When a ball slips!

[Britsmoothy]

I was wondering the other day, a dangerous situation I know but I have often wondered why low charges as a general rule often do not offer the best accuracy in many patched ball rifles.
So I started trying to imagine what possibly could be going on down near the breach upon ignition.
I then wondered if a ball under pressure moves forward in the patch a fraction.
If so that would leave some patch material loose....well not loose onset pressure no but what about on leaving the muzzle!
It could tip or influence an irregular input to the ball as it leaves the barrel with the gasses also present!
Is this why wads under a patched ball sometimes work!?
What say ye? Hog wash or ......

B.

 

[BrownBear]

... I know but I have often wondered why low charges as a general rule often do not offer the best accuracy in many patched ball rifles.

....well not loose onset pressure no but what about on leaving the muzzle!
It could tip or influence an irregular input to the ball as it leaves the barrel with the gasses also present!
Is this why wads under a patched ball sometimes work!?
What say ye? Hog wash or ......

I've tried enough of my own rifles and those of friends with low charges to convince me that the finger points at another culprit- Slow twist rates. Down around 1:48 most rifles deliver stellar accuracy with light charges, as good or better than the best large-charge loads. Get up to around 1:70 or slower, and light loads stink. Each rifle is an entity unto itself, but that's sure been the pattern among the many rifles in our neighborhood. Since so many original rifles are 1:48 and our forebears were reportedly prone to lighter charges, perhaps they knew a lot more than we do.

As for wads under a patched ball improving accuracy, we've traced that mostly to too loose a patch/ball combo. It's nice for hunting and not using a short starter to be able to get good accuracy with a looser combo by adding the patch, but the same rifle can usually do away with the wad if patch thickness or ball diameter are increased enough to call for some extra effort in starting and seating.

Like I said, each rifle is its own individual self, but among over a dozen active shooters with something close to 100 rifles between us, both those patterns hold true. Next one through any one of our doors might be different, but for all of us those are the starting points in figuring out loads.

 

[BEP]

It's fun to speculate on such things but the pressure from the gasses generated by the gunpowder igniting are transmitted to the ball via the patch, pushing said patch even tighter against the ball than when when it was loaded.

 

[Britsmoothy]

Excellent replies. Maybe my theory is flawed.
My only possible defense could be the loose ball patch combo.
The pressure has to build and I know it is an extremely short time but at low pressure could the ball be moved forward in the patch....I dunno, it's all speculative....I just like thinking out loud.

Sorry admin for posting in the wrong department earlier.

B.

 

[bang]

The pressure behind the prb is higher than the friction ahead. The prb moves as one unit.
If you can press the prb into the barrel with thumb pressure it's too loose.
Bore - .010 typical ball size. Sometimes a .015 patch still makes fit better than a .010. Just depends on bore max.
My 45 measures .456. A .440 and .020 work great but also a .451 and .010. The .440 and .020 shoot better. More patch locked into riflings.

 

[Loyalist Dave]

The light loads may = zero obturation. Now there are folks who think there is major obturation (ball flattens itself into the rifling). Some of the fellows who repeatedly whang their ramrods when loading the ball will say they are trying to manually force the ball onto the rifling. Expert long range marksmen have written that this is not a good idea. So I don't think it's the ball nor the patch are the key, as I don't think significant obturation if any, happens at loading nor firing of the patched, round ball....

It was/is also known that for rifling to have any impact, the ball must get at least ¼ turn before exiting the barrel. IF you look at the twist rates, you will note however, that most of our barrels give a bit more than a ½ turn before exiting. A 1:56 twist barrel that is 38" long (such as mine) the ball has done a ½ turn when it reaches 29 inches (allowing an inch for the powder charge), but continues for another 9 inches. A 28" 1:48 twist barrel on a plains rifle, ½ turn is achieved at somewhere around 25-27 inches, give or take the amount of powder and caliber.

What we don't realize though is that the speed at firing imparts that spin at different RPMs for different loads. Lighter loads have slower RPMs imparted to the ball, than heavier loads.

In other words imagine an antique toy top.

The string is the same length whether you launch the top or I launch the top. However IF I pull twice as hard when launching that top as you, I will impart higher RPM to that top. The same would be true for you using a light load in your rifle, and my using a stout load.

So there is something going on with the RPM imparted to the ball due to the MV when it exits. So there may be some sort of minimum RPM x diameter of the round ball x distance in flight, that is in play when we shoot....

That's my S cientific W ild A rsed G uess aka SWAG

LD

 

[Dr5x]

ASKING WHAT A LOW CHARGE HAS ON ACCURACY IS SIMILAR TO ASKING WHAT A WEAK ARMED PITCHER WOULD PERFORM IN A BALL GAME.
IF THE BALL MOVES IN ITS PATCHING WOULD BE A GOOD EXAMPLE OF A TOO LOOSELY PATCHED BALL.

THE IDEAL PATCHED BALL WILL HAVE THE PATCHING AND SOME OF THE PERIPHERAL LEAD OF THE BALL CRUSHED INTO THE LANDS AND GROOVES OF THE RIFLING. AND FORMING A SEAL TO KEEP ALL THE PRESSURE BEHIND THE BALL/PATCH COMBINATION AND ALLOWING NO BLOWBY OF THEEXPANDING GASSES.
WADS ARE EFFECTIVE IN COMPENSATING YOU A TOO THIN PATCH MATERIAL.
IT SHOULD BE BEST TO HAVE PERFECT PATCHING. USING WADS IS COMPARABLE TO USING TRAINING WHEELS ON A BYCYCLE.

DUTCH SCHOULTZ

I was wondering the other day, a dangerous situation I know but I have often wondered why low charges as a general rule often do not offer the best accuracy in many patched ball rifles.
So I started trying to imagine what possibly could be going on down near the breach upon ignition.
I then wondered if a ball under pressure moves forward in the patch a fraction.
If so that would leave some patch material loose....well not loose onset pressure no but what about on leaving the muzzle!
It could tip or influence an irregular input to the ball as it leaves the barrel with the gasses also present!
Is this why wads under a patched ball sometimes work!?
What say ye? Hog wash or ......

B.

 

[yonderin]

Interesting idea.

I think the top becomes unstable at the same rpm regardless of which of you starts it, just that launching it at a higher rpm initially delays the time it takes to become unstable (translating to further down range for a projectile). Good for our application.

But, a difference that complicates your theory, in my mind, is that the top is balanced on the end of it's axis which is outside the main body of it as opposed to being contained completely within it.

This old, slow mind will need some cogititating on it. But I do think it helps explain the problem at least partially.

 

[Col. Batguano]

This is interesting, and the 1/4 turn thing would help explain why ML'er pistol barrels typically have faster twist rates then the same caliber in a rifle barrel. I always thought it was because of the relatively slower velocities out of a pistol, but apparently that isn't so.

In C&B revolvers, do snubbies have faster twists than their longer barreled versions in the same caliber?

 

[Elkeater]

With a proper patch and ball fit in the barrel, snug but not overly so, it doesn't matter how long the barrel is. Rate of twist being the same the air born ball will obturate the same.
Sorry Brit, off topic.

 

[45man]

Dutch Knows best as I have learned longer then most here were born. The patch must engrave .005" at the grooves. Forget the lands. Fit is the king. Then comes the lube. Some fail utterly. Even a Minie" ball needs fit and if you think an expanding skirt makes it run true, look again.
Most want a patched ball to fall in easy. You are wrong. The correct is a karate punch on the starter. Not a hammer either. Toss the mallet. Even a .002" difference will make a load shoot or not.

 

[45man]

This is interesting, and the 1/4 turn thing would help explain why ML'er pistol barrels typically have faster twist rates then the same caliber in a rifle barrel. I always thought it was because of the relatively slower velocities out of a pistol, but apparently that isn't so.

In C&B revolvers, do snubbies have faster twists than their longer barreled versions in the same caliber?

Twist is ignored too much and is so important it is crazy. I have always said the shorter the barrel, the faster the twist because of loss of velocity and spin. But NO a revolver C&B does not change. It should.
I hate to get modern here but the analogy is the same. Magnum Research makes BFR revolvers with faster twists then anyone else. No revolvers on earth shoot as good. Can you shoot a PRB from a 1 in 28" twist from an inline? It is bearing surface of the ball or bullet.
The net is full of bullet length and it is wrong, it is bearing surface no matter the length. You could put a 2" nose on a RB but the bearing surface will be the same.

 

[Tb54]

I like Dave’s top theory. The fast spinning top shows some wobble, or instability. As it slows it’s RPM it becomes more stable, until it slows even more and becomes less stable again. By influencing foreword velocity on the projectile, we are influencing the RPM rate—two isolated forces on the projectile. The most stable spin rate, combined with barrel vibration and air resistance, gives us the most accurate combination.

IMO