Welding Up A Dovetail

[Uncle Grinch]

I've got a sporter Mauser that has a dovetail cut on the underside of the barrel. While it is hidden, it bugs me and I'm considering having it TIG welded up. The guy I'm planning on using is not a gunsmith, but is a professionally trained welder and knows his stuff. Still, I want to be able to offer any advise to him that I can. The dovetail is 0.13 inches deep and the barrel is 0.989 inches in diameter with a .358 bore. I suppose I could always fit a dovetail plug and file it to a press fit, then contour to the barrel.

I suspect this was originally for a recoil lug as it's about 5 inches from the chamber.

What little I know is that TIG is the preferred method as it generates less heat. Any thoughts or comments??

[theperfessor]

I would leave it alone. The chances of warping the barrel from a cosmetic repair would be too large in my mind to justify trying it. But that's just my opinion.

[johnnybar]

I've got a sporter Mauser that has a dovetail cut on the underside of the barrel. While it is hidden, it bugs me and I'm considering having it TIG welded up. The guy I'm planning on using is not a gunsmith, but is a professionally trained welder and knows his stuff. Still, I want to be able to offer any advise to him that I can. The dovetail is 0.13 inches deep and the barrel is 0.989 inches in diameter with a .358 bore.

I suspect this was originally for a recoil lug as it's about 5 inches from the chamber.

What little I know is that TIG is the preferred method as it generates less heat. Any thoughts or comments??

I've been welding since 1976 and no matter how careful, TIG generates enough localized heat to alter the barrel's heat treatment and in addition, warpage of the barrel will occur, even if only slightly. 5" from the chamber is still a very high pressure zone...don't do it. Install a finely fitted dovetail plug in the slot. Emery strip and buff it to blend with the existing finish. Do it well enough and it will look very nice. If you want to take the lazy Sunday afternoon approach...put JB weld putty in it and sand to match the contour then Sharpie or paint black. If you don't like it, no harm. Just dig it back out. I have fixed trigger guards, that store clerks trashed, using JB. Several times when drilling out trigger locks, because of lost keys, they drift the bit off into the guard. I have got some rediculously cheap rifles thanks to their goof ups.

[mongoosesnipe]

I wouldn't weld the barrel you will end up with a week spot and then you will need to refinish that area anyway so I would just plug it if it bugs you that much I would probably just use the jb weld method

[scb]

+1, don't weld it, it will not do the barrel any good. If it really bothers you that much you can make and carefully peen in a slot blank. If done properly and the barrel's refinished (which I'm guessing you were planing on doing after welding) the "repair" will be hardly visible.

[MBTcustom]

I had a job to do once. It involved drilling a hole through some Thompson case shafting lengthways. Basically, I needed to remove all the soft material from the inside of the shaft. Once this operation was complete, the shafts had warped. In order to straiten them, I took a torch and heated a spot until it turned purple. That would warp the shaft (either towards or away from the spot, I can't remember) and effectively straiten the shaft.
Applied to your situation, where you have what is supposed to be a strait tube, what do you think the result will be?
Hence, I wouldn't do it.

[Uncle Grinch]

After entertaining everyone's opinion and experience, I'm not going to take a chance on warping my barrel. Sounds like a fitted plug and a little JB Weld will be the most prudent way to go.

That's what I like about this website.... there's a lot of knowledge here and it's so willingly shared!

Thank you for the info.

[LtFrankDrebbin]

Good choice mate, don't go there. I too weld for a living and there is no way I would attempt to weld a gun/ rifle barrel. The risk of warping or creating a heat affected zone ( annealing or over hardening) are far too great.
The most heat I would ever consider applying to a barrel would be soft solder with the lowest melting temp avalible. (have done it with great care to fit front sight in oversize dovetail)
With the technologies that go into products like JB weld, they probably have a far supierior strength than solder anyway.

[oldred]

As others have said welding is a very poor option here for many reasons but warping the barrel is not necessarily one of them. I have for many years repaired shafting for mining/construction equipment and pumps with most of these shafts and tubes requiring closer tolerances for straightness than rifle barrels so I thought I would mention the technique since welding on a barrel could be necessary at times, although I would question the wisdom of welding over or near the chamber. The trick is to clamp the barrel in such a manner as the pressure points of the clamping device is butted up as close as possible against the finished edge of the welded area, if the clamping device is even an inch away on either side of the weld the barrel/shaft will "spring" when released from clamping pressure due to the stress induced into this area. By clamping right against the edge of the weld the stresses will be confined to the weld itself and little if any detectable warpage will occur. I have used this method for many years on shafting and tubes many times longer than a rifle barrel with no problems so if done properly a barrel can be welded and kept straight. Having said that welding is still a "last ditch effort" IMO because even if the barrel can be held straight there is still the problem of bore distortion and of course possible loss of strength due to tempering changes from the heat.



EDIT: After rereading what I wrote it could look like maybe I was trying to disagree with everyone's suggestions about warping the barrel from welding but that's not what I meant. The advice that was given by others is spot on and a barrel could indeed easily be warped severely by even a small welded area such as that dovetail and I in no way meant to disagree, rather I was just pointing out that it is sometimes possible to perform a welding operation such as that given the right conditions and procedures.

[firebrick43]

Encores and contender barrels are welded to the lugs under the chambers without major issues although some state that they can feel the difference in the haz area while chamber reaming many highly accurate and durable barrels are welded in the high pressure area so that's not a concern further down the barrel. Also ALL barrels are warped! Thats what adjustable sights are for! What ever tight fitting device originally fitted into the dovetail warped the barrel as well when installed!

The only concern I would have is to much heat causing scaling on the rifling. Easy kept at bay by coating the bore area adjacent to the weld with heat paste and welding small area and letting it cool(with a slip fit dovetail filler made of the same steel). I would personally just solder a slip fit and slightly proud plug, draw file to shape, reblue/refinish and use some solder black to touch up the line.

[oldred]

Also ALL barrels are warped!

They certainly are! IMO too much importance is placed on barrel straightness but the thing is it really don't matter all that much. A barrel can have a curve in it and as long as the sights can be adjusted far enough it should not matter (I am talking a few thousandths of an inch NOT a bend that is visible), just because the barrel has a slight bend or curve does not mean the projectile will travel in a curved path so all that's required is that the sights be aligned with the path of trajectory after the bullet leaves the barrel, it matters very little (within reason of course) what path the bullet takes to reach the muzzle. What is important is barrel stability, whatever variation there is between the chamber and the muzzle must remain constant from one shot to the next in order to provide good accuracy.



I have seen several makes of barrels that have had lugs welded to them near or on the chamber area over the years but I have always assumed these were welded before chambering which would prevent the chamber or bore being distorted but of course would do little or nothing to prevent heat effect on tempering strength. I have wondered in the past about the T/C barrels if they are maybe heat treated or stress relieved after welding.

[uscra112]

Barrels with localized stress in them for whatever reason tend to warp all over the place as they heat up from firing. For a hunting barrel that does one or two shots from cold, it's not too much of an issue. Any barrel that is expected to shoot a 5 shot group - another story.

[Hardcast416taylor]

I've been welding since 1976 and no matter how careful, TIG generates enough localized heat to alter the barrel's heat treatment and in addition, warpage of the barrel will occur, even if only slightly. 5" from the chamber is still a very high pressure zone...don't do it. Install a finely fitted dovetail plug in the slot. Emery strip and buff it to blend with the existing finish. Do it well enough and it will look very nice. If you want to take the lazy Sunday afternoon approach...put JB weld putty in it and sand to match the contour then Sharpie or paint black. If you don't like it, no harm. Just dig it back out. I have fixed trigger guards, that store clerks trashed, using JB. Several times when drilling out trigger locks, because of lost keys, they drift the bit off into the guard. I have got some rediculously cheap rifles thanks to their goof ups.

My thoughts exactly, been there and DONE that.Robert

[scb]

They certainly are! IMO too much importance is placed on barrel straightness but the thing is it really don't matter all that much. A barrel can have a curve in it and as long as the sights can be adjusted far enough it should not matter (I am talking a few thousandths of an inch NOT a bend that is visible), just because the barrel has a slight bend or curve does not mean the projectile will travel in a curved path so all that's required is that the sights be aligned with the path of trajectory after the bullet leaves the barrel, it matters very little (within reason of course) what path the bullet takes to reach the muzzle. What is important is barrel stability, whatever variation there is between the chamber and the muzzle must remain constant from one shot to the next in order to provide good accuracy.

If a barrel is bent, say to the left, how does one shoot accurately past the distance it's sighted in for? That is why barrels are straightened. If the maximum range one fires is 100 yards then the yes the effect is probably minimal.

[nanuk]

If a barrel is bent, say to the left, how does one shoot accurately past the distance it's sighted in for? That is why barrels are straightened. If the maximum range one fires is 100 yards then the yes the effect is probably minimal.

the barrel is bent, the sights are set

but the bullet does not continue on the curved path of the bent barrel... it is still a straight line.

so you fire the shots, line up sights to they point at the impact zone... same as always.

I bought a never fired takeoff from a Savage, 7-08, and the bore is "Noticably" off center at the muzzle. I have to assume the bore is not straight. But I can't see it mattering.

some pretty good groups were fired years ago with hand straightened barrels. I'd bet a DoubleDouble they weren't perfectly straight.

but also, why add more stress and bend to a barrel, when there are other options?

[oldred]

Think about it, the bullet will travel in a straight line (not counting normal drop of course) so all that is needed is for the sights to be aligned with with the line of bullet travel not the bore since the bullet travels in a straight line once it exits the barrel. The sights would still be aligned regardless of range change (again not taking into account normal drop) since we are talking about a straight line, thus if for instance the "bend" is only left or right then the sights would need to be adjusted to align with the path of the bullet after it leaves the muzzle and this path would not change since we are talking about a straight line. And yes I know barrels are straightened but few if any are truly straight, as I pointed out I was only talking about a few thousandths anyway not a bend you could see, even still a huge radius could theoretically be sighted in if the sights could be aligned. The bottom line it's sight alignment with the trajectory of the bullet that matters and the bullet couldn't care less where in the bore it starts out.

Even the military has tried curved barrels, here is an atachment for the M1 carbine.

http://www.gunsinternational.com/Hinden-Fleishman-Curved-Barrel-Extension-for-the-M1-Carbine.cfm?gun_id=100290664



This was a Russian effort,

http://www.ppsh41.com/serge3.htm


If a tiny bend of only a few thousandths was a problem then these guns with these extreme angles would be worthless as far as the point of impact changing with differing ranges, if that were in fact the case then with these extreme angles the point of impact would change wildly with even a few feet of range change if that really was a problem but it's not. Then of course there was the famous German curved barrel assault rifle "The Krummlauf" that had a 90 deg bend but that one relied on a periscope for sighting. The downfall of these rifles was not inaccuracy, that was not a serious problem, but rather extreme short barrel life from rapid bore wear in the bend, I think I read somewhere that the Krummlauf could only fire a couple hundred rounds before ruining the barrel.

[oldred]

I bought a never fired takeoff from a Savage, 7-08, and the bore is "Noticably" off center at the muzzle. I have to assume the bore is not straight. But I can't see it mattering.


A few years ago I was looking at some ML barrel blanks in a catalog, don't remember the brand but I am thinking maybe this was Dixie Gun Works, and it was pointed out that the barrels had varying amounts of run-out of the bore on one end. It was then suggested that the off-center end be used for the breech end but they assured the customer that accuracy would not be affected regardless. That would certainly be true because it's the bore alighnment with the sights that matters and the bullet traveling down the bore has no idea where the outside walls of the barrel are located!

[bob208]

i haved been welding since 69. i can say i would and have done the fitted plug a few times. tried the weld method one time.at the insistance of the owner. it made a nice oval spot in the bore. i learned one thing from that. never again.

[firebrick43]

Bob, details? I could use a stick welder and completely fill it up with weld and it would surely mess things up. But I fail to see how a well fitted but not tight and use no filler. Weld five or six stacks of dimes and let cool before welding again.

Dovetails cause distortion of the bore any way. When handlapping barrels I could always feel where the dovetail was located. Once drove the front sight out and it felt looser than with the sight in. Many revolvers you can feel a tight spot where threaded into the frame.

[MtGun44]

+1 on what the perfesser said.

Bill

[W.R.Buchanan]

Grinch:

If this dovetail is on the underside of the barrel and the stock hides it?

Why not just leave it alone? If you can't see it, what difference does it make?

I can offer counseling if it buggs you that much.

Randy

[Uncle Grinch]

Grinch:

If this dovetail is on the underside of the barrel and the stock hides it?

Why not just leave it alone? If you can't see it, what difference does it make?

I can offer counseling if it buggs you that much.

Randy

Thanks Randy.... yeah, I'm one of those people. A few whiffs of 2400 combined Felix Lube seems to help.

[John Taylor]

I specialize in barrel repair and have welded up many barrel dovetails and screw holes when installing a liner. What has failed to be mentioned is that all welds shrink and will cause a tight spot in the bore. The warping thing is usually not a problem if you let the barrel cool slow, it can be pushed back to strait. Don't try to rebore a welded barrel unless it has been normalized, could wipe out a reamer and rifling cutter.

[Jammersix]

Getting back to the original poster, I have one question. It may be a side issue, so I'm sorry if this is off topic. I don't understand the advantage of using a welder that isn't a gunsmith. Why would you do that?

As many of the posts have pointed out, there are many reasons why you wouldn't want to weld a barrel unless you had to, so I don't see why you wouldn't use someone who understands all the implications of welding.

[Uncle Grinch]

I went back to the fellow I bought the barreled action from and he found the recoil lug that goes in the dovetail.... my dilemma is solved.

I had just about made my mind up to plug or JB Weld it up.

[theperfessor]

All's well that ends well!

[nanuk]

... I have one question. It may be a side issue, so I'm sorry if this is off topic. I don't understand the advantage of using a welder that isn't a gunsmith. Why would you do that?

... so I don't see why you wouldn't use someone who understands all the implications of welding.



I think the thinking is not all welders are gunsmiths, and not all gunsmiths are welders!

use the Professional who is trained in the specific field of industry to do a specific job.

I would guess the number of cross trained welders/gunsmith/machinists are few, and the really good ones are even fewer.

[KCSO]

Some folks lern the hard way... Many years ago I wanted to erase the warnings from a M/L barrel and a buyy said,"Bring it over and I'll tig the letters right off that dude". When he was done the barrel looked like a corkscrew! I had to use it for scrap iron and rebarrel the gun. Cut a well fitted dovetial slightly oversize and gently peen it and draw file and refinish and it will never be noticed.

[JIMinPHX]

What little I know is that TIG is the preferred method as it generates less heat.

Where did you hear that? As far as I know, TIG runs at a higher temperature than some other common welding processes.

[W.R.Buchanan]

Jim, the temp is higher but the heat is more localized, as a result the heat affected area is much smaller with TIG, and as a result the warpage is considerably less.

however for this application it will still ruin the barrel.

This is just not a good idea unless you want to spend a life time lapping the dimple out of the bore or straitening the barrel after you weld it.

Randy

[1616s16]

love good old j b
1616s16

[johnnybar]

Encores and contender barrels are welded to the lugs under the chambers without major issues although some state that they can feel the difference in the haz area while chamber reaming many highly accurate and durable barrels are welded in the high pressure area so that's not a concern further down the barrel. Also ALL barrels are warped! Thats what adjustable sights are for! What ever tight fitting device originally fitted into the dovetail warped the barrel as well when installed!

The only concern I would have is to much heat causing scaling on the rifling. Easy kept at bay by coating the bore area adjacent to the weld with heat paste and welding small area and letting it cool(with a slip fit dovetail filler made of the same steel). I would personally just solder a slip fit and slightly proud plug, draw file to shape, reblue/refinish and use some solder black to touch up the line.

This is for the johnny come lately's that may take away some thoughts for their projects: There are lots of factory barrels that are factory welded,heat treated, chambered, then possibly bore/chamber polished...as in shotguns. Repeating the process in a home or local welding shop is way different and would be considered an experimental process. Who wants to be a guinea pig?