Accuracy with a loose load in a smoothbore

[Robert Egler]

I’ve been shooting my new GM 54 smoothbore, and after getting a load that worked well with shot I decided to see what I could do with prb. Unfortunately, I didn’t have anything except 0.490 balls, the others haven’t arrived yet, but I figured I’d just go ahead and see what happened. (Besides, it was a nice day and I didn’t want to go home yet, and it was a good excuse to burn more powder.)

So I tried a 0.490 ball with double 0.015 patching. I would think this would be a bit loose in a 54, since it only adds to 0.520 (used 85gn FFg). It was smooth loading, not “easy” but not really needing a lot of pressure, which I figured was normal with a loose ball.

Well, I was a bit surprised by the results, at 30 yards from a bench I had a three shot group where all the holes touched. That’s a lot better than I expected from this load.

I know that 30 yards isn’t very far, it was 30 yards because that’s the distance I was patterning at. I’ll have to try more shots, and at 50 yards, and see what I get, but extrapolating that to 50 yards it's about as good as my 50 cal rifle barrel.

Is this not really a loose load? This is my first smoothbore and I’m not sure what to expect.

 

[Britsmoothy]

It goes a long way to demonstrate how versatile a smoothbore is, well done :thumbsup:

 

[paulvallandigham]

Try that same combination with an OP wad to seal the gases better and you should get even better results. :thumbsup:

 

[Many Klatch]

For fun try it with a leather patch. Sounds like you are on the right track.

Many Klatch

 

[Cutfingers]

I use a .600 ball in my 62 with a punched card and a .010 patch. It shoots outstandingly. 70 grs of FFF and primed w/ FFF.

 

[papellet]

The fun with smoothies. I load the powder, over powder wad, drop a .610 ball down the barrel with no wad, then an over shot card. Works real well.

 

[tg]

Looking back over the last 30 years, it would be nice if wives were as forgiving as smoothbores...

 

[vikinghick]

Am I off-base when I say 2 .015 patches would add .060 to the diameter? The patch is on both sides of the ball in diameter and with 2 patches x 2 sides X .015 = .060. On top of the .490 ball that would be .550 right?

-Craig

 

[paulvallandigham]

You are correct. :thumbsup:

 

[CoyoteJoe]

Nothing wrong with your math, but math doesn't get you very far because you can't factor in the compression of the cloth. Cotton compresses more than linen, a tight weave compresses less than a loose weave, dry leather compresses very little, wet buckskin compresses a great deal, etc. I have some .020" linen canvas which seems tighter than some .028" cotton canvas. Also, what one person considers to be "a tight load" may be what another person considers rather loose. When I load that .028" canvas with a .490 ball I'm stuffing a total of .546" patch and ball down a .500" bore with .524" grooves. Some will say that is impossible tight and it does require a smart rap on the ball starter but once started it is not really hard to run on down. The point being that a strictly mathematical approach won't get you more than a rough idea, if even that. :grin:

 

[Robert Egler]

Am I off-base when I say 2 .015 patches would add .060 to the diameter? The patch is on both sides of the ball in diameter and with 2 patches x 2 sides X .015 = .060. On top of the .490 ball that would be .550 right?

-Craig

Yeesh! Yep, you're right. There's a reason why my wife doesn't let me balance the checkbook!! :redface:

Anyway, I can start it without a short starter, and it goes down easier than the same ball and 1 patch in my .50, which is the recommended combination for my .50, and shoots well.

Never minding the math, I'm happy with the result.

 

[roundball]

Am I off-base when I say 2 .015 patches would add .060 to the diameter? The patch is on both sides of the ball in diameter and with 2 patches x 2 sides X .015 = .060. On top of the .490 ball that would be .550 right?

-Craig

Yes, but also remember that patch material can compress almost in half when forced into a muzzle...

 

[paulvallandigham]

Patch compression depends on how wet the fabric is( juice vs. grease) and whether you are shooting a rifle, or smoothbore. A smoothbore has no place for the fabric to compress into, and that is probably why this attempt at using undersized balls resulted in such good short range accuracy. The double patching gave a good seal, but did not have to transfer the spin of rifling to the ball.