Help - Wall Thickness at the Muzzle ?

[Dave Miles]

What do you guys feel is safe minimum wall thickness at the muzzle?
I'm thinking .010" or .012" I know the thinner it is, the easier it will dent, but where do you draw the line. Some sound advice is needed please.

[Richard Flanders]

.010" is only 2x the thickness of a beer can. I have a VH12 that was opened by an unnamed gunsmith who left me with non concentric chokes with only .017" in the thinnest part and these muzzles dent if you hunt in a strong wind; I easily took a small dent out with a large round wooden pencil once. I think .010" is safe but will most certainly get dented regularly without extreme caution at all times. Needless to say, the unnamed gunsmith is off my list.

[Dean Romig]

The accepted minimum wall thickness is .025"

[Dave Miles]

Richard, I'm aware of your situation with the unnamed gunsmith, but didn't know for sure what the dimensions of your walls were.
If .017" isn't worth a tinkers damn, then I guess .010" or .012" won't be either.
.025" it shall be then. Thanks for the advice.

[Drew Hause]

From the German proof house: minimal wall thickness at end of chamber, regardless of length, for 12, 16 & 20 gauge guns should be 2.3mm (.0906") for 'ordinary good steel' or 2.1mm (.0827") if a 'Special Steel' was used. Minimal wall of .6mm (.0236") was recomended in the "forward third" of the barrel ie. what Dean said.

One of the Greeners progressively reamed the muzzles to the point that he could trim the ends with a penknife and the barrels did not rupture/split with standard loads. I wouldn't be standing next to the gun or shooter during the experiment however.

[Harry Collins]

I witnessed a thumb lever Purdey with paper thin muzzels unwind from a 2 1/2 Eley with #6 shot.

Harry

[Bill Murphy]

Drew, what do the Germans say about the middle third from the "front of the chambers" forward?

[Drew Hause]

That's all I have Bill, but here's what the Brits say

UK Working Standards recomended minimum wall thickness measured 18" from the breech from Double Gun Classics p. 56, Vol. 1, No. 4 Jan-Feb, 2006:
2 1/2" 12g- .028
2 3/4" 12g- .032
Re-proof recomended minimum- .024

[Bindlestiff]

Wow, maybe I'll shoot my old lifter with what I thought were thin barrels. I'll roll out an old tire and put the old A grade to a proof test. Wish me luck!

[jay shachter]

Hey Guys,

Regarding barrel wall thickness, I have measured literally thousands of them. If you are using 25 thou as your minimum, you will be retiring most of your 20ga. Parkers and "O" frame 16ga. Parkers, as well as many of your other fine lightweight doubles. Most light weight Parker 16's and 20's range between 20 and 25 thou as their minimum, usually 6-12"
back from the muzzle. I am talking factory original, unmolested, original blue and factory bore diameter barrels. I have measured a half dozen Parker ORIGINAL barrels that got down to 18 thou in the same areas, and they were not honed or reblued.

If you look at the Shooting Sportsman from last fall I believe, they had an article addressing concentricity in barrels. The article was mostly about Holland and Holland and their quest for perfection in barrel making. The first few paragraphs asks the question; how to quantify what constitutes a safe barrel when buying vintage guns? The stated industry standard as mentioned in that article is 20 thou, not 25. It is important to clarify that this measurement should be beyond the mid point of the barrel set.

In all the measuring I have done, there has never been an American made double that had barrels with concentric boring. They all are signifcantly thicker on one side of the barrel than the other. The thinnest point is usually found in about an area that would constitute 1/8 of the total circumference of the barrel and in a 8-10" longitudinal line. The rest of the barrels are substantially over the minimums.

Just an FYI