Can I tap my barrel for a breech plug, or do I need to use a lathe?

[docone]

I will be putting in a breech plug on an unthreaded breech. Can I use a standard tap, 5/8 8, or do I need to use a lathe for flat threads?
I ask as I have no access to a lathe without sending it out. If it is a simple thing, I will try it here.
I figuire a tap, then bottoming tap.

[Mark Elliott]

You can drill and tap a breech without a lathe.   They did that 200 years ago.   You just need to be careful about it and you will have to modify your bottom tap slightly to cut all the way to the shoulder.   You need to grind off the first two or three partial threads of the bottom tap.    

[docone]

That helps. I appreciate. Still thinking on it, I might send it out, but once my workshop is done, who knows....  Might just try it.
Thanks for the advice.

[Dennis Glazener]

That helps. I appreciate. Still thinking on it, I might send it out, but once my workshop is done, who knows....  Might just try it.
Thanks for the advice.

Do it yourself then you know its right. Not everyone properly breechs a barrel. The guys here will help insure you do it right then you can do the next one by yourself.

Here is a good thread to read http://americanlongrifles.org/forum/index.php?topic=29973.0
Dennis

[docone]

I am in awe at the profficiency of the folks here.
Back when I first started building, I had no one. I would call Hunter at Dixie for some advice once in a while.
I built a couple and used Bondo, Epoxy, and never fired them. I gave up.
Now, I forge through.
I appreciate all the experiences of everyone here.

[whetrock]

I've done it without a lathe, but it is hard to keep everything lined up.

In the old days, both the drilling and the tapping were done with tools that had non-cutting, centering pilots that fit the bore of the rifle. That helped keep everything lined up.

The difficulty is this: The bore, the breech hole, the internal shoulder, and the breech end (external end of the barrel) are all lined up (on the same axis or exactly perpendicular to that axis). So, if the threads are tapped on that same axis, then everything will stay lined up.

If the threads end up crooked—that is, out of alignment with the axis of the bore—then the plug may not align with the internal shoulder or the end of the barrel. It is possible to work on these two areas, so as to bring them back into alignment with the threads, but of course it is best all around to just keep everything lined up.

Like Mark said, you will need to modify some taps. If you need/want suggestions for how to do that, there are several of us who can offer advice. Just holler. Even the basic breeching for many of the production barrels can do with some "tuning".

[Old Ford2]

To tap a thread for a breech plug, is not terribly hard.
But first you must choose the proper tap for the bore in question, and the thickness of the barrel.
Once that choice is made you must find the proper drill size to drill the breech.
This operation "MUST" be precisely in line with the bore, not the slightest angle, or you will have a crooked tang, which is hard to correct.
It is not impossible to drill and tap without a lathe, but it does take experience, equipment, and patience.
If I was spending $200 on a barrel, I would want the breech to be correct.
A good machine shop can easily drill and tap the barrel for you in less than a 1/2 hour ( what ever that rate is?) but also he will have to know just exactly how deep, to drill and tap. That is you call, most breech plugs are drilled the same depth as the diameter of the threaded breech plug.
Yeah, I know, way too much information!
Fred

[Dphariss]

If you know what you need to do to make it right its not a problem. But you need to understand the hows and whys.
For example you need taps.
These are 3/4-16 but you get the idea.


If in doubt find someone who knows how. Unfortunately there are lots of people, including some barrel makers who have a somewhat limited understanding of how to properly fit a breech plug. If the barrel dimension allows they need to be set against a shoulder.

This is the plug that is fitted to the shoulder. Not that the grooves can be seen in the marking color of the breech face.
This results in the threads being sealed from the powder gases.



If not properly fitted you can end up with something like this 50 cal barrel with a 5/8-18 plug.






This job was done by the barrel maker. The vent liner install was by the "gun maker".


Dan

[Dphariss]

Another view of the taps.

Its very difficult to get a tap drill hole true with the bore and with a square shoulder without a lathe or a hand tool to square the bottom of the hole.
I have a tool I made years ago will see if I remember to take a picture and post it.
This is a circa 1820-30 breech plug. It had no fouling in the threads.


Dan

[Mark Elliott]

I should say that I know you can do it because I have done it on a test barrel, so to speak.    I needed a way to hold and protect fitted breech plugs while I forge out or weld the tangs.   I took a short piece of 1 1/4" wrought iron round; drilled a 1/2" bore  on the lathe and then hand drilled and tapped each end for a different size breech plug.    I would suggest you do the same thing.   Twist drills do not want to go straight, even in a lathe; so when you drill the hole for the breech plug,  a standard twist drill is going to drift a little off center.    Your job is to minimize this to the point that it doesn't matter.    I think a period, spade type, metal drill bit might be a little less likely to drift and I may make a couple of these, eventually, to try.   I any case,  I believe you can tightly breech a barrel by hand by fitting the breech plug to the shoulder you have.   

[P.W.Berkuta]

It would be best if you have a scrap section of a barrel to practice on first. If it don't work out for you then you will know quickly this job is not for you - then find a machinist and pay him to do the job this will save you a lot of headaches .

[Acer Saccharum]

I don't like tapping by hand. I start the tap, find it's crooked, try to straighten it a little, and find the tapping is chewing the breech end up a bit more than I like.

The old timers had a reamer with a pilot that would take the bore out to the right size for tapping. The tap would have a pilot that would keep it straight and centered on the bore. I would feel fine doing it by hand with those tools.

But modern taps don't have pilots. Modern drills don't have pilots. How can you start them straight without a machine?

If you have to drill the bore out to the right size for tapping, be darned careful trying to drill it with a drill press or worse, a hand held drill. If you're an old hippie, tie up your hair, you're going for a spin if you try to drill a barrel out with a hand drill. Or break your wrists.

I hate sounding like the grim reaper, but I just have to point out when something sounds dangerous to me. 

[KentSmith]

I have to second Acer on this.  I have tried and succeeded drilling out a pistol barrel cut from a section of a longer rifle barrel with a hand drill  but it was not an enjoyable experience.  I do not have a lathe and would probably do it again if I had to, but the torque is going to give you a hard twist for sure and keeping everything centered in such a situation is problematic.  A bench type drill press also has the same issue with the added fun of having the heavy drill press want to move.  It is worth the cost and convenience to take it to a machine shop and have them use a lathe.

[KentSmith]

Rereading this thread if the breech is already drilled and you have the proper taps....you can give it a try.  I have a bottoming tap and a std. tap with tapered threads.  I start with the std. tap and once it's going right I finish with the bottoming tap.  The time it takes though and getting it right.....

I check my fit on all breechplugs and if necessary use the bottoming tap to fully seat the plug.  You have to assume the work will be used a lot with the subsequent erosion if not seated properly per Dan's comment above.

[Dphariss]

To tap a thread for a breech plug, is not terribly hard.
But first you must choose the proper tap for the bore in question, and the thickness of the barrel.
Once that choice is made you must find the proper drill size to drill the breech.
This operation "MUST" be precisely in line with the bore, not the slightest angle, or you will have a crooked tang, which is hard to correct.
It is not impossible to drill and tap without a lathe, but it does take experience, equipment, and patience.
If I was spending $200 on a barrel, I would want the breech to be correct.
A good machine shop can easily drill and tap the barrel for you in less than a 1/2 hour ( what ever that rate is?) but also he will have to know just exactly how deep, to drill and tap. That is you call, most breech plugs are drilled the same depth as the diameter of the threaded breech plug.
Yeah, I know, way too much information!
Fred

The set up at the machine shop will not be cheap either, this is not something that can just be put in the machine and done. It takes someone who knows what he is doing and WHY. Machinists are not gunsmiths, trust me. I used to be the only gunsmith in a shop full of them.  If they do it RIGHT it will likely take 30-50 bucks shop time just to get the barrel properly centered much less bored and tapped.
If one is going to be a gunsmith then one needs to come up with the necessary tools. Just to MAKE the tools to breech a barrel without a lathe requires, you guessed it, a lathe.
Piloted drill or reamer? Now you need a pilot for every caliber for that thread size. Should be a removable pilot so they are interchangable.
And we need the lathe to make the sleeves for the pilots.
OR BUY an 11/16 counterbore (for 3/4-16) from a supplier like MSC
http://www.mscdirect.com/product/details/71011449
But it still needs a pilot and it should be fairly long 2 " at least, less than .001 under bore size and made of brass to keep things well aligned and not damage the bore.

How do I drill and tap a barrel?

I use a lathe.
I set the barrel up so the bore runs true are BOTH ENDS. Then I bore it with a boring bar.

Then I run in a taper tap with a GOOD LUBE. TURNING THE LATHE CHUCK BY HAND.



Then I finish with a bottom tap ground to really bottom. THEN I have to be careful not to run the tap into the shoulder and ruin the seal. If I do I have then fix that.
The funny part is that if you get a barrel with the breech installed you may need a lathe to fix the installation.
So in reality one is better off NOT having the barrel breeched since it could be so screwed up that it takes as long to fix as to fit the breech from the start.

If the threads are long enough and the breech fitted and vented like this

Then the bottoming tap with threads right to the bottom is less important. Its possible to rebate the plug threads 1 or 2 threads at the front as this plug was done. It still has a lot of thread engagement as can be seen.

I am supposed to be fitting a buttplate right now...
Dan

[Dphariss]

P.S. The counterbore needs to be turned carefully with a large tap handle. Cut flats on the shank close to the cutter.

Dan

[Mark Elliott]

I agree it would be better to have original tools with pilots, but I really didn't have much trouble drilling or taping wrought iron, and I did it in bench vise with a hand drill.   I took it real easy with a light touch until I got the drill fully into the bore.  Once I did,  the drills cut very quickly.   It was like drilling in wood.   Maybe my drills were duller or sharper than yours, but they were brand new at the time.   I have rarely used a drill press or lathe to tap and have never had much of a problem.   Maybe I am too stupid to know that I had a problem.  It wouldn't be the first time.

I do need to add that my purpose in breeching completely with hand tools was to pave the way for making a completely hand made wrought iron barrel.   I wouldn't think of breeching a modern barrel that was going to be a regular shooter without a lathe.    By the time, I get around to doing an actual barrel,  I will probably make a purpose built cutter and tap with a pilot.

[Steve-In]

You will need the proper tap drills too.  Using hand tools they will have to be ground right or they will grab.  Also since you will be using such a small portion of the drill the chances of going oversize are greater.  I don't know the price of drills and taps but I would guess the cost to have one done at a shop would be much less.  I am not saying it can't be done by hand just be aware of all that is involved.  Dphariss show the proper way to do it using a lathe.  No need to drill when you can bore and control the size.

[docone]

You know, it is such a priviledge to be on a site like this. To see such beautiful examples of work, and to get critiques from folks who know and pass on what they learned.
I am honoured and do not deserve.
I will get the plug from TOW, and I will use one of us for the work. Soon as I get some cash.
What I have learned from this is amazing.
I thank you all.

[D. Taylor Sapergia]

Before I had a lathe, I used my drill press.  I cut a hole in the base of my bench mouthed drill press to pass a 1 1/8" barrel vertically.  I rotated the table to the vertical position (90 deg. to it's flat position) and clamped the barrel to the table vertically, centering it under the chuck.  Then I drilled the breech end of the barrel with a modified tap drill bit to create a flat shoulder 1/2" into the breech end of the barrel.  So though I didn't have a lathe, I did have bench grinder (my first power tool purchase).

Having drilled the cavity for the plug, I used two taps, both held in the chuck of the drill press and worked by hand, with the belt removed.  The first was a plug tap (bypassed the taper tap) to get the threads mostly cut, and then finished with a bottoming tap with the end ground flat.  This produced good threads right down to the square face of the bottom of the hole.

So, can it be done without a lathe - of course!  But it requires careful thought, pre-planning, and some skill, not to mention courage to go places never before tried.  If you think it through, you should have a successful experience.  Why not try it on a scrap barrel stub first?  I didn't, but I didn't know any better.  Sometimes over-thinking a problem can be an impediment to getting there!

[T*O*F]

I do it exactly like Taylor with some added info.  To center the barrel in the drill press, I select a drill bit the same size as the bore and run it into the barrel all the way.  Then clamp the barrel and tighten everything up.  This ensures that further operations will be in line with the bore.

[RAT]

I have a factory breeched barrel that I wasn't happy with. I showed it to Dan earlier this year, and he offered some suggestions on how to fix it. After this thread I'm thinking of just handing it over to him to fix. He has the tools and the skills. I want to install a different plug anyway... one with a longer tang.

Dan... I'll be at the MHGG fair next weekend, if you're willing.

[bob in the woods]

Re the drill press; mine is a Rockwell free standing floor model , and I do exactly the same . Basically try to use it as a vertical lathe .   If you're careful setting it up , it works just fine.

[RAT]

Question... with the drill press... what are you using to clamp your barrel? Especially a tapered barrel.

[bob in the woods]

I use a mix of c clamps , maple blocks and wedges. Instead of the drill bit run into the bore re lining it up, I have some brass rods that I picked up from the sale bin at Lee Valley Tools a few years back.  They are around 10 to 12 inches long.