I would like my next build to have a swamped barrel and would appreciate some advice on fixing underlugs, particularly at the thinner section of the barrel. The two methods usually employed each appear to have drawbacks; dovetailing could leave a very thin amount of metal between the grooves and the dovetail; soldering, especially silver soldering, requires heating the barrel to a high temperature locally. I don't know whether heating the barrel does cause a problem but some manufacturers (all?) heat their entire barrels to relieve stress. Could soldering create stress or deformation in the barrel? What worked (and didn't work) for you? Also, how did the early gunsmiths attach these underlugs??
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How best to fix underlugs to a swamped barrel?
- Thread starter MikeMyDay
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Unless you have a VERY slim barrel, all can be dovetailed. If necessary, the one on the waist of the barrel can be soft soldered on. No need for high heat and silver solder. The under lug just holds the wood to the barrel, and the one in the waist isn’t under much pressure.
Pete G
76 Cal.
I always use a shallow dovetail about 1/16 or less, even on .50 cal B weight.
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Mike,
Here are two methods for rear sight and loops: 1. First of all in my opinion you do not need silver solder. I use "Sil-Tin, a low temp, high strength soft solder.(14,000 psi.) It will not be equal to silver solder, but I have never had an issue. 2. The breech has the most barrel pressure and of course the rear sight is a concern for barrel integrity. I use a jewelers saw and remove about .022 to .025 barrel flat. A normal 3 corner file is too blunt for such a small area to get a crisp / \ angle for the sight base. I am not telling you how much metal to remove from your barrel, just telling you what I do.
Hope this helps.
Flintlocklar
Here are two methods for rear sight and loops: 1. First of all in my opinion you do not need silver solder. I use "Sil-Tin, a low temp, high strength soft solder.(14,000 psi.) It will not be equal to silver solder, but I have never had an issue. 2. The breech has the most barrel pressure and of course the rear sight is a concern for barrel integrity. I use a jewelers saw and remove about .022 to .025 barrel flat. A normal 3 corner file is too blunt for such a small area to get a crisp / \ angle for the sight base. I am not telling you how much metal to remove from your barrel, just telling you what I do.
Hope this helps.
Flintlocklar
Dane, Pete and Larry, Thanks for the responses, your experience might prevent me from ruining a barrel. FYI I tried to silver solder an underib onto the barrel of a GPR without success and with a big mess to clean up. I worried that the bore might be affected but it is not out of round. Whether the barrel is still straight is another matter and I'll have to find a way of checking (without removing the breach block). This first rifle was the one on which I wanted to learn by my mistakes, and there were plenty. I hope I have learned!
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Get a good straight edge and just check it against that, assuming the barrel is a parallel one. If it is not obviously out of 180 deg, you really need to see how it shoots to verify your concern. Unless the barrel was "RED" hot, quenched in water or liquid, my guess it is OK.
Flintlocklar
Look at track of the wolf staples for the low stress center lug could be just what you need
tenngun, I'm a bit leery of drilling in the thinnest barrel section. How deep would I need to drill for the staples?
rich pierce
70 Cal.
Based on decades of reading posts, more barrels have been ruined by installing staples than any other operation. Of course if you have a milling machine you can control depth accurately.
1) don’t buy a thin waisted rifle barrel. It will be whippy and susceptible to changes in point of aim.
2) solder lugs into a small slot or very shallow dovetail. This is how lugs are installed on original, thin-walled fowlers and trade guns.
1) don’t buy a thin waisted rifle barrel. It will be whippy and susceptible to changes in point of aim.
2) solder lugs into a small slot or very shallow dovetail. This is how lugs are installed on original, thin-walled fowlers and trade guns.
Thanks Rich. The barrels I'm considering are Colrain 42" Classic American, either B weight 0.50 caliber or C weight 0.54 caliber. If I got my sums right the minimum wall thicknesses would be 0.120" and 0.109" respectively. Would either be whippy? Is there a general rule of thumb regarding the minimum safe wall thickness of a barrel after cutting a dovetail?
rich pierce
70 Cal.
Mike, I think any less than 0.075” wall thickness is a little too thin. I’d see where the waist is and plan accordingly. Your front underlug should end up in the flare. No problem. It’s the second one from the muzzle you want to be careful with. Neither of those barrels are bench weight but should give good offhand and hunting performance.
Just about an 1/8 of an inch
I build the Lancaster LRs w/ a Rice .50m cal "B" weight X44" and the Bucks County LRs have a Rice .50 cal "B" weight X46". The bbl lugs at the waist are always soft soldered on....easy to do and the bbl lug w/ a .040 thick base has plenty of web. When soldering bbl lugs onto a bbl, the bbl is mainly heated...I use a Mapp Gas torch because propane is too slow.
Started using staples formed from nails when first starting out and when drilling the holes, used both the drill press spindle stop as well as a drill sleeve. To get maximum hole depth, the angle point drill has to followed w/ a fat bottom drill. A lot of depth adjusting has to be done w/ a swamped bbl and found that dovetails were a lot easier and faster. .....Fred
Started using staples formed from nails when first starting out and when drilling the holes, used both the drill press spindle stop as well as a drill sleeve. To get maximum hole depth, the angle point drill has to followed w/ a fat bottom drill. A lot of depth adjusting has to be done w/ a swamped bbl and found that dovetails were a lot easier and faster. .....Fred
Pete G
76 Cal.
On a large caliber swamped barrel... don't
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DO NOT install staples in the waist of a swamped barrel. They are very useful in a straight barrel, but need to be drilled way too deep to be set.
Also, 1/16” is waaaaaay to deep For any barrel, it’s just not necessary, .040 or .045 is plenty
Also, 1/16” is waaaaaay to deep For any barrel, it’s just not necessary, .040 or .045 is plenty
Never tried staples, but have used shallow dovetails, but usually soft solder them on. I repaired lugs on a gun with soldered lug that pulled off. Too small footprint in my estimation; replaced with a bigger one. Be sure to give a bit of room in the pin holes for barrel expansion fore and aft; that little bit of movement can put a lot of pressure on the lugs.
I'd stick with using dovetails and then peening the edges over, never had a problem .
old ugly
40 Cal.
i have a 54cal swamped colrain barrel, it was a parts assembled kit, the supplier had installed the dovetailes for the underlugs. i was concerned about the remaining thickness of steal between the bottom of the dovetail and the bore so i tried to measure it. the closest i could figure it is about .030" (the .030' thickness is a very small area because the bore is round and the dovetail flat on the bottom). i searched around trying to determine the structural safety of the barrel. there was no data that i could find of it being a possible structural problem. never the less i gave up worrying about it. i have shot the gun for over 10 years now with no issues. one thing i would say, im sure there would be a huge issue if a ball was short started at that point in the barrel.
if i were to do it again i i would use dovetails for all the lugs except the centre one which i think i would solder on.
OU
tom
if i were to do it again i i would use dovetails for all the lugs except the centre one which i think i would solder on.
OU
tom
Soldering on a lug was how Bill Raby did it on his you tube vid building a SMR with swamped barrel
For what it's worth, I once drilled a hole for a underlug staple thru the barrel wall on a swamped barrel. I forgot to reset the depth stop on my drill press.
Anyway, it poked a hole thru the barrel about 5 inches behind the muzzle.
Rather than throwing the barrel away, I cut off the damaged end and recrowned it. I then soldered on a regular T shaped underlug towards the muzzle and built a shorter rifle.
It didn't come out too bad but the barrel wall is rather thin at the muzzle, for a rifle.
I also soldered on the front sight rather than cutting a dovetail for it.
All in all, the gun turned out to be one of the nicer ones I've built.
Anyway, it poked a hole thru the barrel about 5 inches behind the muzzle.
Rather than throwing the barrel away, I cut off the damaged end and recrowned it. I then soldered on a regular T shaped underlug towards the muzzle and built a shorter rifle.
It didn't come out too bad but the barrel wall is rather thin at the muzzle, for a rifle.
I also soldered on the front sight rather than cutting a dovetail for it.
All in all, the gun turned out to be one of the nicer ones I've built.
