Are big bore short barrels more efficient than smaller bore short barrels?

[Philip A.]

I see that higher loads for many bore sizes tend to be in the 90 to 120gr of powder, i.e. similar charges for vastly dissimilar bore capacity.

Does this mean that you'd get a better burn in a, say 28" barrel in .62 than in a 28" .50?

In other words, do larger bores allow you to build shorter rifles with no significant velocity loss?

 

[andy52]

This question would be all about math and I don't think a generalization would be a good answer.

 

[Grenadier1758]

I'd have to find my Lyman Muzzleloading manual with all sorts of tables of ball diameter, powder charges and velocities. If I remember correctly, the larger balls need more powder to get the balls moving.

 

[earlwb]

Simple physics a bigger heavier bullet needs more propellant than a smaller more light weight bullet to get moving.

I think it is more about knockdown power. The bigger caliber bullet has more stopping power than a smaller bullet. Modest velocities work well too.

 

[Philip A.]

Simple physics a bigger heavier bullet needs more propellant than a smaller more light weight bullet to get moving.

I think it is more about knockdown power. The bigger caliber bullet has more stopping power than a smaller bullet. Modest velocities work well too.

Yes, heavier balls need more powder to get the same acceleration...

But the question is, given a barrel of same (short) length, since the volume of the barrel is larger, will a bigger bore burn all the powder, vs a smaller bore with same charge spitting unburnt powder out?

 

[ETipp]

Yes, heavier balls need more powder to get the same acceleration...

But the question is, given a barrel of same (short) length, since the volume of the barrel is larger, will a bigger bore burn all the powder, vs a smaller bore with same charge spitting unburnt powder out?

Yup, it’s that way with any firearm. The most efficient load is the one where all the powder is burned up as the projectile reaches the muzzle. If the powder is burned up prior to that, then the projectile has more drag. If the powder is not completely burned up by the time the projectile leaves the muzzle, it can contribute to poor accuracy. You are not gaining a thing anytime unburnt powder is being pushed out of the barrel. In fact, in many cases, it is counter productive and can contribute to a loss in down range accuracy.

 

[Freedom]

Larger diameter bores are more efficient at producing energy from a given powder charge.
Velocity only being "one" of the components to energy.

This calculator is a lot of fun to play with.... https://www.p-max.uk/cgi-bin/black_powder.cgi

 

[Philip A.]

Larger diameter bores are more efficient at producing energy from a given powder charge.
Velocity only being "one" of the components to energy.

This calculator is a lot of fun to play with.... https://www.p-max.uk/cgi-bin/black_powder.cgi

Thanks, that's a good link!

As for energy... In my 20s I used to spend lots of time perusing ballistic tables and energy figures, wishing for more whizz-bang than my whizz-bang of the day. Then I went to live in Africa, and proceeded to shoot stuff.

Well... I found out that energy sells guns, but doesn't kill stuff

Holes in the right spot kill stuff. And bigger holes empty the bucket faster...