need a fix

[david50]

I have a smoothbore barrel which has had the ventliner hole drilled out too large for even a 3/8 size ventliner. my question is can the hole be filled by welding some how and then redrilled.

[A.Merrill]

    There is a couple of ways to fix it. Go ahead and thread the hole and make a ventliner to fit or just make a plug thread it screw it in then redrill for the ventliner.....good luck.   Al

[david50]

it already has a 3/8 hole drilled in it,if I go any bigger it will go beyond the flats

[david50]

what size tap would I use for a 3/8 hole,i could use a stainless set screw to make a liner

[Acer Saccharum]

Cut the barrel off, re-breech, and re-vent. So you lose an inch? Better safety factor than a funky double liner or a weld.

[david50]

Acer I don't have the equipment for anything like that. here is what happened. I bought a smoothbore sight unseen when I got it the vent hole was way out of line with the pan,the only way I could drill it for a vent liner and cover the existing hole was to go with a 3/8 liner. well guess what I did,i used a 3/8 drill bit instead of a size Q. yea I know,dumba@@ attack.

[flehto]

On one of my first builds, the ctrbr for a shouldered TH liner got "screwed up" so here's what I did. Made a short  copper rod that was a slight press fit w/  the bore,  placed it under the hole, took it to a tool welder and he filled in the hole.  Filed everything smooth, installed a new liner  and it's fired at least a 1000 shots since then. ......Fred

[billd]

I agree with Tom.  Cut it off, it's a safety factor.

Bill

[kutter]

I'd cut it off and do it over personally,,or have it done if you don't have the tools.
I'd rather not have the vent anyway.


Perhaps there is a standard metric size tap w/sufficiently fine thread that can be used in the already drilled 3/8d hole.
Stainless Metric threaded bolts are available and (maybe?) could be used then to make a vent.

FWIW (Metric) M11 X 1.50  thread uses a standard US drill size 3/8" for a tap drill size (75% engagement)...

Just an idea to save any sort of oversize cut w/o going bigger yet.  But consider the safety above all in this case..

[D. Taylor Sapergia]

A patent breech could be made for the barrel.  In which case, the breech is cut off, threaded again, and a new breech made.

[Acer Saccharum]

If you don't have the equipment, get a new barrel. Sell the bum breech one on the ALR classifieds. There are plenty of guys who do have the equipment who can make a good barrel out of it. Or you might advertise in the classifieds for someone to re-breech it for you.

Safety, safety, safety....

But DON'T make a bomb out yours with concentric plugs. Some day that will blow out and kill or maim the shooter next to you. You will also think about this at every match. Or should think about this at every match. That alone would give me the willies, and I couldn't concentrate on my target.

[KentSmith]

Why not make a vent.  Tap to 7/16 X24or finer thread if available to you, with matching bolt, screw in bot, cut off to match outside eyeball inside to keep flush with bore, etc. and drill for a 5/64 vent. 

If you do not have the tools or do not want to go this route, buy a new barrel and replace the old one, but I would argue if you do not have the tools to make a vent liner, you don't have the tools to replace the barrel.

[david50]

if I drill a 7/16 hole it will be wider than the flat

[whitebear]

if I drill a 7/16 hole it will be wider than the flat

So What?  Time you do it as Kent Smith suggested and refinish the barrel it wont be noticeable anyway.

[david50]

if I drill a 7/16 hole it will be wider than the flat

So What?  Time you do it as Kent Smith suggested and refinish the barrel it wont be noticeable anyway.

I would also be drilling into the breech plug.

[Acer Saccharum]

So What?  Time you do it as Kent Smith suggested and refinish the barrel it wont be noticeable anyway.

Please don't push someone toward a decision they're not ready to make.

[eddillon]

So What?  Time you do it as Kent Smith suggested and refinish the barrel it wont be noticeable anyway.

Please don't push someone toward a decision they're not ready to make.

Well said, Tom.  We don't know what has been completed on the build.  Are the tenons in place?  Have the slots been cut for the barrel keys?  If so, are escutcheons inletted?  All of these would definitely influence the decision.

[Acer Saccharum]

...as California Ed says, we sometimes need more info before the 'right fix' can be suggested.

We are, in general, a very helpful lot, with your genuine safety and building satisfaction at heart.

[david50]

wont cutting the breech end back an inch or so make for a loose fit in the stock,not to mention putting the under lugs out of line.

[eddillon]

wont cutting the breech end back an inch or so make for a loose fit in the stock,not to mention putting the under lugs out of line.

In your case, two options:
1. New barrel
2. Patent breech  on your shortened barrel.  barrel cut to length so that barrel+ patent breech = old barrel length.
   THE TANG CAN BE CUT OFF THE OLD BREECH PLUG AND WELDED TO THE PATENT BREECH
If you don't have the parts, confidence, skill and tools to do this, your choice is option 1.

[Captchee]

My concern with making a larger  flash hole line or a plug would be that since its larger then the flat , its then going to transition into the  next two angled flats and thus a thread or two will end up being exposed .
 If the barrel is a swamped barrel then yes cutting it back  would make a little issue with the inlet.
 I guess it would all depend on what one wants to do as that also could also be remedied by   making a special plug that would make up the difference and thus place everything right back where it needs to be . But that would also be some work if one doesn’t have the tools   

[david50]

well I have pretty much come to the conclusion that the only way out is a new barrel. does any one have one they would be willing to trade,plus cash of course. it would have to be a 44" in order for the under lugs to match up

[whitebear]

I apologise for making a thoughtless reply.

[David Rase]

Let me float this idea to you and the forum.  A Colerain barrel is breeched to 1/2" depth.  You need to open up the touch hole liner to 7/16"x20.  1/2" plus 7/16" equals 15/16".  What if a breech plug and tang was made with a 1" long set of threads and a powder chamber (English style) drilled into the plug far enough back from the face to accommodate the touch hole liner.  Put the barrel in a lathe and single point the minor diameter of the thread pitch to a depth of 1" then tap the existing threads to the new depth of 1".  Install the breech plug/tang seating the face of the plug and the tang.  Drill and tap  7/16"x20 threads and install a stainless bolt that has been coned out on the inside.  That made me tired just typing the process down.
David    

[Acer Saccharum]

Dave Rase, dave50 says he doesn't have the means to do this work. So HIM doing this is out of the question. This is a very good suggestion for someone with the tools or a lot of money.

You can still cut the breech off , and install new lugs 1" ahead. Seen this done on many old guns. File the old ones off flush. I am happy to re-breech this for you, but I will cut off what I need to do the job. Just let me know by PM if you want to do this.