Brass cases for signal cannons....

[Third_Rail]

I want to make a custom size signal cannon, and I wonder - what thickness and type of brass should I use for the cases?

I want to make a 4 gauge or larger, but I don't want to be buying the cases from Cannon-Mania or somewhere else if I can safely make them myself. Also, I'd be making a shorter version (think 4 gauge and 2" long overall instead of 4.5" overall, a 4ga short, if you will)

(text referring to design of DD removed by CW)

As to the signal cannon, it'll be 1144SP.

(text referring to design of DD removed by CW)

Thanks in advance, all.

[Cat Whisperer]

Third_Rail -

Great Topic!!  We've not discussed much at all the construction of cartridges for signal cannons.  

My apologies for editing you post.  It is our intent to limit the scope of this forum - hence my editing your questions regarding similar functions of the above as a registered legal DD.  Please don't hesitate to pursue that course, it's clear your intent is to stay within the scope of the law, and we wholeheartedly support that.

Back to the original idea -

Cartrige brass is a specific formulation.  The issues of strength and resistance to work-hardening are key.  

As you well know, shotgun shells need very little strength - the brass on the bases of the plastic shells was ADDED because the ALL-PLASTIC ones wouldn't sell!  It is merely cosmetic.

So too, look at the flare pistols - 25, 26.5, 37mm have ALUMINUM (to be fired once) cases.

[Third_Rail]

Well, I think I'd be dealing with significantly higher pressures... but I may just go with naval brass or something similar if I can't get cartridge brass.

Since I'll be making the whole thing (barrel, cases, etc.) myself, I  can make up the dimensions as I go.

I'll most likely pursue what you suggest - looking at 20mm, 40mm cases and go from there.... double that thickness would be a good starting point in my mind. I'll have to do more research on this.

[guardsgunner]

Because the size was convenient, our  !.5" breechloader uses copper cartridges. They work well. We are firing a 1.5 lb.projectile/3oz.charge.

What is going to cause High pressure's in a signal gun?

[Cat Whisperer]

 ....  What is going to cause High pressure's in a signal gun?

The high pressure here is to use a cartridge to fire a large projectile.

Because (speaking of the top of my head, not quoting) when firing a cartridge loaded projectile of greater than .50 caliber the device becomes a "firearm" (legal term) that must be registered as a DD (Destructive Device) through BATF.  

We have chosen, on this forum, to not include the discussions of such here. Several of our participants have such legally registered devices and we fully support the safe, legal use of such, but the discussion of such is not within the scope of this forum.

And, the choice of going to a standard )or modified standard) cannon cartridge (which are readily available through several surplus vendors.

I think the added strength that you see in these is for the integrity of the round in handling and extraction - the strength is not needed to withstand the pressure inside during firing - execpt perhaps to keep the brass from being extruded into the corners at the base.

[guardsgunner]

Sorry, I did not understand that his signal gun was going to fire a projectile causing the pressure.
  As for our gun, It' is a direct copy of an 1856 design. Not internaly primed.

[Cat Whisperer]

Because the size was convenient, our !.5" breechloader uses copper cartridges. They work well. We are firing a 1.5 lb.projectile/3oz.charge.

and ....    As for our gun, It' is a direct copy of an 1856 design. Not internaly primed.

Very interesting point.  'Cartridge' loading, yet externally primed.  A fine point of law worth defining; and a very interesting point in the development of shootin' irons.  I would ASSUME (classic definition) that the law would be referring to 'modern' internally primed cartridges; key word: ASSUME.

[Third_Rail]

Reason I ask about thickness is twofold... one, so the brass doesn't flow or rupture, and two, so I can reuse it many, many times.

I won't be resizing the cases each firing, so I need them to be fairly resistant to size change (and with a straight walled case I think that should be easy to do)

[GGaskill]

You need to keep the case walls thin enough in the neck to allow the neck to expand and seal the breech.

Cartridge brass is 70% Cu and 30% Zn.  Like most brasses, it work hardens so you need to anneal the cases after you're finished machining them or you will get splits.  Depending on how much you machine them, you may need to do some intermediate anneals also.

Also expect them to be expensive even if you make them.

[Cat Whisperer]

Reason I ask about thickness is twofold... one, so the brass doesn't flow or rupture, and two, so I can reuse it many, many times.

I won't be resizing the cases each firing, so I need them to be fairly resistant to size change (and with a straight walled case I think that should be easy to do)

Look closely at how you minimize head-space.  You need some room for variation in size and accumulation of crud, but with a minimum of head space the case will stretch much less.  Agree, straight-walled cases last a long long time (referring to .30 car, .44's, 38/357's, .444's, .45colts, 45-70 and .458WM's.  ( I shoot many .458's full-house loads and seldom resize (Ruger #1).

[Third_Rail]

Hm, I'll have to really do some research (and experimentation!) on the thickness of what I need. Maybe a short (.5") section near the neck much thinner, with the rest thicker? Who knows at this point...


Well, brass is going to be quite a bit no matter what, but since it'll not be too much more expensive I might as well be able to have something that I can say "Look! I made this." with, you know?

[GGaskill]

http://www.anchorbronze.com/c26000.htm" target=_blank">Here is a properties page for 70/30 (C26000) cartridge brass.  Your local metals dealer may not stock it.  And since most cartridge cases are drawn from flat stock, it may not be available in round stock.

How about describing (or giving a link to) the design of the cartridge.

[Third_Rail]

How about describing (or giving a link to) the design of the cartridge.

think 4 gauge and 2" long overall instead of 4.5" overall, a 4ga short, if you will

 :grin:


Basically, a 4 gauge with a thick rim, about 1/8" thick and coming out as far from the case. I want plenty for an extractor to grab without damage.

[jeeper1]

What is the diameter of a 4 gauge?

[Third_Rail]

.935", but I'll be using 1" for it. 4 ga. is just the general size.  :-)

[jeeper1]

Have you looked at or considered the aluminum cases for the 26.5 mm flare guns? With a little work the can be made reloadable, I've done it.

[jeeper1]

Forgot to say, they are one inch in diameter. Loaded flares or smoke rounds are sold by Dan's Ammo.

[Third_Rail]

I actually have an HK flare gun in that caliber. I'll be picking up some flares for the 4th of July, so we'll see if those are the size I want or if I really will just turn my own.

[jeeper1]

Get plenty, they are a lot of fun if you don't shoot any red flares (those tend to attract unwanted attention). To reload, just pop out the fired primers and drill for shotgun primers.

[Third_Rail]

White should be plenty fun for me.  :grin: