Speed of lead ball

[hortonstn]

Anyone got a clue of the velocity needed to stabilize a patched round ball for a 45 cal ball in  42"
Barrel?

[smallpatch]

That’s something you’ll need to figure out with you powder/patch/ball combo.
Stabilization can happen at very low charges.  You’ll have to figure out how much power you need for accuracy/ knock down power.

[rich pierce]

Stabilization is a dance between velocity and twist rate and ball diameter. The slower the twist rate, the faster and further a ball must travel to get the same rpms. Barrels with faster twist rate cause the ball to need less velocity to get the same spin rate.

[D. Taylor Sapergia]

....and stable, at what range?

[hortonstn]

1-66 twist target at 60 yds
Thanks for your replies

[rich pierce]

Well with a .45 at 1 in 66 I’d suggest starting at 60 grains of FFFG.

[Daryl]

That load sounds logical to me, Rich & is a good place to start.
Ball RPM is not everything, however. It takes very little spin to actually stabilize a round ball in flight, but - will it be accurate, even though stable?
Different ball and patch combinations produce different velocities and rpm as a result, however the burning of the powder producing consistent internal
ballistics & close shot to shot velocities/pressures, is also important in delivering accuracy, not just the rpm produced. I've found in a number of different
rifles that changing the lubricant changed the way the ball and patch combination shot accuracy wise and I had to re-work the accuracy load by increasing
the powder charge. In two rifles this produced roughly 300fps increase in velocity, yet the accuracy was then the same as it had been before, even though
the RPM was also increased due to the increased velocity. The reduced drag or friction caused by the more slippery lube, changed the dynamics of the way
the powder burned in that the shot to shot  pressure fluctuated more, resulting in greater shot to shot velocity spreads, which changed the accuracy in a negative way.
 By the time accuracy and shot to shot consistency was re-established, 10gr. more powder was needed along with the resultant velocity increase, thus change in RPM as well.
Thus, in a .45 rifle, 65gr. which shot well with a water based lube and 10ounce denim patch and .445" ball. When I changed the lube to LHV, similar to Mr. Flintlock\s lube
I had to increase the charge by 10gr. before the load's previous accuracy was again met. This was in a GM barrel, .45cal. and 60" rate of twist.
A very similar occurrence happened in a .40, with 48" rate of twist.  Incredibly, the resulting velocity of the .40 cal ball was the same as .45 cal ball, with both rifles running
over 2,200fps with the new accuracy loads & producing 1/2" groups at 50 yards, rest shooting.  Big difference in RPM, yet both rifles shot the same, with 10gr. less powder
and a water based lube. The lube itself was the reason, not the rpm.

[Jeff Murray]

All good info.  Don't forget to check your patches to make sure they are intact after being shot, and that your patch/ball combo are a tight fit. 

[Dphariss]

Anyone got a clue of the velocity needed to stabilize a patched round ball for a 45 cal ball in  42"
Barrel?

Given that I have had some reasonably accurate pistols with 66" twists the SPEED does not mean much. Since the 50 cal 6" pistol shot pretty well at 800 fps.  Forsythe got good results with 10 and 12 foot twists in 69 caliber rifles at  +-1600 fps. (calculated from his trajectories).
However, many rifles shoot best with higher velocity, but there are other factors like barrel harmonics which with the RB is probably more important than the twist rate for accurate shooting. So its more to do with the what the barrel likes than "stabilization" of a round ball. Which really needs little RPM. I have a 66" twist 54 that runs about 1900 at the muzzle this will shot a 54 Rb into 6" at 200 yards with no wind. I just used a formula from the WWW and got 2O,727 RPM. Even at 800 fps like the 6" pistol made I get  8,727 RPM.  Though the Berger Bullets Stability calculator tells me it should have a 1:13 twist (105,230 RPM). Which of course is silly. Greenhill's formula for early 19th c artillery shooting elongated projectiles gives a 80 1/4"  twist (17046 rpm at 1900 fps).   
Some modern calculators get crazy when ML and RB parameters are entered. I suspect the Greenhill is a little off  but not much. It is for other small arms.
All this said for calibers under 58 I think the 48" is better than most. But it would take a number of barrels in several different twist rates and a lot of powder and lead to prove it. And they might all come out even anyway.
BTW I have a HV brass suppository match rifle that runs 277,714 rpm.  So you see the RB does not need much for stability by comparison.
Dan
In case I typoed the rpm calculator its here.
http://bulletin.accurateshooter.com/2008/06/calculating-bullet-rpm-spin-rates-and-stability/

[Dphariss]

Well with a .45 at 1 in 66 I’d suggest starting at 60 grains of FFFG.

Agree.
Back in the 60s when most barrels were 66" Douglas or maybe 56" Bill Large, this was pretty much the standard load for 45 from what I remember.

Dan

[Dphariss]

That load sounds logical to me, Rich & is a good place to start.
Ball RPM is not everything, however. It takes very little spin to actually stabilize a round ball in flight, but - will it be accurate, even though stable?
Different ball and patch combinations produce different velocities and rpm as a result, however the burning of the powder producing consistent internal
ballistics & close shot to shot velocities/pressures, is also important in delivering accuracy, not just the rpm produced. I've found in a number of different
rifles that changing the lubricant changed the way the ball and patch combination shot accuracy wise and I had to re-work the accuracy load by increasing
the powder charge. In two rifles this produced roughly 300fps increase in velocity, yet the accuracy was then the same as it had been before, even though
the RPM was also increased due to the increased velocity. The reduced drag or friction caused by the more slippery lube, changed the dynamics of the way
the powder burned in that the shot to shot  pressure fluctuated more, resulting in greater shot to shot velocity spreads, which changed the accuracy in a negative way.
 By the time accuracy and shot to shot consistency was re-established, 10gr. more powder was needed along with the resultant velocity increase, thus change in RPM as well.
Thus, in a .45 rifle, 65gr. which shot well with a water based lube and 10ounce denim patch and .445" ball. When I changed the lube to LHV, similar to Mr. Flintlock\s lube
I had to increase the charge by 10gr. before the load's previous accuracy was again met. This was in a GM barrel, .45cal. and 60" rate of twist.
A very similar occurrence happened in a .40, with 48" rate of twist.  Incredibly, the resulting velocity of the .40 cal ball was the same as .45 cal ball, with both rifles running
over 2,200fps with the new accuracy loads & producing 1/2" groups at 50 yards, rest shooting.  Big difference in RPM, yet both rifles shot the same, with 10gr. less powder
and a water based lube. The lube itself was the reason, not the rpm.

Hi Daryl
I had been shooting tallow and Don King's formula "Gunsmith's Grease" on patches or a patch wet with Pure Neatfoot Oil in my 50 cal swivel. All "slick" patch lubes. After some info from a friend and some thinking.  I cut the NF oil WAY back to just a few drops 2-3 on each patch then let it migrate through the whole patch over night or a little longer. The rifle seems to shoot a lot better in our offhand matches and I need to bench it. I think this is because, like the water bared lube this light oiling is higher friction. I can still shoot about as long as I want with a blow tube using 70 gr of FFF Swiss. Sperm Whale Oil is notably higher friction than almost anything I have ever used and was a favorite of old time riflemen.  It tends to load hard even with a clean barrel. But I only have maybe 4 ounces left. A friend has a rifle that really will not shoot with anything else but he only uses one or two drops per patch.
Just some random thoughts. I use a very dry patch in my heavy chunk rifle too. Water soluble cutting oil about 1:5 or 1:7 oil:water. Soak the patches then let the water evaporate. Wipe every shot and it really shoots.

Dan

[Daryl]

Makes sense, Dan, that minimal lubes could be more accurate.
It all boils down to what is needed (the goal) and what a person will do in this process, to achieve that goal.
That the higher friction of the water based lubes causes even pressure and closer shot to shot velocity
variations at lower charge weights than did slippery lubes at the same loading, also makes sense.
Taylor also hit on a variable that is pertinent to our shooting, that of "at what range do you want the best accuracy"?
We know that to shoot accurately at longer ranges, requires more powder.
 For instance, to shoot accurately, say 1/2" groups at  the very close range of 20 to 25yards with a rifle, you can use a
powder charge that will barely hold 2" to 3" at 50yards,  yet increasing that powder charge will steadily improve the accuracy
 at 50 or 60yards.  Then again, to shoot  well at 100 yards, requires yet even more powder.  Even then, the accuracy at 25 yards,
 with these heavier powder charges will be seen to be identical to the lower charge shot at that range originally.  I know many people
 have different powder charges depending on the range they are shooting, for example 50gr. for 25 yards, 60gr. for 50 yards and 80gr.
for 100yards, or 50gr. for ranges out to and including 50yards and 80gr. for 100yards.
This, in part, is due to elevation requirements of the fixed sighted rifle, as well as increased rotational speed required for shooting
at the longer ranges.
What it amounts to, is experimentation. Simply picking a patch material & thickness, a ball diameter and X powder charge and expecting
this to be the ultimate, is an exercise in foolishness.  With enough experience though, we know that certain combinations will be close in
a wide range of calibres.

[Silent Walker]

Follow the directions on the page... easy way to check

http://ctmuzzleloaders.com/ctml_experiments/rbballistics/web_apps/rb_webapps.html