamber is not doubled at the inside in most double guns. Austin's .190 chamber wall dimension is way less than .380 between the chambers of a 1 1/2 frame Parker. The one I just measured is only about .308.

[Tom Brown]

Just to clarify things, what should the thickness of the choke wall be for imp. cyl, mod, imp. mod, or full on a 0 frame 20 gauge Parker? I measured the thickness of my choke walls except would like to know what other choke wall thicknesses measure. Thanks in advance. T.

[Austin W Hogan]

The thickness of the barrel depends primarily on the frame size with respect to gauge, and secondarily on length. The barrels were finished by longitudinal hand filing to fit a general set of outside diameter checks. The filing was generally done to balance the gun at the hinge, but it could be muzzle heavy or light if the customer ordered. The longitudinal hand filing produced barrels that were not necessarily concentric with the bore, and wall thickness can vary side to side or top to bottom. There is no standard thickness.
Some guns appear to have thick barrels because full choke barrel muzzles are .040 or more thicker than the bore.

Best, Austin

[Jean-Paul Lavalleye]

Following up on Drew Hause's above post regarding The Hunter's Encyclopedia from the German proof house, is there data of actual measurements, current or old, of Parker barrels minimal wall thickness at end of chamber, regardless of length, for 12, 16, 20 & 28 gauge guns?

I currently own three Parkers on which I've made this measurement using Hosford and Co. barrel wall thickness gauge. The chamber minimum wall thickness data for these is as follows:

1.) BH 12b. on a no. 1 frame, R ≥ 0.088, L ≥ 0.094 (Damascus barrels)
2.) GH 20b. on an 0 fame, R ≥ 0.100, L ≥ 0.092 (Damascus barrels)
3.) DHE 28b. on an 0 frame, R ≥ 0.084, L ≥ 0.076 (Titanic steel barrels).

All of these have been shot for many many years (not by me) and measure up well in terms of min wall thickness and bore diameters. Kirk Merrington tells me that, in his experience, Parkers and other American guns tend to have wall thickness at end of chamber that are considerably less than found on English or German guns (in the 0.080"-ish range). Yet this does not seem to be problematic. The Sherman Bell articles of a few years, in the Double Gun J., regarding the strength of Damascus barrels would seem to support this conclusion.

Is there data somewhere that would show how low you can safely go with these thicknesses (or how low Parker went when they were making these guns)? I am currently looking at a 16b. Parker on an 0 frame where that minimum thickness (for a 2.5" chamber) is 0.068" on one chamber and 0.071" on the other, with all other measurement being fine; bores at 0.667, min barrel wall thickness at 0.030." This gun has very obviously been shot quite a lot. Is it safe?

[Double Lab]

JP,
I looked at that 16b you are referring to on Sat. and without any way of measuring other than by my eye they looked just fine to me. Your measurements of the BWT seem to me to be quite acceptable and the bore diameter is well within specs. I would have no problems shooting it with low pressure handloads or RST loads. Have the barrels been blued? I did'nt examine them that closely but that is a sweet gun. I was really interested in the smallbore P grade with twist barrels.

Daryl