doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Monoblock - why machine barrels separately?

There was French company Monoblock and at Intl. Gun Show in Paris in 1900 this company show double barrels made from one piece of metal. Author of this article noted, that these barrels been known since 1880.

I don't understand where the extra weight would come from? A modern multi-axis machine can contour a solid billet to match the external appearance of a conventional double. And running a machine for a production run is cheap compared to extensive handfitting.



I thought the whole reason for regulating doubles was because the barrels were two separate units? I would think that precision machining both bores in near perfect alignment relative to each other would allow a simple CAD operation to determine the appropriate angle each needs to be for a given convergence point?

Please keep in mind my ignorance when it comes to double guns (not machining--much experience there) so be gentle! I have no idea how double gun barrels are joined so I'm guessing when some of you refer to weight that there must be hollow sections under the ribs and between the barrels?

Thanks to all of you for participating and taking time to answer the crazy questions of a novice!

Solid, Solid[ One-piece double barrels] are not a new inovation!In 1870 the Joseph Whitworth Company, the foremost U.K. mechanic of the day, was issued a patent covering one-piece barrels!Examples of these barrels sometimes surface on guns made in the U.K. A fine example of these barrels was found on a 12G hammer double, by Ingram.This gun was covered in series of articles in the Shooting Times, circa 1986, by the late Geoffrey Boothroyd. Investigations carried out included X-Ray examination that clearly shows the one-piece construction.
So far as Mr Lippard,s work is concerned, despite being an excellent example of C.N.C machining, I could see no evidence in the process patent [not a design patent] that was not pre existing & established Tool design/manufacturing technology.

Yes, there is a considerable amount of "Air Space" between the bbls & under the ribs on a conventional bbl set. I too worked for 35yrs as a machinist & put in quite a bit of time on CNC Milling Machines. Thet are marvelous machines, but all machines have their limits. Bores would have to be put in on precise angles & even the best of gun drills will veer a little sometimes from a perfectly straight line (I have been exposed to them also). Conventional bbl machining is also much different from what it was in the late 1800's. I don't know how many makers are using it but the "Roto-Forge" method of making bbls Ithaca began using in the early 80's could spit a perfectly straigt, round & concentric bbl out in seconds, starting with a blank tube about 12" long as I recall which wasted no metal at all. Tubes produced by such a method & combined with a CNC machined Mono-Block would be vastly more economical than machine the entire bbl, "+" it allows a different mat'l to be used for the lug area giving a different heat treat from the bbls, another consideration of some importance.
There are simply a lot of factors to be considered, no doubt the companies which build them have considered most of them.

At the Las Vegas show several years ago, I tested one sample of Lippard's gun with one-piece barrels and found them to be of typical weight, balance, and MOI. I did not test them for regulation.

I'd surmise thw main factors on current level of acceptance. One, they are still costly relative to current maker's product cost. And, two, makers and their customers still have a lot of inertia in the direction of current current barrel assembly practice. I'm sure one-piece barrels will come, I'm just not sure when.

No one has mentioned yet that one-piece barrels appear very limited in repairability. Of course, if they become cheap enough, that would be a mote point.

Miller,
When Builder and I visited Galazan's facility a few yrs back, he showed us at least one maybe more roto forge barrel machines. None were up and running at the time, but it looked like he'd acquired them secondhand. Maybe Ithaca?

Chuck;
I recall in the late 70's early 80's Ithaca was advertizing these bbls big time. They stated how the cold forming process incressed the strength & hardness, producing a "Vastly Superior" bbl but the machinery was "Extremely Expensive", but they were "Willing" to utilize it to bring the customer the best possible product.
Then in about 1981 I read an article (By Ithaca) in one of the machining Trade Mags where different corporations wrote up how different processes had affected them. In this "Rag" they explained how the process had allowed them to drop the grade of steel used from 4140 as I recall to something on the order of 1030-1130 & the process resulted in the final product having essentially the "SAME Strength" as their previous bbls had. They further stated that with the savings in both mat'l & labor they expected to completely amortize the new equipment in approx 3 years. Beyond that time savings would be tremoundous.