Drilling out damascus barrel blanks bought from Dyson, England.

[Rolf]

I bought four pistol blanks. Two for a pair of English duelers and two for a double barrel pistol. I've started on drilling out the duelers.The blanks for the duelers were taken from the breech end of the rifle blank and are 12 in long.  The blanks are as forged. No machining done. The large steel lump at the breech was supposed to be machined into a receiver. 
 



The first step was to turn the breech and muzzle ends between centers. In theory, these sides should be parallel to the forged bore.

 
Next I made two drill guides for each barrel. Each cup is made of 3in of 40mm(1.57in) axel rod. The rod is center drilled all the way through with a 12,5mm drill. Then a 1 inch deep cup is turned at one end with a boring bar and fitted With a set screw . Each cup is turn to fit tightly on one end of one barrel. They are not interchangeable.


The barrel with the cup is then mounted in a drill press in a machine vice and drilled out with a 8 inch long 12,5mm drill from both ends of the barrel. This removes very little material, but gets rid of the worst high spots and establishes a reasonable straight hole through the barrel.


The muzzle cup is then drilled out for the next drill size in a vertical mill, taking care to center the drill. All subsequent drilling of the barrel is done only from the muzzle end of the barrels. These steps are repeated until the bor is reasonably clean. Each hole is started with a 4in long twist drill, followed up with a 8inch long drill and then a short drill silver braised to a drill rod that goes all the way through.
 



So far, I’ve drilled through with 12.5mm, 13mm and 14mm. The first 8in from the muzzle looks clean. There is still some forge scale in the last 4 in from the breech end. This where the lump for the receiver was. I may have to drill 15mm(0.59cal) – 16mm(0.63cal) to get rid of all the scale.

Planning barrel profile.
I want to mill the barrels swamped octagon. Since both barrel is going to be identical, the smallest blank decides the size limit. Estimate were done with this web calculator: https://rechneronline.de/pi/octagon.php
Breech: diameter 28mm (1.10in), Octagon across flats 25,87mm(1.02in), Flat size   9,9mm(0.39in)
Muzzle: diameter 24.3mm(0.9567in), Octagon across flats 22,45mm(0.844in),Flat size 9,3mm(0.32in)

Estimated wall thickness for different Calibers
Caliber 14.5mm(0.57in): Breech   5,7mm (0.225in), Muzzle 3,98mm(0.137in)
Caliber 15.0mm(0.59in): Breech 5,4mm (0.213in), Muzzle 3,73mm(0.127in)
Caliber 16.0mm(0.63in): Breech   4,9mm(0.195in),  Muzzle 3,23mm(0.107in)
Caliber 17.0mm(0.67in): Breech   4,4mm(0.175in),  Muzzle 2,75mm(0.087in)
   
What is safe??
Checking with Rice barrels web site. He has a 12in, caliber 0.62, rifled pistol barrel.
Breech: 25,4mm (1.00in), wall thickness 4,83mm (0.19 in)
Waist 3in from muzzle: 21,0mm(0.827in), wall thickness 2,6mm(0.102in)
Muzzle: 22,2mm (0.874in), wall thickness 2,6mm(0.102in)
It seems reasonable to conclude it should be safe to drill out the barrels up to 16mm. Above 16mm it might be necessary to install a barrel liner.
I’ve made the reamer from an old file and I’m going to start on the reaming bench today. Jerry said he has used blanks from Dyson and they cleaned out as 14,5mm(0.57cal). I want to keep the barrel walls as thick as possible.



What would you regard as a safe wall thickness for a smooth bore pistol barrel, above caliber  0,62?

Best regards
Rolf

[JCKelly]

May I ask, what kind of metal does Dyson use for these forgings?
I promise not to say bad things about it.

[FlintFan]

These are from a cache of old damascus barrel blanks they uncovered a number of years ago.  They are probably over 100 years old.  They would need an analysis to determine what exactly the steel and iron they contain is composed of.

[Rolf]

May I ask, what kind of metal does Dyson use for these forgings?
I promise not to say bad things about it.

These are blanks forged by a belgium barrelmaking firm  between 1800-1850 before they shut down. One of the heirs squrreled away some of the blanks. Dyson bougth them from her heir.
http://www.peterdyson.co.uk/acatalog/ORIGINAL_DAMASCUS_BARRELS.html
I also  bougth a pair of shotgun barrel. Follow this link http://americanlongrifles.org/forum/index.php?topic=40718.0

Best regards
Rolf

[smart dog]

Hi Rolf,
Those blanks are going to be beautiful.  However, are you aware that the vast majority of true English dueling pistols had swamped or tapered octagon barrels?  There were early pistols that used octagon-round barrels (Spanish form) but by 1780 very few were anything but full octagon.  I have a beautiful pair of damascus octagon to round barrels by Hugh Toenjes for use in a pair of early Twigg dueling pistols. But the style will be early in the development of British duelers.

dave 

[Rolf]

However, are you aware that the vast majority of true English dueling pistols had swamped or tapered octagon barrels?  There were early pistols that used octagon-round barrels (Spanish form) but by 1780 very few were anything but full octagon. 
dave

I plan to mill the barrels swamped octagon after the bores are reamed finished. The size of the bore determins how much wall thickness I have to work With, which again limits how much the barrels can be swamped saftely.

Best regards
Rolf

[smart dog]

Hi Rolf,
I apologize.  I did not see your sentence about making them octagon in the original post.  They should be spectacular barrels. I think you should be OK with wall thickness particularly since pistols usually are not charged with heavy loads.  My only concern is that they are not modern steel and likely have strong and weak spots from the welding so it might be wise to figure the best way to maximize the wall thicknesses at the breech with the smallest caliber you can achieve.  I don't think thickness at the muzzle is very critical, only the breech and perhaps about the first half of the barrel. Most duelers that I handled did not have steep swamps and were almost just a slight taper with at most a slight flare at the muzzle. They one exception was a pair of Wogdons from the 1780s. Those had a very noticeable swamp and flare.

dave

[Curtis]

Very exciting project, Rolf!  I am looking forward to seeing the finished barrels!

Curtis

[T*O*F]

I notice in the pics of the rough barrels that only five flats are evident.  It has been my experience that the bottom 3 flats were not present and instead that area was a continuation of the round part of the barrel.  This simplified the inletting of the barrel, since only a round channel was necessary.  Many of the top English builders did their barrels in this manner.