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Alstone · Moderator & Site Supporter

After looking at the pellet photos posted by Brutuz, it inspired me to have a go at making a mould for a straight sided pellet as used in powder burners, and give it a try out.

The mould is made out of two pieces of 16mmx 30mm x5mm steel strip, these are clamped together and two dowel holes drilled to line up the sides when casting a pellet, the hole for the pellet was drilled out 3.5mm to the depth required and then opened up to the finished size of 4.4mm (.177 ), this is slightly smaller to give clearance in the barrel, the drill tip is ground to the shape required on the pellet.

The mould sides are smoked with a candle to stop the hot lead sticking, clamped together and heated up to about the temperature of boiling water, melt the lead in a spoon and pour into the mould, when it has set chop the waste off with a Stanley knife.

I drilled out the base of the pellet with a 3.5mm drill and flared it slightly to make it a good fit in the barrel. ( I intend to make an adapter to fit on top of the mould to locate the hole in the base correctly ).

To test the pellet I made six altogether, the finished weight is 14.66 grains which for a .177 slug is quite heavy, using a AA Field pellet 8.4 Grains (as a standard ) I fired them into a bucket of sand to check the difference in fps The standard was 785fps and the “special” 605fps, this by the way was using a QB-78 rifle. Using a 25m target and my TX the grouping was 15mm for the special, the AA Field was hole on hole, using a bench rest.

One thing that did surprise me was the amount of energy they carried at 25m, they certainly rattled the back stop, but not accurate enough yet. I think I will have to work on the tail a bit to improve stability.

FINISHED PELLET

MOULD AND LINING UP PINS

SMOKED MOULD

FIRING TEST INTO SAND

Al

Midichlorian · Veteran Member

Wow,I would buy um.
Are you making .22?
How are they shooting?

Brutuz · Senior Member

Very interesting Cool

fritz · Silver Status Member

More pictures of more pellets from different angles. Please.

Did you hone the flat face of the mould? Why does Firefox automatic spell check think "mould" is not a word?

Alstone · Moderator & Site Supporter

Midichlorian I am just experimenting with .177 for now, making them one at a time is labour intensive, and at the moment they are a bit unstable.

Fritz Mould is English for “Mold” as in “jelly mold”. I have to make a new one so that I can change the tail of the pellet and also incorporate a jig for drilling the base hole.

Only the mating faces need to be flat and I do this with a file.

Al

fritz · Silver Status Member

That's what I meant: "mating faces". I was wondering if you had just left the faces stock and rough from the steel mill. Did you use a drill press to drill the alignment holes?

I was taught to spell the thing you form stuff in a "mould". "Mold" is the fungus.

jlwilliams · Veteran Member

Neat project. This could open the door to making an airgun in whatever caliber you may want to try. This could also become the only way to hunt in the unlikely possability that airgun pellets get regulated out of availability or somehow otherwise get hard to come by. Regardless of wether or not you ever NEED to make your own, you certainly learn more trying this than I learned buying a tin at WalMart last week.

I'll watch your progress with anticipation...

Alstone · Moderator & Site Supporter

I have just had a thought that I didn’t check the fpe of a 14.66 grain pellet @ 605fps, I now find that it comes out at 11.9179 fpe which is very close to the UK limit for air rifles of 12 fpe, so I will have to be careful with the weight and keep it below 14 grain for safety. UK air gunners take note.

Fritz the mould was drilled out using a drill press, but a hand held drill should be ok, make sure the hole is on the center line, and dowle the two side plates together before drilling the hole, I used taper pins for alignment but stright sided dowles would be ok.

I,m away from home at the moment so I can't get on with anything, but I will make a new mould next week and give it another try.

Al

Slavia · Moderator

Interesting project. I think you're breaking new ground with this one - I don't recall seeing anything before on DIY cast pellets.

I've been casting muzzle loader bullets for 20 years. You probably already know this stuff, but just in case:

1. The molten lead will "skin over" with oxidation. Throw in a pea-sized piece of paraffin and after it burns off, that skin (and any other impurities) will be chunky and easy to spoon out.

2. My (commercial) moulds are made from aluminum, probably so they will warm up faster. It might also be easier for you to machine. (Aluminum melts at 1220 Deg. F., and lead at 621.)

3. My first few pours result in oddly shaped lumps, because the lead is freezing in the sprue. After the mould warms up you can watch the lead in the sprue slowly freeze. The trick then is to maintain a rhythm - pour, freeze, cut the sprue waste, eject, and repeat before the mould cools down.

4. Have plenty of ventilation - breathing in lead can't be good for you. I do my casting with an electric hot plate on a concrete floor (as opposed to a pot sitting on the kitchen range). I figure that way if there is a spill, the fireproof floor gets it and not me.

Alstone · Moderator & Site Supporter

Hi Slavia I have a small electric lead casting pot which is temperature controlled and just use a perforated ladle to clear the dross, but Paraffin wax sounds good I may give it a try.

I prefer steel for moulds I find them are more stable for fine casting, also there is less wear on the mould if you use a built in sprue cutter.

Your right about safety hot lead sticks. Laughing

Al

kanyon · Silver Status Member

Alstone · Moderator & Site Supporter

Had another go at a pellet mould Brass this time, with a smaller body diameter 4.5mm and two rings of 4.52 mm, hoping this design will be a bit more stable than the last effort.

The finished pellet which is solid and weighs a heavy 20 grains which for .177 is very heavy, (maybe all right if you have 30-40 fpe to play with). Anyway they are still unstable so much so that one hit the baffles in the silencer on my TX.

Thinking about it I don’t really want a 20g pellet anyway so I will have to alter the new mould so I can drill out the pellet base accurately.

Pete It would be difficult to poke something in the back of the mould to make a hole in the base, as the lead goes cold almost instantly and to keep the lead soft long enough to do this, would mean the mould being as hot as the lead, which wouldn’t be practicable.

So I think the MK 3 mould will have a shape like the MK 1 but with more of a flare on the base and drilled deeper to lessen the weight to about 10grain. Of cause unless anyone has got an idea for getting better stability with this pellet shape.

Back to the drawing board. Laughing

Al

dogon1013 · Member

Those heavy weight pellets will require a faster rifling twist to be able to stabilize, especially since they are moving slower most likely. (same issue with firearms)

Any idea what the twist rate is in your airgun? you could then calculate what the heaviest pellet you could stabilize would be.

Simply shortening the pellet up a little will help with stability, or just drill with a smaller diameter drill deeper so more mass is concentrated at the outside of the pellet (Just like a top is very wide, with most weight to the outside). That will also help with stability.

Instead of drilling from the back, you could turn it into a hollow-point by adding a pin into the bottom of the mold. This would be like drilling with the smaller drill, but it would be molded that way.

Alstone · Moderator & Site Supporter

Hi dogon1013.
Yea! I think I have run out of power and to little a twist rate, the last pellet was solid just to see what would happen, but like you say it would need a higher spin rate, plus airguns tend to have a gentler twist than powder burners, the ratio of the TX I was using is 1.25, which is a bit higher than most due to the shorter barrel.

I will leave the length of the pellet as it is and bore out the base to about 2/3rds of the length, and also flare the skirt a bit more.

The whole idea is the get a straight sided pellet to shoot well so that I can auto feed them into a breach, where as Diablo is difficult to feed without damaging the skirt.

Al

Griff1950 · Member

Making hollow base pellets isn't difficult, you just have to flip your thinking over. Cast the bullets upside down, cut them off at the nose rather than the base. This makes it relatively easy to install a base plug of whatever size and shape you would like. A bullet or pellet must have an accurate base to be accurate, the nose isn't nearly so important, so make sure your mould has a nice even base.