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Discussion Starter · #1 ·
This model is to be functional. 40-50% scale was desired for physical size and capacities of my machinery. 42% was chosen because that scale makes many of the major parts fit in readily available material sizes. 410 is not so far off the nearly 5/8" diam of a 42% 37mm cartridge as to be awfull looking. 20 ga would be just about right on but would cost more to shoot. In either case pressures are low enough to deal with easily. Some of the rifled slug deer hunters have been getting interesting results out of 410 slugs in rifled barrels.
 

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Discussion Starter · #2 ·
Re: continued response to quiry(s) 'bout 410 choice

Recoil was managed so well by the weight of the cannon and carriage structure in the orig Hotchkiss that the historical articles claim that it would remain laid on target from shot to shot. I wasn't too confident that this model with a lot of 6061 T6 and 7075 T6 alum substituted for the cast iron and bronze of the orig would do the same if I were to use 20 ga rifled slugs -- and procuring 41 cal rifled barrel blanks is easier than would be 20 ga rifled, particularly w/sufficient wall thickness for this application.
 

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Re: continued response to quiry(s) 'bout 410 choice

The project is a very interesting one both from the design standpoint and machining and tuning.
It is sort of unusual --- for instance, technically it falls outside the rules of this GrayBeard topic group because it employs a centerfire smokeless cartridge. But I felt that this group would find it interesting and would most likely have questions and comments from which I could learn a great deal.
Thanks Guys !
 

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HAGER Welcome , are you proposing to shoot shotgun slugs from cannon ?

If so lots O flak coming your way , have you met our moderator? :eek:

DD will be along shortly to blow your idea up

We dont do smokless on this forum .

Sounds like a cool idea though !

Please dont let ANYTHING ANYONE SAYS TO RUN YOU OFF!

You may have talk about more conventional stuff .

You might change your plan to shoot heavy duty proprietary brass casings heavy duty for lots of reloads using black powder , maybe even with a small baggie with powder inside.

The type you just put together on the spot no crimp.

I dont think machining a dozen or two ,using 209 shotgun primers would be too hard.

Good luck and welcome, you have alot of ambition so sick around and learn.

Gary
 

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Sweet ,well there you go 8) !
I stand corrected, cant wait to see some video of this thing chugging
thru a box of 20ga. ;D

Gary
 

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??? Do or DO NOT?, carbineone 1964?
 

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for your ammo, using either .410 or 20 ga., you could get a Mec Jr. shotshell reloader, used for around$50.00-$100.00, look up old shotgun blackpowder loads and load your own slugs quite easily. I have reloaded 12 ga. 20 ga. 28 ga. & .410 shotshells since the mid 90's and saved a lot of money. I would think the only semi-hard part might be finding the slugs.
 

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Discussion Starter · #12 ·
The design copied for this model is the 1874 Hotchkiss.


Although I'll be testing with modern rifled slug amo, I had sorta figured that when doing handloads for the thing they'd be in BP or Pyrodex. I'd really like to use brass cases but if I do so I'll have to mod them to take norm shot shell primers for the current design. Reason for that is that the exractor is designed like the orig Hotchkiss, with no sort of spring retention of the rim in the ectractor hooks. The geometry of the 410's rim is such that it is easily pulled from the chamber but as it moves rearwards gravity makes the rear drop out of the hooks prematurely. That seems to be the case because of the different center of mass of the case due to the plastic portion ---- so this may not be a problem with all brass cases ---- but for the moment it is. My solution is TOTALLY out of period for the cannon but works wonderfully. I mounted a tiny rare earth mag in the extracter face which sticks the steel cup part of the normal shot shell primer up in the extractor hooks long enough to get the case mouth clear so it can drop out the bottom of the receiver.
 

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Discussion Starter · #13 ·
also I was aware of the 50 cal limitation thing and that was part of the orig reason for choice of 410. I have often wondered though, about the incongruity of that regulation and the use of 20 ga and 12 ga slugs in rifled barrels which is quite common these days.
 

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hagar said:
also I was aware of the 50 cal limitation thing and that was part of the orig reason for choice of 410. I have often wondered though, about the incongruity of that regulation and the use of 20 ga and 12 ga slugs in rifled barrels which is quite common these days.
Shotguns (the "proper" ones anyway) have a 'sporting' exception as-do things like elephant rifles in .700 Nitro. The trouble with something like a Hotchkiss in 12ga is convincing somebody it is 'sporting' and not, say, an enlarged Street Sweeper (which is officially 'not-sporting'). Doable, but a bit of a can of worms.
 

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Discussion Starter · #15 ·
I've been told there is in addition to the "sporting" a label which is, "antique and curio" - or some such verbage. I havn't taken time to research that yet but suspect that it has to do with the Manufacturers licence classification under FFL.
 

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hagar said:
I've been told there is in addition to the "sporting" a label which is, "antique and curio" - or some such verbage. I havn't taken time to research that yet but suspect that it has to do with the Manufacturers licence classification under FFL.
The 'Antique' exception to Destructive Device is what most cannon here over .50 cal have. That requires 'antique ignition'-- flint, fuse, quill, etc for anything modern-made.

C&R (Curio and Relic) is a separate ball of wax requiring guns to be old and/or on the ATFs list and also isn't a blanket exception. C&R guns can still be NFA items with all that entails.
 

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While doing research on this subject last night I came across this From the ATF National firearms act Handbook dated April 2009. https://www.atf.gov/file/58251/download.

I excerpted two passages from chapter 2 "What are Firearms under the NFA" that are relevant to this discussion.

https://www.atf.gov/file/58196/download

2.1.8.2 Large caliber weapons.
The second section of the definition states that any type of weapon by whatever name known which will, or which may be readily converted to, expel a projectile by the action of an explosive or other propellant, the barrel or barrels of which have a bore diameter of more than one-half inch in diameter is a destructive device.
This portion of the definition specifically excludes a shotgun or shot gun shell which the Attorney General finds is generally recognized as particularly suitable for sporting purposes. ATF has issued rulings classifying specific shotguns as destructive devices because they have a bore of more than one half inch in diameter and were found to not be particularly suitable for sporting purposes.
Section 2.2 Antique firearm.
Firearms defined by the NFA as “antique firearms” are not subject to any controls under the NFA.22

The NFA defines antique firearms based on their date of manufacture and the type of ignition system used to fire a projectile. Any firearm manufactured in or before 1898 that is not designed or redesigned for using rimfire or conventional center fire ignition with fixed ammunition is an antique firearm. Additionally, any firearm using a matchlock, flintlock, percussion cap or similar type ignition system, irrespective of the actual date of manufacture of the firearm, is also an antique firearm.

NFA firearms using fixed ammunition are antique firearms only if the weapon was actually manufactured in or before 1898 and the ammunition for the firearm is no longer manufactured in the United States and is not readily available in the ordinary channels of commercial trade. To qualify as an antique firearm, a fixed cartridge firing NFA weapon must meet both the age and ammunition availability standards of the definition.

Concerning ammunition availability, it is important to note that a specific type of fixed ammunition that has been out of production for many years may again
become available due to increasing interest inolder firearms. Therefore, the classification of a specific NFA firearm as an antique can change if ammunition for the weapon becomes readily available in the ordinary channels of commercial trade.
For questions or interpretations contact ATF direct.
 
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