Your Educated Guess Please

[OldMtnMan]

I don't have a chrono or know anybody who has one. This is a curiosity question more than anything. I learned a long time ago to not pay attention to ballistics for a PRB.

So, with that in mind. What's your best guess at my MV on this load?

Caplock 28" barrel.
.50 PRB with fairly tight fit.
Swiss 3F 75gr.

Thanks

[L. Akers]

From charts I have found I think you'ld be close to 1800 fps.

[mtlonghunter]

Years ago Lyman had a black powder book with all kinds of powder loads and barrel lengths in different calibers and the muzzle energy, muzzle velocity and foot pounds at 100 yards. I don't know if they still publish it but you may find someone here with an old copy.

[OldMtnMan]

I was guessing around 1800fps too. That's probably pretty close, but i'll keep snooping around.

The real test will be when I get the elk in my sights. Hopefully, that will still happen at my age.

[Hungry Horse]

My 50 cal. Tryons with a 32" barrel went 1600 fps. on a crony with 80 gr. Of Goex 3f.

  Hungry Horse

[Daryl]

I would expect no more than 1,700fps with the Swiss 75gr. load.

Also, the velocity obtained depends on the tightness (seal) of the ball and patch combination.

S. Fadala received higher velocities when he used a wad of some sort between his patched ball and the powder. 

The reason, of course, is quite obvious - his ball and patch combination was very weak & did not seal, which he admitted to

not realizing that many people were and are loading combinations that do seal, with no increase if a wad is used.

[Hungry Horse]

Dr. Fadala also cleaned his gun upside down, with hot water, he carried in a thermos bottle. He used double patches, and heaven know how many other wacked out things. So long story short I wouldn't relie information I got from good old Doc Sam.

  Hungry Horse

[bob in the woods]

Depth of groove, along with patch, and ball fit will play a part in what velocity you can obtain with a powder charge.  So will the lube you use. Looking at different combinations of .50 cal loads in a book I have, you could be anywhere from 1650 to 1750 FPS
Question is, why do you need to know  ?   There are a lot of other important factors in settling on a load for any given gun.

[hdsjr]

The Hodgdon Data Manual No.24 (1983) lists the following muzzle velocities with a 175 gr .490 round ball:

60 gr      1390 fps
70 gr      1554
80 gr      1729
90 gr      1872
100 gr    1988

As the previous posters said, a lot of variables influence actual individual results.

[OldMtnMan]

The Hodgdon chart is with Goex 2F. I'm thinking 75gr of Swiss 3F is equal to 90gr of the Goex 2F.

[OldMtnMan]

Depth of groove, along with patch, and ball fit will play a part in what velocity you can obtain with a powder charge.  So will the lube you use. Looking at different combinations of .50 cal loads in a book I have, you could be anywhere from 1650 to 1750 FPS
Question is, why do you need to know  ?   There are a lot of other important factors in settling on a load for any given gun.

Deep groove, 1-48, tight fit, mink oil lube.

As to why? Just curious. There's more to developing a hunting load than just accuracy. A target load will be all accuracy as a goal. A Hunting load needs to be accurate too, but I might give up a little accuracy to make sure the load has enough energy for a humane kill.

[hanshi]

My .50 has a 38" barrel and 70 grains of JBP gives 1700 fps.  75 grains should push it up a bit but let's say between 1700 fps and 1800 fps.  But with Swiss I have to guess at least 1800 fps.

[OldMtnMan]

Swiss 3F is pretty hot. I wanted 2F, but they were out. My other option was 1.5F, but I wasn't sure I wanted that. We'll see how it works out.

I only have a muley buck tag, but i'm hoping for a leftover cow elk tag. Love that cow meat.

[longcruise]

About 1700 fps with Swiss.  I have played quite a bit with chronographing and have found there can be differences with patch tightness, lot# of powder, etcetera.  Big variance between various manufacturers and  new tests could be very different.

Long story short, your first take on not paying much attention Is the practical approach, IMO. :-)

[OldMtnMan]

So true. If we were to go by PRB ballistics none of us would use one.

That round ball doesn't know it has lousy ballistics. It just does it's job and kills.

[Daryl]

I've heard you can read "The Sporting Rifle and it's Projectiles" online. It was written by Lieut. James Forsyth, M.A. 

It is well worth it & a good read, written in India in 1858, published in 1862/3.

It also contains important and pertinent paragraphs of other writers, like W.Greener, Samuel W. Baker and Major Shakespear, author of Wild Sports in India.

[OldMtnMan]

It was easy to find. I downloaded it in PDF from this site. Thanks.

https://archive.org/details/sportingriflean00forsgoog

[hanshi]

The tighter the patch, the higher the velocity.  Different lubes can also affect velocity.  I like and use rather tight loads for everything.  The only absolute requirement is that it MUST be safely seated with the wood, underbarrel rod.  I mostly use the ss range rod at the club but do seat a few with the wood rod periodically just to make sure.  Another thing I require is that the patch/lube/ball go down the bore time after time without having to wipe it with a patch.  A tight load makes this possible.

[Hungry Horse]

I would suspect that if all other components were equal, the twist rate of the barrel could make a difference in the feet per second numbers. I don't recall ever seeing anybody test this theory.

  Hungry Horse

[Daryl]

Faster twists or rifling itself reducing the velocity was thought to be entirely true & and was often written about, also by Forsyth - back in the 1800's.  We did test this to some extent many years

ago.  A quick test using a .62 42" smoothbore VS 34" .62 cal. Hawken - with patched .615" in the Hawken and patched .600" in the smoothbore.  With identical loads, their velocities were

extremely close - even to the point, barrel length showed very little favour was noticed from the smoothbore.  IIRC- some powder charges showed favour to the shorter rifle, while others showed

favour to the longer smoothbore.  The differences in patching and different guns, probably produces more difference than whether the twist is fast, slow or no rifling at all.  They were so close, as

to have no appreciable value.

One might think the smooth bore would produce higher speeds due to less friction to the patch and ball & - that seems logical.  On the other hand, the rifling, in it's resistance to the patched ball,

actually causes an increase in pressure for a given load shown in more efficient burning of the charge and that increase in pressure also increases the velocity - or more appropriately here,

perhaps this slight increase simply causes the rifle to match the velocity that of the lesser resistance of the smooth bore.

[Brian cox]

I hope this helps - From Lyman Black Powder Handbook 1975

[OldMtnMan]

It does. Thanks.

The only thing that's hard to figure is how much more will the Swiss be over Goex. I've seen as much as 200fps from those who chrono'd it.

Not that this is so important. Just something to yak about.

[Brian cox]

paste image host
Glad it helped - some added fun - same source Lyman Blackpowder Handbook 1975