Advice please

[Derek Rose]

Just starting a Harpers Ferry flintlock pistol,plenty engineering experience, but never made a gun before, can anyone offer advice?
1, I have a .500 ball mould, so plan to use this size bore...what is the clearance, ie;what do I ream the barrel to?(to be correct the cal. should be .53)
2, Is bdms good enough for the barrel or should I use something better?
3, How smooth should it be inside...is a reamed finish good enough?

 

[Zonie]

.520-.530 would do fine with a .500 diameter ball and a .015-.018 thick patch.

As I recall, a reamer should produce a 32 microinch finish which would also be fine.

Actually the reamer will produce a better finish than some of the other smoothbores being made in Spain.

I'm not sure what "bdms" is. Perhaps I would have a better idea concerning its suitability for a barrel if I knew what it was.

If it is "DOM" Tubing (Drawn Over Mandrel) then my answer is, "No. DOM tubing is production seam welded tubing that has been drawn over a mandrel to smooth out and cover the weld.
DOM Tubing, even in its heaviest guages was never intended to take the sudden increase in pressure that a gun barrel must withstand."

 

[Derek Rose]

Sorry...bdms- bright drawn mild steel

 

[shortstring]

Sorry...bdms- bright drawn mild steel

Now days there's 2 schools of thought as far as barrel steel. A lot of barrels are still being made out of 12L14. It was the steel of choice for the last 50 or 75 years as Bill Large, Getz & others used it for making round ball barrels.

Also there's a trend toward using 1137, 4140 or possibly 4150 prehard. Ed Rayl & Jim McLemore are a couple of barrel makers who have switched over to these barrel steels. Mostly safty & liability issues brought about the use of these stronger steels.

If this barrel you're making is to be rifled I personally would size it around .510. Make you up a square, hickory backed reamer, I just use shim stock to deepen the cut. A common machine reamer may or may not give you a good enough finish. Although you could finish the hole with emery cloth. Just cut a length ways slit in a wood dowel that the cloth will tightly slip into. Then wrap the emery around the dowel til it snugly fits in the barrel. Spin it in a drill motor to polish the bore. Yes a twist drill will drill this hole. I'm assuming that this tube will only be a foot long or so. If you know of a cutter grinding shop with an Oliver drill grinder have them grind a self centering point for you as it will drill straighter than a common drill point grind.

Paul

 

[Derek Rose]

Thanks for that, Hickory backed reamer? please explain, thats a new one on me
Derek

 

[shortstring]

The wood back reamer or long bit or is a square piece of steel 6 to 8" long backed by a piece of half round hickory. The ones I make are made of high speed steel which involves some machining to accomplish. I've heard of people making them out of cold rolled steel & soldering a hard cutting surface on to it. Say a high speed steel hack saw blade. The way they work is the square fits into the hole in such a manner so the corners of it scrape metal slowly. You then add to a shim that's in between the steel & the wood to deepen the cut & continue. Slow is the key word. Some where around here you should be able to find a picture of one. Ned Roberts or Walter Cline's book would have one. They use them in the old video The Gunsmith Of Williamsburg.

 

[Derek Rose]

OK, got the concept...how do you hold the steel to the wood?

 

[shortstring]

Basically you just design the steel so that the wood can't slide off the end. Some steel sticking down at each end of the wood. Of course after it's in the bore it holds it self together. Ream from the breech end. As far as the muzzle end I never run the reamer completely out. It will emerge until I can just feel it no longer cutting, I then head back to the breech. This will make sense the first time you do it. The problem is that it will bell the muzzle if you take it all the way out. There's a good chance that the breech will be belled but it doesn't matter if it's below the ball.

 

[Derek Rose]

I get it....Ill try out on a piece of scrap first.
Thanks

 

[ohio ramrod]

The "drill doctor" drill grinders do a good job of grinding a split point as well. I was a tool grinder for over twenty years in thee different shops and while the drill doctor doesn't do as good of a job as a windslow they don't cost over 200 grand either.I got a drill doctor when I retired and use it on all of my drills.

 

[flintriflesmith]

OK, got the concept...how do you hold the steel to the wood?

The wood and paper shims can be held to the square bit with a couple of leather washers. Remove the front one before the bit enters the barrel and put it back on as the bit emerges from the muzzle.

There are pictures of square bits in this article on my web site.
http://www.flintriflesmith.com/ToolsandTechniques/barrel_making.htm

Gary

 

[Derek Rose]

Thanks for that gary....My barrel will only be 10" but im intrigued now, How do you bore say a 32"barrel? More importantly , how did our forebears do this? I try to work as traditional as possible.
Derek

 

[flintriflesmith]

Thanks for that gary....My barrel will only be 10" but im intrigued now, How do you bore say a 32"barrel? More importantly , how did our forebears do this? I try to work as traditional as possible.
Derek

If by "bore" you actually mean "drill from solid stock" the answer is they didn't until the deep hole drill was developed in the 19th century. That is why tubes were welded (either with a straight seam as I show on my web site or spiral seam--so called twist weld) and most cannon were core castings.
Gary