Howitzer Powder Chamber Questions

[PATM]

Hi to All,

I have a couple of Newbie questions...........

What would be appropriate dimensions (not scale dimensions )of a powder chamber for a 3/4  Mt. Howitzer barrel with a 2.67 soda can bore....  ? dia x ? length.

What would be the maximum amount of powder charge in ounces, that could be put in that recommended sized powder chamber.

Considering the reduction tapering of the bore from 2.67 down to the powder chamber dia., I assume that the projectile will not seat against the powder charge.....right?

Thanks,

PatM

 

[Zulu]

Hi PATM,
Good thing you asked.   The 2.67 bore is not tapered.  It is 2.67 all the way down the bore, then necks down to the powder chamber.  The projectile sits against the powder chamber.  Someone else here will clarify your other questions. 
Too many people don't ask questions till their gun is finished.
Zulu

[Zulu]

PATM,
As an adder, not seating any projectile right against the powder charge could have disasterous results.
Zulu

[PATM]

Zulu,

The full scale 1835 Mt. Howitzer plans I have (A. Mordecai), show the  barrel with a 4.62 bore necked down to a 3.34 powder chamber at the breech. I don't see how the 4.62 projectile would ever be able to be pressed far enough into the breech to be seated against the charge.

What am I missing?

Thanks,

PatM

[Double D]

Why not scale dimensions?  That's how you come up with the dimensions for chamber.  In a previous post, you mentioned you have a plan from  Mordacai. You  can get every single measurement from that drawing for your cannon.  If you can do Excel you can simply measure the drawing and make a spread sheet and upscale all the measurements in about 10 minutes

The diameter of the powder chamber should be 2/3rd of bore diameter.  

In a previous post I provided you with a link where you can compute your powder charge.  Here is the at link again.  Safe Loads and Construction

As to the taper from bore to chamber, again that can be scaled from your drawing.  You can measure the length of the taper in your drawing, do the trig to get the angle.    Mordacai says the ammunition for the howitzers is fixed.  The charge and ball are attached to a tapered sabot.

[Double D]

I did a real quick Excel spreadsheet with just the three measurements you gave and got the diameter of the powder chamber.

Diameters   original   three quarter   multiplier

Bore           4.62           2.67                   0.577922078

chamber   3.34           1.93

[armorer77]

In my half scale Mt. Howitzer the barrel dia. around the chamber is only 3" for a max powder chamber of 1"

[Zulu]

Zulu,

The full scale 1835 Mt. Howitzer plans I have (A. Mordecai), show the  barrel with a 4.62 bore necked down to a 3.34 powder chamber at the breech. I don't see how the 4.62 projectile would ever be able to be pressed far enough into the breech to be seated against the charge.

What am I missing?

Thanks,

PatM

PATM,
The projectile would seat up against the powder chamber.
Zulu

[dominick]

I use an 1-1/4" diameter powder chamber for a soda can Howitzer.  Not sure of the length but I think it's 1-1/2".  I make the breech plug face square with a slight taper at the chamber opening and use a loading tube.  This places the projectile against the charge and minimizes the air gap if using a can.

[GGaskill]

The charge and ball are attached to a tapered sabot.

The tapered sabot is why there is a long tapered section to the chamber.  If you aren't going to make up your loads with that sabot, you don't need the long taper.  I do mine with a 1" drill for the chamber and a 1.719" drill for the bore (1/2 scale, golf ball bore.)  For a 3/4 scale, I would go with a 1.5" chamber and a soda can bore with the chamber just a continuation of the bore at a smaller diameter (actually, I would drill to the bottom of the chamber depth with the 1.5" drill, then drill to the bottom of the bore with the 2.625" drill or the largest drill I had and a boring bar for the rest.)  The shot would be sitting right in front of the powder charge unless it were a much reduced charge.