Barrel wall thickness

[OLD GEEZER]

Jay: I thank you for a very informative response to my question. I for one wish you would chime in more often. I have learned alot in the time that I have been a PGCA member and having your knowledge is very helpful.Thanks Thomas L. Benson Sr.

[Dean Romig]

Originally Posted by jay shachter

Hello Guys,

Unless you are shooting guns with obstructions in the barrels, there is no measurable risk shooting reasonable loads in guns with 20 thou wall thickness at least 15" from the muzzle, provided all other issues are sound, like tight ribs, no serious dents, etc. This is not opinion, but data collected for decades under controlled testing.

From the muzzle Jay or did you mean from the breech?

Thanks for the very knowledgable post. Information like yours is very valuable for everyone who shoots these old doubles.

Was the curve you are referring to printed in Parker Pages or on the forum here someplace?

Dean

[Drew Hause]

This? By DuPont in the mid-30s

[Bill Murphy]

I believe that Sherman Bell may have done the "inch by inch" pressure graph for black and smokeless loads. I don't know which one of his articles may have included this information.

[charlie cleveland]

looks like all the powder loads were fairly close in peak preasure.... charlie

[Joe Wood]

Jay, thanks a lot for your input--you clearly stated what I'd feebly tried to say earlier in this thread.

I always carry a wall thickness gauge with me and it has saved my butt several times. One very nice gun offered by a well known dealer and having no visible defects gauged .010! That was a close call! I too am amazed how few dealers have gauges capable of measuring the whole length of the barrel. Do they prefer not to know? Caveat emptor!

[J. A. EARLY]

"This is almost always in a 3-4" area very close to the top rib or bottom rib, and only on one side of the tube. As one person on this thread mentioned, virtually all vintage American doubles have a very noticeable lack of concentricity, ie thicker on one side than the other. There is also the matter of soldering on the ribs, with the required filing of overflow solder tight in to the rib, creating these thin spots."

Jay,

Thanks for the above reply. On almost every set of barrels, this is where I do find the thinnest spots. I had never understood why as one would think this area would not have been the one to meet the file as much as the outermost metal. The tendency is to measure the outside three-fourths of the barrel away from the ribs for thickness and to ignore the one remaining fourth of the barrels for measurement next to the ribs. Now I know why that is where they are the thinnest there. I see it on top more than on the bottom, with lots of low .020 measurements on smaller framed guns.

[Drew Hause]

Possibly 'splaining this. No infro on the load

[John D.]

Originally Posted by jay shachter

Hello Guys,

I don't chime in on these conversations often,...Sorry for the long post. It is my reason for not writing. I can't say things in a few words while typing!

Jay, I really wish you WOULD chime in more often - excellent post - thank you..!

As a few of you know - I've been following this thread closely for a while, but more recently - hanging on every word for personal reasons. You see...

Recently I put up my DH 20 DAM Parker Show gun for sale (click here if you are a PGCA Member) and the potential buyer asked me what the barrel wall thickness was? I told him, honestly - I'd never had it checked - and after firing hundreds of RST and my own low pressure rounds through it - never thought to? So, Monday - I did..

To Jay's point about light barrels small bores that left the factory that way, I would agree. Well said! You see, this 26" DAM had an UNSTRUCK weight of 3 pounds exactly (no ounces stamped). Today - after striking and whoever refinished them - they weigh in at exactly 2 lbs - 8.2 ozs, a difference of only 3.8 ozs..

Now - on to the other measurements - bore size (L) is .618 and .619 (R) with constrictions of 0.16 (L) and 0.11 (R). The barrel wall thickness is 0.019 (L) and 0.015 (R) - BUT those are 7.75" from the MUZZLE, not the BREECH..??

So, anyway - I'm wrestling a bit with what to do with this little DH beauty based both on this thread and the collective wisdom posted in this thread regarding wall thickness... Leave it, TIG sleeve, shoot it with removable 28GA tubes - leave the original BBLS as is, etc...???

Hope this helps with the data from my little DH bbls..

John

[Smoothebore]

Sorry to tell you, John, but there are 12 inches in a foot, but 16 ounces in a pound. Your difference is 7.8 ounces.

Dave