Forsythe rifled 50 cal load question

[axelp]

So I am soon to have an Isaac Haines 50 cal rifle in flint, but the barrel rifling is "forsythe" style rifling. I will be working up a load and wanted to ask the experts here where I might want to begin with a load. 38" long b weight swamped. 1:80 or 90 twist (I think--not sure) and shallow .008" rifling.

I'd like to discuss ball & patch size, and also recommended powder amounts-- at least a ballpark to begin with.

This type of rifling requires more powder, larger ball and thinner patching... am I correct?

thanks  Ken

[Dphariss]

While its certainly your decision I would not go that slow with a 50 there is no need. Ball weights under about 300 grains don't seem to care much.
Forsythe was shooting 14 and larger bore rifles. These are far different than shooting even 58 caliber rifles.
A 15 gauge ball weighs 466 grains if a true 15. My "bore rifle" shoots a 437 gr (one ounce) ball with an 80" twist its apples and oranges compared to the 50-58.

In the 1820-1860 period British were generally using one turn in the barrel length. They also thought the bigger the ball the faster the twist needed. This is of course backwards from actual fact and this had been proven in tests leading to the adoption of the 20 bore Baker rifle in 1800 by the British Army.
With a barrel in the 26 to 30" range this was too fast for the rotational inertia of a large ball with a load in the 1500-1600 fps range and the patch would blow. As an aside this was why the "belted ball" system was adopted. It was a failed technology that required a lot of hoop jumping to allow the fast twist to be used with large diameter balls and fast twists.

Forsythe advocated a much slower twist. He liked 8 ft 6 in for a 14 bore or even slower 10 or even 12ft.
This allowed heavy charges needed in Africa and India. He used a 15 bore ball in the 14 bore (69 cal) and a "rather substantial patch".

The GM 50 caliber twist of 70 inches with their narrow lands is very Forsythe like for the bore size.
Since I have owned 48" twist 50 calibers (3) and they all would shoot all the powder anyone would need, that John Baird and TK Dawson tested an original 48 twist rifle to 130 gr of FF with very good accuracy I feel that twists slower than 48 are simply not needed for 50 calibers.
But I like GM barrels and the 70 twist shoots very well. So while I like the 48 twist I see no need to special order 48 twist barrels.

Forsythe also believed that the slow twist gave higher velocity. I am not sure this is true. The British used to intentionally rough bore shotguns for a few inched at the breech to increase velocity. I ran into the same thing with a rough rifle barrel. It was rough for about 10" at the breech and shot 100 fps+ higher than a smooth barrel of the same length with the same powder and ball. Though the rough bore DID have 96 twist. Near as I can tell without shooting them side by side Daryls 69 with a 72 twist is ball park for my 16 bore (67 cal bore) with similar powder/ball weight ratios.

This said I would be very interested in any information you might glean from a slow twist 50. Love those experiments.
One advantage would be that the slow twist might shoot small shot surprisingly well. So if you do get a slow twist 50 caliber try shot in it. I keep meaning to shoot some 7 1/2 shot though the 16 bore but have not gotten around to it.
A friend has a straight rifle barrel on order.
Dan

[axelp]

I know its a departure, and I too am looking forward to seeing what kind of results I come up with....Just to clarify---I was not asking whether the barrel was a good idea or not. I already committed myself to try it. What I was asking y'all was a suggested starting point as far as ball size, patch, and powder.

should I try .490 or .495? or? and a .010 patch? I figure I would start with 65 gr of FFF and go up?

thanks

K

[northmn]

Teh 64 BAker rifle had 1-120 twist and shot fairly well.  A 1/80 is really not all that different from my 50 with a 1-72. The old theories were that slower twiss gave better accuracy with heavier loads, whcih has been argued ad nauseum on this site.  Some also liked them as they may seem to be affected by fouling less.  As the Baker was a military rifle, that may have been an issue. I would think that you could start out with standard loads as I used in my 1-72 inch twist.  I did fair with 50 grains 3f at close range and 80 at longer ranges.  I would bet that your twists 1-80 or 1-90 would be close to that.  As to patch/ball size.  I used to shoot Numrich barrels which had a shallower rilfling, probly a little less than you 008 and found that they did best with a little larger ball and thinner patching.  Cotton muslin made a very good thinner patch and was very tough.  Most rifling today is over 010.  All barrels are individuals and unless you know the bore size no real recommendations can be made conserning patching.  If a 495 ball rolls down the muzzle it will work as would a 500.

DP

[Daryl]

I think Ken's main reason for the slow, shallow grooves, is to shoot the ITX balls just as accurately as lead.  With the ITX - I'd use as thick a patch as I could and still load it.  You might have to use a wad to prevent blow-by, but that was why the shallow rifling, for a tight fit without cutting, to the bottom of the grooves.

For a normal soft lead ball, I'd probably use a .495", but a .490" pure lead ball with an .018" to .022" patch should work just fine, giving a minimum of .005" compression on the bottom of the grooves.  That would be a minimum load, as I've found .005" has been required to prevent cutting and gas cutting - along with accuracy.  Due to the shallow rlfing and slow twist, .005" compression (or less, perhaps) might be all that's necessary, even with heavy loads.

As to powder charges, shoot what gives the best accuracy, however,  I can say with complete conviction, that, that barrel will shoot more accurately with any increase in powder you are willing to pour down the tube- to perhaps 130gr. 2F or maybe even more.  Note that as the powder charge goes up, so does the pressure.  Increased pressure demands increased compression of the patch and lead in the bottom of the grooves - ie; higher the load, the tighter the ball/patch combination has to be.

 In normal faster twist and deeper grooved barrels, if you don't want to use a tight combination, there will be a ceiling where any more powder will cause gas cutting - at that temperature and atmospheric condition.  This same condition may happen in your new barrel, Ken, but to a lesser degree.  Ie: the ceiling might be 80gr. with one combination, and 120gr. with another.  Note I said at that temperature.  This is more important than we realize and I've proved to myself it happens more often that we realize.  A load that works in spring or fall, can fail in 90F or 100F temps.  It happened in my .69 as well as my .40, and I usually shoot tighter combinations than most other shooters to start with. 

[axelp]

Thanks to all. Yes, Daryl is correct.

I'd first like to try and work up the best load for lead roundball, and after I get her dialed in, THEN I will do the same for ITX lead-free roundball. I probably wont be getting the rifle for another few weeks-- It is a Chamber's Issaac Haines kit, with a specially made Rice Barrel (thanks Jason). Brent Gurtek of Duluth is building it for me (because I am "gunbuilding impaired")

By the way, I am using ITX for the local deer season right now-- in a standard rifled 50 cal flinter, and am having pretty good results accuracy -wise. No deer yet, but I killed a pine squirrel that was pestering me--I hit it where I aimed. And I killed a pinecone and a dead snag at 25 yards. My previous target work with ITX was plenty adequate at 50-60yards...  I am using my EXACT load combo that I use for lead, but I used the .487 ITX ball. It loads great with no patch cutting (in this rifle anyway) And it seems to be equally as accurate for this particular gun.

I did not think about trying shot out of the new IHaines gun..... hmmmmmmmmmmmmmmmm.

[Dphariss]

Thanks to all. Yes, Daryl is correct.

I'd first like to try and work up the best load for lead roundball, and after I get her dialed in, THEN I will do the same for ITX lead-free roundball. I probably wont be getting the rifle for another few weeks-- It is a Chamber's Issaac Haines kit, with a specially made Rice Barrel (thanks Jason). Brent Gurtek of Duluth is building it for me (because I am "gunbuilding impaired")

By the way, I am using ITX for the local deer season right now-- in a standard rifled 50 cal flinter, and am having pretty good results accuracy -wise. No deer yet, but I killed a pine squirrel that was pestering me--I hit it where I aimed. And I killed a pinecone and a dead snag at 25 yards. My previous target work with ITX was plenty adequate at 50-60yards...  I am using my EXACT load combo that I use for lead, but I used the .487 ITX ball. It loads great with no patch cutting (in this rifle anyway) And it seems to be equally as accurate for this particular gun.

I did not think about trying shot out of the new IHaines gun..... hmmmmmmmmmmmmmmmm.

I sometime forget that people in some areas are afflicted with oppressive gov't regulations.
I shoot a ball about .008" under bore in the 16 bore and a .018 patch of cotton ticking.
When I shoot hardened lead, WW I shoot a thinner patch of linen .012-.014. Linen usually requires as thinner patch since its tougher and less compressible than cotton.
This rifle has eight .008 deep grooves and they are very wide. It has yet to blow a patch with any thing I have shot through it but I don't play with patching much having pretty well worked this out years ago.
In a 50 I would go with a patch that let me load the ball and 75-90 grains of FFF to start. But it could shoot well with far more powder. In my experience its not the twist so much as the particular barrels idiosyncrasy that determines the powder charge.
I was shooting ticking lubed with water soluble oil that was allowed to dry and this would blow patches with .495 ball and the heavy ticking. This was a 70 twist GM barrel. The cure was a patch under the ball. Or to stop using water soluble oil. I don't know why this caused this unless it was friction in the bore.

Have fun with the slow twist 50 and by all means keep us posted.
I have read that some original rifles with "straight" rifling were actually very slow twisted when carefully examined. But this is second "knowledge" at best.

Dan

[axelp]

Thanks Dan, all this is great direction---as usual. I will keep everyone updated with what I find out.

YES, sadly I live in the northern most area of this abomidable CA lead ban. I can drive a couple miles, and shoot lead to my hearts content, or I can go in the other direction and cannot use lead while hunting. I can still target shoot with lead and even shoot lead shot when hunting upland game and squirrels here though...

Thankfully, this ITX stuff seems to be a workable option... I figure it is the first of many options to come if this lead ban spreads...hope it doesn't though!

Ken

[beleg2]

Hi,
for those interested in Forsyth book:
http://www.archive.org/stream/sportingriflean00forsgoog#page/n16/mode/1up

It can be read inlone.
I also can send you my own "edition" for printing in A4 paper.

Very interesting reading, one of the best old book on guns.

Martin

[Dphariss]

Hi,
for those interested in Forsyth book:
http://www.archive.org/stream/sportingriflean00forsgoog#page/n16/mode/1up

It can be read inlone.
I also can send you my own "edition" for printing in A4 paper.

Very interesting reading, one of the best old book on guns.

Martin

Seems like google books has it online as well and a number of Sir Samuel Baker's books and who knows what else. They have the very interesting W. Greeners "The Gun" from 1830s but its hard to get to since W.W. Greener's "The Gun and Its Development" keeps coming up first.

Many can be downloaded.

Dan

[beleg2]

Dan,
They have many famous books of old experts like Hawker, Walsh (Stonehenge), three different editions if Gun and its development, old W Greener book, Roosevelt, etc.
Martin