Reloads & "Pimple Bulges" in Barrels

[John Campbell]

British gunsmith, Kirk Merrington, has made me aware of an increasing trend in his barrel repair work: "Pimple Bulges."

Apparently, these amount to a bunch of small bulges in the barrel, shaped like small skin pimples. Those who acquire them in their double guns are baffled as to the cause. And they almost always appear in the left barrel, along the bottom of the tube.

If you haven't already guessed, these are caused by shot pellets that escape from a weakly crimped cartridge, roll down the tube, and are then "ironed into" the steel when the cartridge they escaped from is fired.

The scenario goes like this:

A weakly crimped cartridge is placed in the left barrel.
Shooter fires the right barrel and recoil opens the crimp of the cartridge in the left barrel, allowing some shot to escape.
The shooter then fires the left barrel (as in clays doubles), and the remaining shot and wad iron the escaped pellets into the steel, creating "pimple bulges."
The shooter notices them sometime later...

This is an especially costly fix in O/U guns since ribs must be removed.

Moral of the story: Toss those soft-mouth hulls and save yourself some grief!

[charlie cleveland]

good to know...thanks charlie

[Mills Morrison]

Very good to know.

[Rick Losey]

thanks John - as more of us reload for the old pieces to save a little or due to availability of loads - the old adage "penny wise, pound foolish" needs to be remembered

[paul stafford jr]

excellent info , I haven't seen this problem before but with the high cost of shells it was only a matter of time till problems like this happen . I will check my shell crimps and cut open and recover shot and powder. throw out any weak hulls. the RST hulls are very thin pay close attention to them.

[Phillip Carr]

I recently looked at set of Model 21 12 gauge barrels as described. I gave Kirks information to the dealer that had the gun, and I believe Kirk may have these barrels currently. I wish I would have taken pictures. there was about 6 or 7 little pimples in the left barrel starting about midway down the barrel. Kirk felt he could remove these very easily I am anxious to see the barrels when they return.

[Paul Harm]

Not to discredit anyone,but I have trouble believing lead shot is going to cause " pimple " bulges in a steel barrel. Just my take on it.

[John Campbell]

Paul:
No discredit to your post, or take... but what would you suppose does create them?

It sure isn't alien force fields...

[John Dallas]

I'm sure Mr. Merrington has forgotten more about barrels than I'll ever know, but soft lead seated in the outside of a soft plastic shot cup causing dents in steel? I think not. If there was to be some distortion, wouldn't it show as a groove rather than a "pimple"?

[Phillip Carr]

The barrels I examined looked like the dents I used to see when I was a kid shooting tin cans. If you ever shot a tin can and then looked inside you know what that looks like. The little pimples looked exactly like that except were a little smaller. Dents were along the bottom of the left barrels and ranged over about a 12 " length. from about 1/2" to 2" apart. Some were more shallow than others. I had originally thought it might have been droplet's of water that had frozen in the barrel prior to firing. I spoke with the gunsmith after he spoke to Kirk, he told me that Kirk described to him exactly what the barrels looked like as if he had a picture in front of him. He told the Smith that he has seen this a number of times in his career. I would also have doubts, but I examined the barrels myself. I bet if you would have rolled a number 2 or 4 shot down the barrel and they would have laid in the small pimple area.

[charlie cleveland]

i mite could see this being the problem with a large size shot such as a no2 or a bb size shoy in lead...but could be possible the reloader was useing steel shot..just my opinion ... charlie

[Pete Lester]

An increasing trend? The old timers didn't stretch their hulls as far as they could and then some, especially in the Depression? I am certainly no expert but if it's an increasing trend perhaps it's related to something relatively new like harder than lead shot??? Maybe there is a history of this phenomenon but this is the first I have heard of it.

[Phillip Carr]

The barrels I looked at were damaged back in the 70's so not steel. I had understood this was more of a common problem years ago. With all of the years of combined experience I am surprised someone has not seen this before.

[John Farrell]

This conversation supports roll crimping shells for use in older double guns. Roll crimping was the standard when most of the old guns were made, so . . .

Or the basis of a new conspiracy theory has been created.

[Paul Harm]

My theory is that back in the day if you missed to many birds the aliens would punish the hunter by messing with the barrel. If you were really a bad shot they'd let you load the new smoke less powder with your old Black Powder measure and blow up the barrel. And by golly that's what I believe - now someone prove I'm wrong.

[Dennis V. Nix]

I have never seen the type of barrel damage described so will just have to imagine what it might look like. I am wondering though how it could happen unless the shooter was extremely unlucky. If the shooter was shooting at flying targets and the gun was pointed up after the first barrel was shot the gun would probably still be in the up position making it unlikely the shot would roll down the barrel. If the shooter was firing at a ground target such as a rabbit then the barrels would be pointed down and one would think the shot would have started rolling down the barrel as was described in the opening paragraph of this thread. How unlikely would it have to be that the unlucky shooter would ALWAYS shoot the second barrel as the indicated shot pellet would be in the same position of the barrel? I have no idea what is causing the damage but for it to always be in the same place if you accept the open crimp theory seems unlikely to me.

For those who will check their shotshells and pull the loads, why not simply fire them in the right barrel? Seems like a lot less work.

Forgive me if I am missing somethiing here.

Dennis

[Paul Harm]

Maybe some poor soul didn't have the money for shot and was using gravel ?

[John Farrell]

No matter how the gun would be held, the "loose shot lying in the barrel" would end up either on the ground or in the receiver. I think it's physically impossible to get a second shell into the chamber, either by mechanical action or hand feeding a new shell in and not have the barrel pointing up or down. Sounds to me like a crop of hogwash is floating around in the universe, again. Probably started by someone located near Area 51.

[Eldon Goddard]

Area 51 is real, try getting close without getting arrested. Both my grandpas worked at "The Base". One unloaded A bomb parts from a B52. The other built the houses, pig pens, buildings, etc. That they would blow up. Who knows what was actually at area 51, but I doubt there is anything there now. Although they still conduct critical mass tests underground.

[Phillip Carr]

I think Mr Merrington would be qualified to judge what causes such small bulges. Since I was able to examine a set of 21 barrels currently with him for repair I can testify I have seen the UFO :). Possible I could get some pictures. My understanding as to how this can happen is as follows. In fact I was shooting quail today over my dogs with my sxs. I shot the right barrel followed by shooting the left barrel only a few hundred's of a second apart. When hunting I have done this many times. I have never experienced an issue doing this. I am guessing that many of us do this regularly. I am not under the impression that pimple bulges are an epidemic but that it can happen.The theory is that upon firing the right barrel the shotgun recoils. The shotgun is stopped from recoiling as far as it would if your shoulder did not stop. This reaction forces some of the shot which may not be properly restrained (the crimp) to be thrust down the left barrel out of the loose crimped shell at a much slower speed then the pellets that are soon to follow at about 1100 fps., when the left barrel is fired. I think that whether the barrels are pointed down, up, or level this could still be an issue. Some pellets may in fact clear the muzzle, some just may not.

[will evans]

I understand the concept of a pellet coming loose in the other barrel, and then being pushed against the barrel walls by the rest of the shot and gases after the trigger is pulled. What I don't understand is how in blazes a piece of lead, under any amount of pressure, results in a deformed piece of steel. Is the lead pellet somehow instantly hardened by the process, resulting in the anomaly of lead being able to compress steel? If anything, shouldn't the process result in a tiny lead pancake?

[John Dallas]

If that theory is valid, then after only firing one shell, pellets could be rolling out of the barrel. I've never witnessd that, and I load my AA's until they split

[wayne goerres]

If I had a piece of soft steel to try this with I would do it right now. Take a piece of mild steel (1/16") and lay a piece or two of chilled shot on it and give it a good wack with a hammer and see what happens. Might make an interesting experinent. Just a sugestion.

[Phillip Carr]

This is off Merrington's web site. I would think a Barrel Smith with such qualifications might have seen a lot of damage in his training and career, and might be qualified to examine and determine the cause of damage to a barrel. Since I know of no other reason that would cause the damage I am excepting the shot theory.


Kirk started his career as a barrel filer at Churchill Ltd., in Birmingham, UK. After financial ills forced that famous company to fail and be sold, Kirk immigrated to the United States where he spent many years at Buckhorn in Dallas, TX – then set up the gunsmithing shop of Briley Barrels with Briley Manufacturing, in Houston, Texas. There, he became a renowned barrelmaker and multi-talented gunsmith, specializing in classic English double guns.

[Richard Flanders]

This is a mysterious and very interesting issue. I sure can't see how a lead pellet could deform a barrel wall but I guess something did it and what else could it be?

As for Area 51. I took off out of Vegas once and was headed somewhere that was on the other side of Area 51. I was cruising along at about 10ft off the desert and at 5miles out of Vegas the tower comes on with "Ahhh, little red plane headed NW out of Vegas, do you realize where you're headed?"..... of course I answered, "Ahhh, no, where??"...:whistle:... all the while wondering how the hell they could see me from 5 miles away! I turned around and diverted before the F-16's arrived....

[Phillip Carr]

I agree Richard it is hard to understand how a lead pellet could do this. Then again, I wonder how big of a piece of a fiber wad would it take to bulge a barrel? They say snow in a barrel will bulge a barrel, ( Here in AZ we have never seen snow, I hear its fluffy white stuff) LOL. Just rubbing it in, it was 81 F yesterday when I was out hunting.
I know that high speed projectiles when they strike a stationary object, even when it is soft can react quit unusual. I believe I recall seeing pictures of straw driven into a telephone pole during a tornado.

[Rick Losey]

I agree Richard it is hard to understand how a lead pellet could do this. Then again, I wonder how big of a piece of a fiber wad would it take to bulge a barrel? They say snow in a barrel will bulge a barrel, ( Here in AZ we have never seen snow, I hear its fluffy white stuff) LOL. Just rubbing it in, it was 81 F yesterday when I was out hunting.
I know that high speed projectiles when they strike a stationary object, even when it is soft can react quit unusual. I believe I recall seeing pictures of straw driven into a telephone pole during a tornado.

the only barrel damage I have non-anecdotal knowledge of was a Stevens hammer gun with snow in the fluid steel barrels. The shooter had gone muzzle first thru snow covered brush. He knew he had snow on the end of the gun but did not look inside. The fired tube had a single split for a short distance at the muzzle.

i would think that an escaped lead pellet would either roll out the muzzle or be resting on the crimp of the shell where it would either be pushed out with the rest of the load or flattened in the forcing cone. How would it be suspended half way down the barrel to be an impediment to the accelerating shot column?

just wondering

[Richard Flanders]

How about loads where the shot load is a hair above the end of the shotcup to begin with. It goes off and gets shoved down the barrel and at some point for whatever reason it gets under the advancing front edge of the cup and gets 'run over' by the wad and forced into the barrel???

[Dave Noreen]

One of my close friends had a row of pimples down the bottom of the bottom barrel of his Diana Grade Superposed Lightning Trap Gun. Happened while shooting singles. Sent the gun to Browning, they sent it to FN, and three years later it came back with new barrels?!? Never heard an explination.

[Pete Lester]

One of my close friends had a row of pimples down the bottom of the bottom barrel of his Diana Grade Superposed Lightning Trap Gun. Happened while shooting singles. Sent the gun to Browning, they sent it to FN, and three years later it came back with new barrels?!? Never heard an explination.

When shooting singles one is supposed to have only one shell in the gun. Was that the case with your friend? If so the theory of recoil from the first shot dislodging pellets in the second barrel and being run over by the shot charge would not have been the case.

[Dean Romig]

Generally when shooting singles with an O/U only the bottom barrel is used for reasons of lower felt recoil.

[Destry L. Hoffard]

Maybe I'm wrong, but isn't this what's always been called riveling?

Destry

[Phillip Carr]

Destroy I looked up reveling on Google and found a few articles. It sounds like it could be the same thing.

[John Campbell]

Destroy I looked up reveling on Google and found a few articles. It sounds like it could be the same thing.

Sorry to say, but it is not. The original scenario is the functional story. There will always be other "expert opinions," but these pimple bulges are what they are: Real.

But there is little need to concern yourself with them as long as your cartridges are securely crimped.