doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com monoblock vs chopper lump const....better?

The late British gun guru (and engineer) Gough Thomas thought highly of "fretted" barrels. From his "Gun Book":

"With resleeving now thoroughly established, it seems remarkable that no British firm has adopted the fretted barrel, with its possibilities for combining greater strength with a reduction in the cost of producing double guns." He continues the subject for a long paragraph.

Manufrance also used fretted barrels, going back quite some time. Most of their "Robust" guns have the very visible "step" between the monobloc and the tubes. In fact, at least in the States, if you see a gun with that "step", I'd say there's at least a 90% chance that it's a Robust.

The pictures of Henri Pieper's patent of his method of joining bbls is his US patent. Said patent was issued Aug 23, 1881 as US patent #246,195. This patent can be viewed here;
http://www.pat2pdf.org/patents/pat246195.pdf
A reading of this patent quite well describes the method of joining. The breech piece & bbls were stated to be turned with mating conical tapers & were further joined by either brazing or soldering. There were no threads in this patent. This did give the "Fretted" assembly.

Miller,

I do enjoy our exchanges. Reminds me of many years ago on the board. The back and forth about patents vs seen examples.

I have been exchanging emails with an international patent attorney based in Europe. He has helped educate me a bit. Seems there were different standards that various countries used regarding intellectual property. In Belgium, "patents by work" and "trade marks by first use in commerce" were the norm. While in the US, changes in method required a new patent to be filed to amend previous patents, this was apparently not the case in Belgium. I don't even pretend to understand all this. If there is a patent attorney reading this, HELP!

It all started when I mentioned the "Paris Convention for the Protection of Industrial Property of 1883".

Gil, thanks.

Buzz, most of what we see today came about by trying to invent the "better mouse trap". Do a search on Google patents for "mouse trap", you will be amazed....

Any how, that is why I put together that patent compendium, as Daryl calls it, for US patents. I am working on a similar one for British patents. Any one care to work on a French or German patent compendium?
http://damascus-barrels.com/uspatentnom.html

Wild Skies,

Here is an excellent site for such things.
http://www.hallowellco.com/abbrevia.htm
Be sure to check out the photos for each definition.

Pete

Pete

I've never seen any posting or firsthand account of where any of these various designs failed where a different design would have held together.

Chuck H, I had a Wm. Powell & Son .410 back-action hammergun built in 1886 with drop in lumps that failed...I doubt very much that would have happened had they been chopper lump.

Thank you PeteM for posting that link confirming that chopper lump and Demi-bloc construction are different terminologies for the same thing.

Wild Skies, can you describe the failure ? Was it a converted rifle ? Pretty early for a 410.

The Browning Superposed was originally made with monoblock construction. After the first 1200-1500 guns FN changed to the later style in about 1932. I am unaware of any history on the reason for the change, but the speculation is that it may have been to allow guns to be built more quickly. I believe the monobloc guns have functioned well.

Contrary to what Hallowell says, the demi-bloc (as originally defined by Pieper) is not the same thing as chopper lump. The demi-bloc is a special case of chopper lump - it is a chopper lump in which the two lumps are joined by use of a dovetail. NOTE: That is not the same thing as dovetailed lumps, in which the lumps are attached to the barrels by use of dovetails.

McIntosh discussed the difference between chopper lumps and demi-bloc in his discussion of the Winchester 21 in "Best Guns".

I used to own (wish I still did!) a pretty little Pieper demi-block 28 ga hammer gun. Upon close examination, it did in fact have chopper lumps, and the lumps were joined to each other by a vertical dovetail. The dovetail joint was almost invisible, but I was able to find it with some difficulty.

Jim Cassada, aka Seamus O'Caiside

Pete;
Thanks for posting page two of the 1881 patent. As I have no reference to an earlier one I am taking this as his original patent. From both the illustrations & the description it is obvious this patent did not describe the bbls being threaded in. As to whether this patent was sufficient to protect against a gun being fitted with a one piece breechpiece with bbls joined by some other method in Blgium I do not know.
I do not believe it would have done so in the US. Note that D M Lefever was issued patent #205,193 on June 25, 1878 for a Doll's Head rib extension having a sq shoulder rather than the normal curved cone. Some time later Remington Arms began using a sq shouldered doll's Head on their doubles. Lefever sued for infringment & lost the case. The basis of his loss was that he had written the patent stating the mating surfaces of the Doll's Head & the recess in the breech were cut on the Arc of a Circle having the hinge as center. Remington won on the fact they had cut their shoulder on a straight line being tangent to the circle rather than a part of it. Lefever argued that the Sq Shoulders were the basis of the patent, not whether it was cut on a arc or straight, but Rem prevailed.