Reloads & "Pimple Bulges" in Barrels

[Kensal Rise]

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]

Very good to know.

[OH Osthaus]

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.

[Phil C]

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.

[Kensal Rise]

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

It sure isn't alien force fields...

[Big D]

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"?

[Phil C]

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.