Aluminum Thoughts

[phsarge]

OK I have seen discussion on use of aluminum for cannon balls. My question is what is the thought of using it for Mortar Shot? I have access to alot already melted so there is no cost for me was just courious if anyone has done this in there mortars or what the thoughts are on it.
 
Jeff
PHsarge

[ironball]

No reason why it wouldn't work, other than the melting point is way beyond the capacity of the average home caster.

[Cat Whisperer]

Solid aluminum gives you the weight of the typical mortar hollow iron powder-filled shot.

Folks that shoot in competion (N-SSA) will tell you that if they are 'dinged' from hitting another that they will no longer fly straight.

Use a mould made of metal - it cools from the outside in; where a sand casting doesn't and won't give you the 'roundness' needed.  Turning on a lathe will give you the best dimensions.

[Artilleryman]

I have tried aluminum projectiles in a 12 pdr mortar.  Wind drift is a big problem, and small variations in powder charges produce large differences in range.

[Cat Whisperer]

I have tried aluminum projectiles in a 12 pdr mortar.  Wind drift is a big problem, and small variations in powder charges produce large differences in range.

Do you recommend solid iron?

[phsarge]

What I had read was they were not recomended for use from cannons. Is that correct then? As for the melting my neighbor has been melting down car part aluminum in his garage from cars he salvages out so there is plenty there and he is interested as well.
 
Jeff
PHsarge

[Artilleryman]

I have tried aluminum projectiles in a 12 pdr mortar.  Wind drift is a big problem, and small variations in powder charges produce large differences in range.

Do you recommend solid iron?

No.  Mortars were designed to throw shells.  A 12 pdr would throw about a 8-9 lb shell, a 24 pdr about a 16-17 lb shell, an eight inch a 45 lb shell (solid is 65 lb).

[Artilleryman]

What I had read was they were not recomended for use from cannons. Is that correct then? As for the melting my neighbor has been melting down car part aluminum in his garage from cars he salvages out so there is plenty there and he is interested as well.
 
Jeff
PHsarge

I have tried aluminum projectiles in my 12 pdr with mixed results in accuracy.  They may work alright out to 100 yards, but at they don't do as well as full weight projectiles.

[Zulu]

I cast these for a 3" bore a while back when I had access to an aluminum foundry.  They weigh 1.1 lbs. each.  The same ball in lead was 4.8 lbs. and in zinc was 3.1 lbs.  I never fired one of them.
Zulu
 

[Artilleryman]

I recommend zinc for casting cannon projectiles as it is very close to the weight of iron.  The only problem with zinc is that there always seems to be a void under the sprue, the larger the projectile the larger the void.  It takes extra work but the voids can be filled.

[GGaskill]

Zinc will give the best weight in a material that is readily cast at home, but unless you are in competition, I see no reason why aluminum wouldn't be just fine. 

At CBC² I, we cast a bunch of zinc shot and at the beginning, we had the internal void problem.  We postulated it was caused by the sprue solidifying before the insides did.  Then we started playing a propane torch on the sprue until the shot would suck no more liquid metal inside and this gave us shot of uniform weight without the voids.  I guess you could make the mould so there was a volume of liquid metal over the sprue to supply the shrinkage and stay hot enough to remain liquid but the mould we used was not set up that way.

[Artilleryman]

The use of a torch is a good way to go.

[Cannon Cocker]

Norm has got it right.  Zinc is a great substitute for the iron that was used in the time periods we model our guns after.  It has a specific gravity of 7.1 and iron is 7.8 (very close).  Lead is 11.3 and aluminum is about 2.5.  Lead causes unwanted pressures and aluminum has no range and gets blown around more.  Lead is popular because its easy to cast.  I cast lead bolts but they are much shorter than the iron bolts that would have been used in the gun to make up for the added weight.  When I shoot round balls I shoot zinc because the shape can't be modified to make it lighter.  Looked into sand casting hollow lead balls but then the work is much much more than casting zinc.  I cast zinc balls in an aluminum mold and don't seem to have the problems I have heard others talk about.  It just gets a little chalky and I clean it up once in a while.  If you've cast lead before you may be able to cast zinc with the same heating system.  I think the melting temp is only about 150? degrees more.  It takes some getting used to though.  It's kind of slushy and doesn't flow as easy especially if its not quite hot enough.  If the feeding head is big enough (sometimes it's not with a mold that was designed for lead) the little void that Norm was talking about can be less of a problem.  Another nice thing about zinc is that after I'm done casting a bunch balls all I have to do is hold on to the ball and whack the sprew with a little hammer and is snaps right off clean.  No hack sawing the sprew off and getting lead dust everywhere.  Also, I dig my zinc balls out of the berm and keep shooting them.  Unless you hit a big rock you can just keep using them.  Almost makes up for the harder process of making them. 

[guardsgunner]

Safe, yes.  Fun to shoot. yes.  If the material is free definetly.  As accurate as zinc, no. Have to be cast around a core as zinc, no.
Unless you are getting real serious about competion, I would use them, especialy if all it cost is time.
 
Fun is fun and winning isnt everything.
 

[Double D]

Zinc round balls  for golf ball,  popcan and 6 PDR are available for RotoMetals  See the GBO Group buy post in the classifieds.  http://www.gboreloaded.com/forums/index.php/topic,219140.0.html