Requesting input on a cannon build.

[GGaskill]

It looks doable, my biggest concern would be how to mill the extractor slot.

You only need the slot/extractor if you are going to use cartridges. 

[pak40]

Hello friends,

Sorry to use such a familar opening but general statements are getting a little old, and by the response, and free advice I am getting, I think I can consider you all friends.

I finally made it back to the forum.  Work has been dogging me as of late, and I have had little time for anything else.  Supporting the entire navy/marine corp. computer network is becoming a demanding job.

I finally have some general engineering drawings made up of my intended plan for the gun.  They are hand drawn, as the CAD program I downloaded was not all it was promised to be.  The question now is, how do I get them into a format to post here.  I have to drive 30 miles to get to a usable scanner, and I am afraid that my digital camera is going to produce something that will not be presentable.... I guess, when I get the time I will have to give both a try.

I have made little progress for the reason stated above, and also the difficulty in finding stock materials around here.  I try to use bits and pieces from the scrap yard, but for some things (trunions, block, and breach) I am looking for pristine steel of known qualities. 

Another project I will be embroiled in soon that relates to this project is the building of a large turning tool.  Its become apparent to me that my little smithy is not going to cover all my needs, and I am going to have to turn the barrel in a number of places.  The barrel has a mounting ring on it that is going to make it impossible to slip the tight fitting trunnion section over.  It also has a raise section at the front of the barrel with flats that will have to be removed for the same purpose. The breach will have to be turned uniform from the end to a point at least 6" up so that the breach extention can be installed.  This is all before I even try to start building.....    I don't intend to farm much if any of my work out, so this is the only way i am going to "git er done." Basically it is going to be a rudimentary low speed lathe capable of holding the large piece, and holding a cutting tool to the outside, as well and working on the bore of the piece.  I already have an idea in mind, but at this point the major hold up is again, materials.  As with all my projects though, with enough patience an opportunity usually presents itself.

I really appreciate the pics that were posted, they are better than the ones I have found so far and help me to better understand the workings of the design I am working on.   on some of the other posting though it was mentioned that the block is tapered.  While in the original design it is, on mine it more than likely will not be.  There will be a stepped portion at the end of the breach section for the block to stop at.  Some may be concerned about the possibility of gas leaks at this point, but I intend to make the union of the block to the breach fit so closely that this should be eliminated, if not, the installation of a couble rubber O ring round the barrel will so that it is compressed by the block should take care of any leakage.  I have no desire to make a part of my gun tool kit a hammer to knock the block loose.

I am still carefully considering my options for cartridge vs. loose ammunition, and shot construction.   Theoretically, if I use a cartridge similar to that used in the original hotchkiss, fired by a shotgun primer, shotgun shell, or some other non-contained ignition source I should be "ok" with the BATFE, and I certainly have the experience at this point to turn out shell hulls of brass of this size.  To get around the extraction issue, should I choose to, is a pretty simple matter.  Since I will not be too concerned with speed of loading (no battles to be fought), a long shaft of hardwood with a soft metal tip could be fabricated and used as a rammer once the breach is opened, thus eliminating the need for an extractor.  As for shot, I see that was a big concern to several.  When I first started I was "spitballing."  More or less just throwing an amalgum of ideas together that I thought would make this device go bang in a safe way.  And while a round ball would work, it would not be particularly effective as pointed out.  Thats why I am going to get some aluminum and cut a mold for solid lead bullets.  As pointed out, the enlongated bullet would be an easier choice anyway.

I am also considering a change in the design of the breach locking system.  I think it might be better not to leave so much of the internal block hollow, and have it latch on both sides of the breach opening.  At this point I am considering a smaller crossbolt that actuates cam levers that lock into the breach extention at the rear thereby reducing the amount of metal to be removed from the breach block, whichwould in tur allow more room for a firing mechanism to be self contained in the block.

Hopefully at next posting I will be able to put some of my design drawings out here for you all to see.  They are nothing spectacular, but it would be nice to show you all what the marbles rolling around in my head look like (ha ha).

Thanks again for all the input.

[GGaskill]

pak40--Check your PM.

[Victor3]

If you make the breech block fit with only a small amount of clearance with no taper it's going to stick after a bit of fouling, O-ring or not.

I'd suggest keeping the taper as part of the design (Or keep a hammer handy). It's important to the function.

[pak40]

I haven't fallen off the earth or exploded myself still, I've just been very busy again.  I finally had more time to devote to cannon work.  I have stopped work on the barrel/breach for now (physical work anyway).  I have been concentrating on the construction of a carriage for it.  I think your comment is very astute victor3, and you are probably right about the sticking, however I am still considering other options. I had originally anticipated using a black powder substitute and made the assumption that it would burn cleaner, but after taking out my blackpowder arms last weekend I know now that this is not going to be the case.... the pyrodex I was using gummed up my colt almost to the point of inoperability after only about 35 shots.  If I do go with tight clearances, and a straight block body, I am going to have to use bearings of some variety, or swamp the sides of the block so that contact with the receiver is only in the critical areas for lock up.

So far as the carriage goes, I have an axle, steel wheels, and a whole lot of 4 X 6 planks, which I am fashioning into a "Y" frame.  I will likely get some cold rolled steel for strapping and extra strength where the trunion meets the carriage and other critical points. As I have read, the original hotchkiss was made all of metal, but I suspect wood will work just as well, and in this case probably better, as in some of the articles I have read on these guns, some have the nasty tendency to flip on firing.  With the extra weight of the wood, I would imagine that this effect will be better controlled.  I still have not decided on what type of mechanism I will use for elevation, but I am leaning heavily toward the original, which is a screw through a crossbar in the carriage, however, I did see a neat  pic of the larger version wherein they used a sort of "tongue" under the breach, with a crank handle to actuate it.

Another thing that has piqued my interest is the use of cartridges, after pouring over the ATF regulations I have come to the conclusion that I would be ok in making a cartridge with no provision for a self-contained primer but rather just an orofice for the flash of priming to run through. I have come up with some ideas on how to do this, but I am going to call my local atf and make absolutly sure I am right before persuing this.

That pretty much brings you guys up to speed on where I am right now.
Sorry its taken me so long to get back.

[GGaskill]

You are probably right about the cartridge situation but I suggest you get an ATF letter approving the idea before building it as insurance against an ambitious agent.

[Double D]

Another thing that has piqued my interest is the use of cartridges, after pouring over the ATF regulations I have come to the conclusion that I would be ok in making a cartridge with no provision for a self-contained primer but rather just an orofice for the flash of priming to run through. I have come up with some ideas on how to do this, but I am going to call my local atf and make absolutly sure I am right before persuing this.

Do not rely on any phone call as the legal basis for using those cartridges. Write a letter to ATF in Washington and get a written response stating you idea is legal. And then after you have the letter saying it's legal, then and only then make the cartridges.

 

[Powder keg]

You need to get ahold od the "Firearms technology" branch of the ATF. I'll see if I can find there address.

Wes