doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Measure those barrels if you can.

The blowup pictures has been making me a little worried, squeamish if you want to call it that. Finger and possible wounds will do that to you if you let them. How safe is that new gun or even the old ones. I already shoot low pressure loads when ever I can. But is that enough? Are my barrels safe to shoot? Case in point.

I bought a used set of barrels last weekend to add to a 20 LC Smith I have been restocking. The barrels were so close in both serial number and near perfect fit it seemed like a natural thing to do was to fit the extra barrels to the LC Smith. They were supposed to be 28" full and full.

Before I fit them to the gun I decided to see how they measured up. And the numbers did not add up. The barrels are for a 20 ga.. The chokes were just too much for a 20 I thought. I expected .020 to .030. and had near .040. Well the chokes were that compared to five inches from the muzzle. Two inches they were more like .022-.025. And the bore had a odd taper to it, not a constant bore I expected to see. They looked clean no pitting present, too clean I thought.

The bores had been reamed, cleaned up in dealer jargon. The result was five inches from the muzzle the barrels walls were .016 and .012. Now that area is way past my fingers so no risk of my hand getting messed up. At the end of the fore arm they were a decent .025 or so. But the profile of the bore and the wall thickness confirms a very poor reaming in the past.

The thin area started about half way down the barrels. The only thing I can figure is that they used a un-piloted reamer to clean up the barrels and it wandered off bore or the pitting was deeper at the muzzle end. Either way the barrels were scrap.

So I started think about my options. Sleeving is out due to cost. I had a set of 20/28 and 20/.410 tubes and thought maybe they would fit the barrels. Turns out the chambers need to be altered and the chokes reduced to get the tubes to fit. So next week the barrels and tubes are going to be sent out to have them fit to one another. The barrels are also going to be stamped as carrier barrel use only. So my 20 Smith will be a fun gun to shoot skeet with the extra 28 and .410 tubes in the carrier barrel.

To think just a few years ago I would not have thought of or known how to measure a set of barrels. Now I do and even though the tools to do so are not cheap I will not shoot a old double without using them to check the barrels. So starting tomorrow I am going to start measuring every set of barrels I own. Any too thin will be pulled from the list of shooter. I probably have measured a third of my gun when I bought them but now understand the need for complete safety checks for all of them. For peace of mind I am going to measure them all. I suggest you do the same if you can.

good Idea Jon

it is a small investment when the risks are considered

I passed on what may have been a heck of a deal a few years back because the bores were too clean and I couldn't check them

so - I got the tools, fitted a case for them and they ride in my truck, about a year later a similar opportunity arose and and i was able to be sure of it - I figured the whole set paid for themselves then and the uses since have been a bonus

Great advice. A Parker D 12 at a recent auction here had barrels so thin at the muzzles you could have slit finger on the edges.Bores looked perfect and it looked like a very aggressive reaming job to get rid of some pitting.

Jon, that thread has had me thinking off and on all night since reading it 4 or 5 hours ago. I must say, I haven't had this much trepidation in my gut regarding my beautiful old guns since the days just before I bought my first Damascus barreled double 14 years ago.

And it doesn't seem to matter that, in most cases, the fears are unfounded and irrational. I've had an almost prophetic fear of losing fingers since I was a child, and don't think those spooky feelings were allayed any.

I think going through all my guns over the winter. much as you've suggested, would be a good way to become a little more intimate with them as I was when first acquiring them. It would be a good way to judge their integrity as well as take care of any little maintenance that is needed.

Thanks for posting.

I also check the wall thicknesses at the ends of the chambers where the forcing cones start.

In looking at many of the on-line sites, you see many where there are these older sxs that are listed as having "mirror bores", this brings up a red flag to me every time.
Of a few that I bought with these mirror bores, they were honed out.

There was an article on the Shooting Sportsman forum a while back that was very interesting about pressures and how much it dropped, here are what was posted and if anyone has any thing to add or dispute please do as it might help in determining what is true or not.

inches:pressure

3/4 : 10,000
1 1/2 : 5,000
3 : 2,500
6 : 1,250
12 : 675
24 : 338

This was in reference to Red Dot powder with a pressure of 10,000 psi.
If this is the case, it would seem any barrel failures past 3 inches would be caused by an obstruction.

I ordered the Manson gauge from Brownells the day after Drew Hause started his thread. It's probably not as precise as the $600 tool; however, size, ease of portability, and certainly cost were all considerations.

I have used a Manson type gage that I built, and after reading on this site about using it horizontal, it is very hard to get repetitive readings. It was found that if you hang it vertically, the weight now is not on the rod where the measurement is being taken.
From what I see on Brownell's site, you would have to add a spring opposite the needle on the rod side as there is no way to keep the ball bearing in contact with the barrel.

The only think I found that was wrong with this gage is that you need someone to write your reading down.
I have since built a Galazan type gage that is far easier to use, but even along with the Brownell one, you would have trouble using it at a show or such.

A bore and choke gauge will tell you a lot re excessive honing. If we're talking European guns and it's far enough out of spec to be out of proof, that's a red flag--unless it carries the proper reproof marks at the current bore diameter. Fairly easy to carry a bore and choke gauge with you as you walk around a gun show. Wall thickness gauge is a bit more problematic. But if the bore diameter throws up that red flag, you can always go retrieve the wall thickness gauge from your vehicle if you're still interested enough to check.

I posted this on the PGCA site some time ago.

1891 Grade 3 barrels matte blued but with a potentially stunning Damascus pattern showing through had been cut, had what looked to be moderate pitting, and on checking the bore dimensions was found to have an about 1" long bulge, 1" back from the muzzle on the right; but the bore gauge showed the bulge to be only .004" and the wall thickness was .024". It took some time, but I was able to get the brass stop of the Bill Henry wall thickness gauge into the bottom of the deepest pit, and it was only .002" with a wall thickness still .029".

1903 Grade 3 D4 barrels, also blued and couldn't see the pattern. I couldn't tell if they had been hot tank blued, but they had 4 weep holes drilled in the bottom rib. The chambers had been extended from 2 5/8" to slightly more than 2 3/4" and had been honed. The left chamber minimum wall thickness was .114 but the right only .100. They were 2 frame barrels, and despite bores of .736 (also suggesting previous honing) had wall thicknesses 9" from the breech of .045" and 9" from the muzzle of .030".

My point is that (almost) NO 100 year old barrel is now as it left Meriden, and without the proper tools it is impossible to adequately evaluate the barrels. AND it takes a long time to do it right. It is not easy to eye-ball the pit, rotate the barrels in the proper position, and try to get the brass stop in the bottom of the pit.