shotgun barrel dent removal at home with pictures.


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Dave Bulla
May 4, 2010, 03:42 PM
Hi all,

First time on the forum and my very first post. Looks like a real cool site. I thought I'd share a recent repair story with ya'll.

However, like all stories, a little background is probably in order. All my life, I've always wanted a quality SXS shotgun similar to the Fox Sterlingworth my dad has. I bought one once for $75 from a pawn shop with a broken stock and a dent in one barrel but it still had the typical Fox "vault door tight" yet "butter smooth" action. The plan was to make my own stock and have the gun reblued/repaired as needed. Lesson learned on that gun? Don't let a gunsmith who doesn't know old double guns work on one no matter how reputable, expensive, beautiful or customized of a rifle he builds. Old shotguns are a whole 'nuther ball game. This fella fixed the dent then threw the barrels in his hot blue tank where they and the ribs ended up laying in pieces after all the solder melted. But hey, he didn't charge me for his work...

Fast forward about 20 years.... I finally happened across another SXS that was in my price range. It's a German Guild gun with only the name Remo on the rib. Krupp barrels, a Suhl action (If I recall correctly. Not sure of the spelling either...) Anyway, with the European style cheekpiece and the stock spec's it fit me better than just about any other gun I've picked up and it was possibly even smoother and just as tight as Dad's Fox. Blueing showed wear and case colors were about gone but man what a gun! Chambers are the European 2 1/2" so ammo would be a little tricky I thought but then the guy in the Cabella's gun room said it should handle low brass 2 3/4" shells just fine. Said he had an old Fox with short chambers and had shot hundreds if not thousands of 2 3/4 shells through it. Cool!

Well.... went and shot the gun the day I bought it and loved it but then noticed the lever sticking, the action hard to open and once reclosed, it was a little loose all of a sudden and I'd only shot half a box. So... back to the store and they say they can fix the gun as that should never have happened. Months later I got it back and it looked like it had had the stock clamped in a vice, screws buggered and the bottom plate put back on crooked. There's more of my bad luck with gunsmiths and doubles... Took it back and showed it to the head honcho in the gun library and he was clearly disgusted and said he'd make it right. I wasn't sure if I wanted their guys working on it again and told him so. Told him I'd planed to eventually do a refinish and have something really nice to pass on to my kids. He came back with the question of "When did you plan to do that?" I wasn't sure but just said "someday". He then took out his card file and gave me a card to a gunsmith that he said worked on his personal guns. A guy who had worked in the Browning custom shop and specialized in double shotguns. He even went so far as to offer that they would pay half for a full restoration and I thought that was pretty fair.

Long story longer...

The gun came back absolutely beautiful. Everything had been redone except the wood. Screws retimed, case colors, barrel blue, back on face, hinge pin, etc etc. The gun was mechanically like brand new.

Back to the range again but with proper 2 1/2" shells and dang what fun! Even had me one of them fancy clay bird throwers that have three legs you shove in the ground, cock and pull a string to throw. Beat the heck out of my usual hold gun in left hand, throw with my right, drop thrower and shoot routine. About a box of shells into the fun, I'd developed a routine where I stood on two of the feet of the thrower to keep it from coming out of the ground, shoot a clay, break open the gun to pull the empties and then reach down, cock the thrower, load it, load the gun, pull the string, shoot and repeat.

Unfortunately for me, at one point when I had pulled my empties and was cocking the thrower, the catch didn't hold properly and just as I let go of the thrower arm, it decided to release and it came flying around and hit the right barrel of my gun which was opened and in my left hand! :twisted: :oops: :roll: @$%!#$!!!!!

Made me almost physically sick.

Here's a picture taken today before I started the repair.
http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair002.jpg

Over time, I got over it (sort of) but I always wanted to get it fixed. The day it happened, I called the gunsmith who had done the restoration thinking "this guy I trust to work on it" only to have him say "we don't fix dents".
"Why not????"
"Because NOBODY is ever happy with the results."
"Really?"
"Yup."

"Damn."

So there it sat for about two years. I eventually started shooting it again and had no problem but really wanted to fix it. Did a little reading and research and found the common method was to use a hydraulic mandrel that inserted into the bore and when in position pressure was applied to push the dent back out. However the tool was pretty expensive and I don't have extra cash laying around most of the time... But if you look in the pic above, you will see my solution. I'm a professional industrial mechanic by trade with an aviation background and know several machinists and have access to tools and materials.

Dang, just looked at the clock and saw it's time for me to head to work right now....

I'll continue this later.

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Dave Bulla
May 4, 2010, 03:43 PM
Okay! I'm back home and I'll try to pick up where I left off.

The tool you see in the picture is one I had made by my machinist friend from a piece of Sheffield steel round stock. I had to look up the nominal bore of a 16 gauge and if I recall correctly, it was .662". I talked to the machinist and he suggested I take a direct measurement instead of relying on supposedly correct specifications. He loaned me a tool I know only as a snap gauge. It's like a little T shaped thing where one side of the top of the T is spring loaded. You insert it into the bore and turn the handle counter clockwise to release the spring tension and it pops out and puts pressure against the sides of the bore. Once you feel it is properly centered, you turn the handle the other way and it locks the T in place then you pull it out and measure across the T with calipers or a micrometer. The bore on my shotgun actually measured .667 so it's a little oversize I guess. We decided to make the tool to the nominal .662 which would give 2 1/2 thousandths clearance all the way around it. He also used a piece of hex shaft and made a sort of ramrod that I could use to tap it into place.

Here is a picture of the mandrel and the shaft. The threads are 3/8" fine.
http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair015.jpg

If you look closely at the mandrel you may be able to see a line around it about in the center. That is to mark the boundary of the .662 diameter untapered portion. The stepped part leads to a shoulder. There is about 1/4" of taper after the shoulder and then it is parallel from there to the line. After the line it tapers like the ogive of a bullet.. The front end has a 5/16" hole bored into it so that if it got stuck, I could insert a piece of 5/16" cold rolled steel from the muzzle and use it to tap the mandrel back out the other way.

Here is a view from the front end.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair016.jpg

And here is the tool with both the threaded shaft and the 5/16" round stock piece. Notice also that on the hex shaft, there is a strong shoulder that is the primary bearing surface so as not to have to rely 100% on the threads.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair017.jpg

Dave Bulla
May 4, 2010, 03:45 PM
So, a simple fit test proved to me that the tool would slide down the bore with minimal binding and when it got to the first dent, it stopped. Just the fit I wanted.

Now, there is one more tool that I'll be using and that is a copper hammer. Copper or brass would both work but copper is softer by a good bit so that is my tool of choice.

Once the tool stopped at the first dent, I gently did a series of little woodpecker like taps on the side of the dent towards the fat part of the tool then pushed on the rod with my hand, tapped again etc. I repeated this several times then decided to use the hammer on the end of the hex shaft to give it some gentle taps. When it had moved about 1/2 inch I saw that most of the dent was gone. Cool! More tapping all around the dent and I could turn the tool with the shaft but it was still fairly firm. I pushed some more and felt the tool move down to the second dent and stop again. I repeated the process just as I did on the first dent and it too came most of the way out.

After removing the tool and giving the a barrels a wipe with a cleaning patch dampened with some Hoppes #9 here is what it looked like.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair005.jpg

Dave Bulla
May 4, 2010, 03:46 PM
So far so good eh?

Well, I figured I could get it better still. My original plan was to use some steel or brass shim stock to wrap the side of the mandrel opposite the dent and tighten it up and repeat. However, a lack of shim stock on hand and the advice of the machinist combined and I just used some scotch tape instead. One long piece that ran well into the tapered areas was tried.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair006.jpg

The fit was snug but still a slip fit and again, the tool stopped at the dents. I repeated the initial process until the tool would move by hand through the formerly dented area. I pulled it out and added a second piece of tape and repeated yet another time.

This time the fit was even more snug and I had to use the 5/16 cold rolled round stock from the muzzle to tap it back out of position. I should have turned the 5/16 stock down a little on the end to get a slip fit in the front of the tool but I didn't . It got a little stuck in the front and the tool and both shafts came out like this. Once it was out, I realized that it wasn't really stuck, just that the rod and hole fit together really snug like a steel ferrule on a fishing rod. They come apart with a nice little pop. Oh and by the way, there is my copper hammer.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair009.jpg

By now, I was pretty happy with the results. Here is a pic looking down the barrels with reflection on them trying to show if the dents are visible at all. I can't see them.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair010.jpg

Next was a trip outside to check things in natural sunlight. This one is still in the shade and it looks real good.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair011.jpg

Now here is the oddball pic. Once I got into natural sunlight, the spots showed up quite a bit.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair012.jpg

The only thing I can figure is that possibly the metal itself moving during the denting and the dent removal process may have done something to the blueing there. Sort of like if you painted a piece of metal and then bent it how the paint would crack and flake. I'm hoping this can be lessened with a bit of cold blue touch up.

So,

Whaddaya think?

Oh, and lastly, I'll go ahead and throw up a couple pics of the whole gun just so you can see what it looks like overall.

Side view.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair013.jpg

Bottom view.

http://i2.photobucket.com/albums/y43/DaveBulla/16gashotgunrepair014.jpg

Ty 357
May 4, 2010, 04:36 PM
So,

Whaddaya think?


I think I thoroughly enjoyed reading your post and a big welcome to this forum. I like to do stuff myself whenever possible, and even though the learning curve can be steep, expensive and sometimes painful....the satisfaction of learning something new and doing it myself is always well worth it.

Outstanding job sir!

janobles14
May 4, 2010, 10:13 PM
very nice! didnt know it was that easy (or making it look so)

gb6491
May 5, 2010, 12:13 AM
...I thoroughly enjoyed reading your post and a big welcome to this forum.
+1, great save on your shotgun.
Regards,
Greg

skeeziks
May 5, 2010, 11:00 AM
I'm happy for you...but, you have to realize one thing. The steel has now been stretched twice (once when it got dinged and once when you straightened it.) This area of the bbl. will never be as strong as it was. This is the reason most 'smiths won't try to remove dents.
So my advice to you is to shoot nothing but light, low-pressure 2 1/2" loads thru it. Don't ever let anyone sell you any bull about it being safe to fire longer shells in short chambers. Shooting shells that are too long for the chamber is a ticking time bomb waiting to happen. Someone (like the rube in the Cabela's gun room) might shoot cases of 2 3/4" without anything happening...and then some other guy might have one explode after only 2 or 3 rounds.
Good luck with your project and have fun.

NCsmitty
May 5, 2010, 12:13 PM
It was a very good read, thanks. If you ever consider a reblue, use some fine scotchbrite in different grits to blend the marks prior to a final polish for bluing.

That's a fine old shotgun.

NCsmitty

Howard Roark
May 5, 2010, 04:32 PM
Outstanding post. Congratulations on a job well documented and done.

CelticArmory
May 5, 2010, 10:00 PM
You did a real good job there. As far as the discolored spots go, I think I may understand what happened. I have a background in aviation structures (sheet metal) and I've seen similar effects on metal as it's bent. The surface condition changes when you bend metal either stretching or compressing depending on the side of the bend. It's like the surface gets a bit rough as the molecular structure is disturbed by the bend and straightening process. This effect is more visible in softer metals like aluminum and copper. I think a good fix would be to completely reblue the shotgun and have those two spots polished to match the rest of the barrel.

Marcus

Marlin 45 carbine
May 6, 2010, 10:10 AM
have to admire your thouroughness and ingenuity. nice shotgun, although I prefer a 20 or the big 12 3" the 16 is about as good as it gets for quail and rabbits and grouse.

justashooter in pa
May 6, 2010, 02:26 PM
nice work for a parts changer (i was a P mechanic on allison, lycoming, and pratt turbines for rotary, specialising in fuel systems).

i have a set of brass inserts that are adjustable for final diameter and have done similar work.

as for the final strength of the repaired tubes, no worries, especially so far from the chamber. as for shooting full shells in short chamber, you will get a pressure spike every time as the flare crimp unfolds into the forcing cone and the wad attempts to push through the obstruction. this spike can be double working pressures, or more.

B&PUSA is my source for short shells, offereing 2 and 2 1/2 in a variety of gauges. i use these mostly in 12 gauge belgian hammer doubles of dubious vintage.

just for fun i load all brass shells with black powder. midway offers these in 12 gauge. not sure about a source for 16 gauge.

sideways
May 16, 2010, 11:20 AM
I think you should hang it on wall and purchase a real shotgun. I'd be reluctant the run any kinda load through and surely would not ever let my children or grandkids shoot, no way.

Ian Sean
May 16, 2010, 11:42 AM
Whaddaya think?

One of the best "do it yourself" threads I have ever read and top notch pictures. Really good job on the shotgun. I have seen a few shotties with dents removed, yours is one of the best.

Great post.

BBBBill
May 16, 2010, 02:42 PM
For the naysayers, removing dents in shotgun barrels is a well established procedure that, when done correctly, is perfectly safe. I own the expensive hydraulic jacks for doing that repair. I see nothing wrong with the OP's fix.

Clemson
May 20, 2010, 11:07 AM
Good job, Dave!

For what it's worth, plain old 12L14 steel will work fine for the mandrell if you have to make another.

Clemson

Dave Bulla
May 22, 2010, 01:54 AM
Just saw this has been active again recently and noticed the couple of comments about how bad it is to repair a dent or that it's not safe. Anybody have any actual experience to back this up? I've been working with metal in daily maintenance of aircraft and industrial applications for about 26 years now and while I'm certainly no metallurgist I've certainly seen examples of fatigue, work hardening, fretting, corrosion etc etc not to mention structural failures from many different types of causes. I've also seen metal extrusion and forming processes, swaging processes, blacksmithing and other applications where metal is bent, shaped, tortured, altered, tempered and what have you. I understand that there are limits to what can be done and changes to structural strength caused by bending, heating, tempering etc. What's the real skinny on my repair?

As far as I'm concerned, metal is a malleable material fully capable of being bent within certain limits with no ill effects. Effects yes, ill effects no. I couldn't say exactly how many degrees of bend were present in my dents but it was surely less than 20 degrees. Possibly less than 15. That's not much.

Also, I'm certainly no gunsmith but I'm a fairly observant fella and I've been around a lot of guns in my lifetime and I've seen a bunch of old shotguns with dents in the barrels that were still being shot regularly. Most had a story to go along with the dent if I cared to ask. Many times it involved somebodies Grandpap many many years ago and that dent had been there a LOOONG time and the gun was working just fine. I've also seen quite a few guns where there was evidence that a dent had been raised by a method similar to mine. In fact, I've got an old 12 gauge hammer gun that appears to have had a dent raised at some point though the results are not quite as good as mine. No problems there either. Being a hammer gun, it's possible that dent was fixed several decades ago.

In all my years of being around guns, I don't recall ever hearing a story of a barrel failure due to a repaired dent. I have heard of and seen bulged barrels caused by shooting guns with severe dents in an attempt to shoot the dent out with a slug but that's just stupid in my book. There's a big difference between using a tool and a hammer to gently push a dent back flat and using a slug with thousands of psi of pressure behind it to try to shoot a dent out so I don't feel the two can be fairly compared.

Anyway, just wandering if anyone actually had any facts to back up the "danger" of raising a dent. And I don't mean from a lawyers point of view that might keep a gunsmith from doing it.

I'm listening....

Clemson
May 22, 2010, 06:36 AM
Dave, barrels have been salvaged that were not just dented -- they were bent at bizzare angles. The repair was to whack the barrel across a log until it straightened out!

Clemson

Dave Bulla
May 23, 2010, 12:06 PM
The repair was to whack the barrel across a log until it straightened out!


Hmmmmm, now you've got me thinking again about a gun I saw a couple weeks ago in a gun shop.... It's an older Ithaca model 37 pump in 20 gauge that seemed priced ridiculously cheap at something like $125 until I noticed the tag says the barrel is bent. Sure enough when I looked down the barrel it's bent pretty good (bad?) to the right. The muzzle is probably 1/2" out of line with the receiver. Just a long gradual bend like maybe somebody fell with the gun and landed on it but probably on soft ground. I wonder how hard it would be to straighten???? Maybe make a long version of my tool that would fill the whole barrel from chamber to choke and give it the same treatment.

Clemson
May 23, 2010, 12:54 PM
I saw an explanation by gunsmith Roy Dunlap that the barrel is held by the end and simply hit on a wooden surface (i.e., a log) until is straightens up. Apparently the theory is that the steel "wants" to realign to the form that it had when it was produced. You are only out $125 if it does not work (actually, offer $65 and see if he will take it). For what it's worth, I was able to buy a 28" vent rib barrel for an older (1947) model 37 in 20 gauge about 6-8 years ago from Numrich. It was brand new. It did require fitting as the older ones are not drop ins, but the fitting was accomplished with needle files.

Clemson

rmfnla
May 24, 2010, 07:03 PM
This is true; I used to wack bent shotgun barrels on the door jamb of my shop to straighten them. There is a technique to this.

If you look down any shotgun you will see 5 "rings" of light. If the rings are concentric the barrel is straight; if they are not, their displacement will tell you where the barrel is bent.

The trick is you wack the barrel on the bend, which sounds counter-intuitive, but actually "springs" the barrel back into alignment.

I don't 'smith anymore so I haven't done one of these in years, but I remember enjoying great success with that technique. The guy who taught it to me said you could always tell a good gunsmith by the marks on his door jamb...

Nice job on the SXS, BTW!

skeeziks
May 24, 2010, 08:52 PM
How did this thread get so off-topic? We were talking about dented barrels, not bent barrels. ~ ;)

BBBBill
May 24, 2010, 11:59 PM
I use a barrel press to straighten bent barrels. Mine was purchased from Brownells, but a handy fellow could make one using the picture in the catalog as a guide. I fear that I would be a total failure using the "whack-it-on-the-door-jamb" method.

rmfnla
May 25, 2010, 10:51 AM
How did this thread get so off-topic? We were talking about dented barrels, not bent barrels. ~ ;)
First time on THR..?

fecmech
June 2, 2010, 05:45 PM
Dave-(another A&P here) I would not worry one bit about the safety of that barrel. Shotgun powders are relatively fast and and the time pressure curve is pretty steep decreasing once you leave the chamber area. Great job on the dents.

TonyT
June 6, 2010, 01:40 PM
I thorouhly enjoyed your description of both how the dent occured and the remolval process. welcome to the forum.

orionengnr
June 8, 2010, 07:33 PM
Just another A&P checking in.
I thoroughly enjoyed the story of both the original damage (that is tto say, the story was well told even if the outcome was an unhappy one) and especially the well-thought-out repair process.

The "bumping" of the outside of the barrel shows some understanding of metal and how to put it into motion with minimum force required and minimum trauma inflicted.

The use of the Scotch tape was ingenious as well.

I love a happy ending--Great job!

SleazyRider
June 8, 2010, 07:50 PM
Best doggone post I've read in a while, and I can't wait to hear about more "home smithing" from you. Living proof that craftsmanship and ingenuity trump certifications anyday.

Dave Bulla
November 23, 2010, 07:38 PM
Up for Bob C.

sophijo
November 23, 2010, 07:55 PM
Great thread Dave, but what does that mean?

Dave Bulla
November 24, 2010, 04:42 PM
Thanks sophijo,

"Up for Bob C" was me making an entry on this old post to bring it back to the top of the list so my friend Bob could find it. I'd told him about it but didn't remember the exact title I'd posted this under so I looked it up myself and brought it up where he could find it easier.

Same as TTT which is "to the top".

Milanodan
December 22, 2010, 09:25 AM
>"The steel has now been stretched twice (once when it got dinged and once when you straightened it.) This area of the bbl. will never be as strong as it was. This is the reason most 'smiths won't try to remove dents."<

Ever heard of "work hardening"? The dented area is now the strongest area of the barrel!

BTW, look up "Luders lines/bands" and "stretcher strains" for info on why the dented areas are visible.

SleazyRider
December 22, 2010, 10:37 AM
Metal hardness and metal strength are 2 different properties. I don't believe there's been a significant change in either, however.

Milanodan
December 22, 2010, 11:18 AM
Metal hardness and metal strength are 2 different properties. I don't believe there's been a significant change in either, however.
Ever seen a Wilson, etc. hardness conversion chart, where the ultimate tensile strength (UTS) is the last column on the right?

Hardness, especially of steel, correlates very well with UTS, but not so much with yield strength (YS). Doesn't matter, because YS increases faster with work hardening than UTS.

I agree that for the minor amount of deformation in the subject barrel the strength wouldn't increase by much, but that area is slightly harder/stronger than the rest of the barrel.

Pete D.
December 22, 2010, 11:19 AM
Work hardening also makes the metal brittle -that's why a wire can be made to break by bending it back and forth.
I'd not worry about that issue on this barrel.
Pete

Milanodan
December 22, 2010, 11:28 AM
Yes, if taken to an extreme. Not an issue for even severe denting of a barrel, unless it's done several times.

PT1911
December 22, 2010, 11:42 AM
hell of a good job... most would have given up on that one without an attempt to salvage it... Kudos.

Seedtick
December 22, 2010, 10:45 PM
+1 Dave Bulla

Great post!

I hope to never have a damaged shotgun barrel but if I do maybe I can use the information presented here to remedy it.

Thank you, Sir.

Seedtick

:)

Waywatcher
December 23, 2010, 09:33 AM
Very cool, thanks for sharing!

I also think this gun is perfectly safe to use. Quick Shotgun powder fully burns in like 10" if I recall correctly. Naturally, peak pressure would be sometime before.

Personally I wouldn't try to blue it at all.

supercopjason
December 23, 2010, 12:37 PM
If your worried about the metal after the dent repair drop it off at a Cryogenics shop. Find one that specializes in automotive parts and you may get it done pretty cheap. I pay 30 bucks per setup and can do quite a bit.

Old Guard Dog
December 25, 2010, 01:52 PM
I was always taught that a dent can be fixed safely, but a buldge should never be fixed, since the metal has been stretched, and will be weak if moved back into shape.

Dave Bulla
January 11, 2011, 04:27 AM
Well howdy!

I've been gone quite a while and hadn't looked this thing up for quite some time.

Glad to see some positive replies to my questions about the safety of the repair. Pretty much all of what you are saying is about what I figured before I started this project. I always figured that yes, bending metal work hardens it and if you do it repeatedly it will break but this little bit of movement didn't seem like it would be an issue.

Milanodan said "BTW, look up "Luders lines/bands" and "stretcher strains" for info on why the dented areas are visible."

Thanks for the tip. I'll check them out. Always willing to learn something new.

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