Depth Of Rifling

[FishDFly]

From reading many of the past posts I understand the basic differences, advantages and disadvantages to shallow versus deep rifling.

What I was wondering, will deep cut rifling tend to cut patches more and for a longer period of time since there is more room for the patch to fit into compared to shallow cut rifling?

Thanks

RDE

 

[JOHN L. HINNANT]

Good Afternoon Richard,

In my 53 years of shooting muzzle loaders, I have never seen any evidence that deep cut rifling cuts patches any more or less than shallow cut rifling.

The finished quality of the barrel and the muzzle crown have more to do with the cutting than the depth of the rifling.

The deep cut (.010"- .012") rifling is single tool cut or broach-cut. This tends to leave a sharp edge on the top edges of the lands. Most of the better barrel makers use a lap to remove this sharpness.

Noticed that you mentioned the TMLRA at Brady, Texas in one of your post. Were you there this past week (October 5 - 8) or last June?

Best regards and good shooting,

John L. Hinnant

If you are not an NRA or NMLRA Member, why not? I am carrying your load.

 

[szihn]

There are more issues to address than just depth.

The geometry of the rifling and the patch material have to be considered.

There is as much mis-information about barrel making as there is information.

One of the things that's written in more articles than we can count is the mith that the twist is most important. I have made many barrels in the past and I can tell you that the twist is less important to round ball barrels than any other factor.

I have made 1-18 twist barrels with 3 to 1 grooves and they shot outstanding groups. The fast twist doesn't harm accuracy at all with balls, but it does foul very fast, and very badly.
I have done 1-1 square cut rifling in 1-60 twist and found that the barrels were not at all forgiving. If I cut 3-1 groves with about a 7 degree angle on the sides of my cutters, the barrels will shoot very tight groups. I lap my barrels to polish and remove the sharp edges on the top of the lands and they shoot both light or heavy charges well.
I believe that the correct geometry is the first and most important thing to consider, then the depth should be at least .008" and not more then .014" Lastly, the twist should not be slower then 1-40 for ball guns. Faster is just as accurate, but no more accurate, and the fouling is worse.

If you go very slow in your twist you have to use large powder charges to get the revolutions per second up to a point where the ball will be compleatly stable. The old Forsyth type is very good, and for hunting rifles it can be twisted long, (even out to one turn in 9 feet) but for an all around rifle a faster twist is better. I like to cut them no slower than 1-66 for bores up to .62. In my 8 bore and 4 bore rifles I can go longer. If the bore is well polishes, and if you use a good lube, fouling in a 1-66 is not a problem.
The lands in the barrel will work best if they grip the patch tightly, and allow the obturation of the ball to grip it when the powder fires. If the lands are too wide (in other words, the grooves are too narrow) the patch is limited in how easily it can go into the groves, and it loads hard. Any fouling then only makes reloading harder.

Narrow groves in a barrel collect and hold fouling. Wide lands collect less, and wipe out easily when the next patched ball is loaded.
With all that said, the overall quality of the bore is VERY important. It should shine and have NO curcular drill or reamer marks on the top of the lands. The grooves can have some striations going lenght ways, but even thjose should shine with the polish.
Hope all that helps.

Steve Zihn

 

[davy]

Hey Steve have we seen any photos of your 8 and 4 bore guns? I sure would like too! :grin:

Davy

 

[JOHN L. HINNANT]

Good Afternoon Steve Zihn,

A most excellant post on rifling for the PRB. Not that it really matters, but I am in complete aggreement with you on all points.

You mentioned that a 1-66" is the slowest pitch you like to cut up to 62 calibes. Do you have other twist preferences for othe calibers and would you share that information with us? And how you determined why those twist are preferable.

Best regards and good shooting?

John L. Hinnant

 

[szihn]

Hello John L.

When I was doing a lot of barrel making I experamented with a lot of different twists. In general we must remember that movment of mass = momentum.
So, when you have a 32 caliber ball rotating it has a LOT less mass then a 62, which has a LOT less mass than an 8 bore and so on and so forth.
Therefore a smaller ball must twist faster to overcome exterior forces. The gyroscopic momentum of a .600" ball ( which is 1.884 in circumferece) X pi is much greater than a 310" ball (which has a circumferece of .973)
So as you can see the rotation of the 310 is going to have to be roughly double that of the 600 to acheave the same gyrospic stability.
In the "real world" you will see that a 1-66 is fine for a 62 cal, but a 32 cal should be about 1-36 to 1-40. Remember, you can twist them faster with no ill effect at all, except fouling, so these are all just guidelines
I rifle all my own pistol barrels but I seldom make a rifles rifle barrel anymore. I can buy a very good one for a lot less than I can make one.
I have a lathe I drill and rough ream with, but all my rinish reaming, rifling, bore polishing and all the exterior is done by hand. the last 44" barrel I made took me 68 hours. I can buy a good one for about $220. So you could say I worked for $3,23 an hour to make that barrel. Not worth it!
I did a lot of them when I wanted to do the work so I could learn how, and so I could have a few "bragging guns". I will still make 100% hand made guns if they are ordered, but the price of such a gun is over that which most people want to pay. I love such work, but I can't make a living at it without finding a lot of rich people who want such work, and most of the shooters I know are just working men like myself.
But this kind of info is what keeps our sport interesting, and I am always willing to share it with anyone that asks.
But...........that's all a "rabbit trail" As far as what I would rifle now, if I were to make some barrels:
1 in 40 for 32 to 40 cal
1 in 48 for 45 to 50 cal
1 in 56 for 54 to 58 cal
1 in 60 -66 for 62 and 66 cal
1-72 for 12 and 10 bore
1-80 for 8 bore
1-96 for 4 boreNone of these are written in a tablit of stone and passed down from the very hand of God. They can be plus or minus 6" either way up to 66 cal and plus or minus 12 inches for 72 cal and over, and you'd never know the difference if the bore geometry is correct.

As for the pics...here are a few of some 8 bores I made.
Stupidly, I didn't photograph the 4 bore rifles I have made

 

[davy]

Very nice Steve .. thanx for sharing those photos.

Glutton for punishment or not ... I have a perverse hankering to shoot one of those big bad boys at least once (once would probably be enuff! :shocked2: ) I'll probably live to regret it if I do .. but what can I say? :hmm: :thumbsup:

Davy

 

[renovato]

Davy, me too! I've always had a love of shoulder pounding guns. Back when Tennessee Guns had those 4 guage shotguns I almost bought one just cuz. A 4 or 8 guage front stuffer is almost too much to resist.

Steve, as always, your craftsmanship never fails to impress me! Thanks for the pics. Now I'm drooling!

 

[FishDFly]

John L.

Thanks for the information.

I sent you a PM.

Thanks

RDE

 

[roundball]

In contrast to all the "old fashioned absolutes" repeated over and over down through the decades, your findings and experience explains why my personal experience shooting .45/.50/.54cal PRBs in 1:48" twists has always been outstanding.
:thumbsup:

In fact, my 'signature line' on all other ML forums is:

"Flintlocks.......The Real Deal"
(PS: Claims that 1:48" twists don't shoot round balls accurately are old wives tales)

 

[FishDFly]

Steve Z.

Thanks for the information and education, I learned a lot.

I cut and pasted your information and saved it where I can retireve it when needed. It's to valuable not to keep it.

Thanks

RDE

 

[szihn]

Well guys, I can tell you that the 8 bore is the nicest BIG gun you'll ever fire. The recoil is about like a 458 Winchester, but about 1/2 the speed. I have fired them up to 32 rounds in an afternoon, and had no pain of discomfort at all. I build my single barreled 8 bores at about 9 pounds and I have put murcury recoil reducers in them when requested. A light weight 300 magnum is much worce.
Now a 4 bore on the other hand..........
They are the guns from hell. I am a short man, (5'6") but I have not been called little very many times. (195 lbs) But when I fire a 4 bore it spins me in a half circle and backs me up about 2 feet-- and it's quite difficult to hold on to. I would call the recoil "about as fast as a 458 and about 3 times more." I build them but I hate fireing them.
I have a double 62 caliber bullet rifle, an 8 bore double ball rifle and an 8 bore single ball rifle coming up in the next year. I also have the parts for anouther 4 bore ball rifle. I will make them and put them out at Safari Club for sales in the next year of 2 if I get time. Looking for someone to sight in the 4 bore. No experience (or intelligence) necessary. :grin:

 

[Blizzard of '93]

Double ball rifle? You mean rifle specifically made to fire 2 PRB's? Could you provide some specifics as to twist rate and rifling depth? Also I've wondered about something along the lines of Marlin's 'microgroove' rifling applied to a BP gun. No doubt it would foul faster but a dry patch between shots anyway, what would it matter. Marlins are noted for accuracy, from .22 to 35 rem. I have a Marlin .22 that shoots as good as I can hold it, as good as high dollar rifles. That is with good ammo to begin with.

 

[silverfox]

blizzard: I think what he means is a double barrel rifle made to shoot PRB. Not a rifle to shoot 2 PRBs at a time. Even then and 8 would be a very large gun to lug around.
Fox :thumbsup:

 

[Slamfire]

Yore description of the 4 bore's recoil, parallels Sir Samuel Baker's testimony about "Baby". He said it made his nose bleed and his head ache for 2 days. Of course, he wasn't usin' no dinky round ball but a 8 oz. conical! :shocked2: Apparently on the theory that an angry elephant could hurt him worse than the rifle. :v

 

[szihn]

No. No.
I mean a double barreled rifle. Left and right.

Sorry. I should have been more clear. :redface:

 

[szihn]

Getting hammered by an angry elephant would be worce than firing a 4 bore with a heavy bullet.
(but not much worce!)
:grin:

 

[Stumpkiller]

Yippiee Skippie! That is some rifle!

I thought long and hard and decided on 1:66" for my .54 flinter as I load moderately. The very slow twists like 1:80" seem to prefer a stouter load. My .54 percussion is a tack driver with 1:48" rifling and light (mid 40 gr FFg) loads.

I do believe the deeper radius groove rifling holds fouling better and allows less wiping, but is no more or less accurate than a shallow groove if wiped between shots. You still have to find the right ball diameter and patch thickness to suit that particular rifle regardless.

 

[Slamfire]

Getting hammered by an angry elephant would be worce than firing a 4 bore with a heavy bullet.
(but not much worce!)
:grin:

I reckon it'd be about a draw t'wixt the rifle and one of them wide rhinopotamooses. :rotf:

 

[Brutus]

Looking for someone to sight in the 4 bore. No experience (or intelligence) necessary. :grin:

I got more brawn than brains, I'll give 'er a shot, or three...