Boolit length

[hnusz]

I'm playing with the idea of making my own molds can't find what I'm looking for. I work in a machine shop. I pretty much got the how to make them figured out. My question is powder weight and coal is determined by boolit length not necessarily weight?

[BamaNapper]

If you think about it, boolit weight is pretty closely tied to boolit length. Obviously a boolit has a given diameter. So the longer you make it, the heavier you make it. It's a cylinder with material removed for the bands and shaping the nose. A 200gr boolit is going to be longer than a 125gr boolit for a given caliber. If you maintain the same COAL, that means you have more of the 200gr boolit in the case. The more boolit you have in the case, the less room you have for powder. But the heavier boolit may need more room for powder. The only option is to increase the case length or diameter. And that is how the 38 progressed to the 38 Special, and finally to the 357 Magnum. It's a quest to push heavier bullets faster.

If you're using a decent 3D CAD software to draw your project to be loaded to an automated machine, the software will be able to give you the volume of the cavity. Pull the cavity out as an object, tell it that it's made of lead, and it will give you a good approximation of the weight. The alloy of your lead will change it a little, but not much. Play with shapes and lengths in the software until you have your desired weight. If you can't extract the cavity tell the software the whole thing is mad of lead and compare the weight with /without the cavity.

Good luck. Sounds fun.

[hnusz]

No cnc in the shop everything is conventional. I guess what I mean is 240gr lswc in 44mag is a certain length if I extend its length to the length of a 300gr lrn wouldn't I load it like it's a 300gr because their lengths are the same even if their weights are not. All boolit

[JonB_in_Glencoe]

The powder charge should be worked up and a starting charge is dependent on boolit weight...but is also dependent on case capacity after the boolit is seated, than it is on length of boolit.

Another thing to consider is barrel rifling twist rate. It's best to design your boolit with the optimal bearing length to match rifling twist for best stability ...and don't confuse bearing length with boolit length.

[Winger Ed.]

Look at the loading manuals and how they are written for a given cartridge.

Its all about powder charge & bullet weight, and the pressure limitations of their various combinations.
The OAL just has to jive up with those things and still fit the chamber.

Not to discourage ya:
I very much envy someone who can, and does make their own molds.
However; if you don't have some specific idea or purpose for a new boolit shape & weight-

Rather than trying to re-invent the wheel, or go off into uncharted waters:
I'd copy, or tweak a mold design that has been around at least a few generations, and has stood the test of time.

[JSnover]

For a given length/diameter you can tweak the weight by changing the nose profile and the number, depth and shape of the lube grooves; straight-sided, tapered or rounded, deep vs. shallow.