Hi , I am currently making a ml rifle and am now in the proccess of rifling the barrel the rifling pattern I have chosen is the same (as near as I can make it )as Harry Popes design.. I have figured that it is best suited to a flat based conical and the projetile I have chosen will be 1inch long driven about 1100 foot per seconds with a 1in 32inch twist ,40 cal bore .. would I be able to use a prb in the same gun .. Should I use a paper patch or just lube the conical.. :hmm:
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PreserveFreedom
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I have always used lube with my conicals with good results. The only downside that I see to lube is that a round left in the tube could get your powder moist. A wad between the charge and projectile could solve that problem though.
I'm not an authority on the subject and don't know if this will be of any help, but your question makes me think of T/C Arms standard Hawken / Renegade barrels which have fairly shallow grooves to be able to shoot conicals, yet still shoot PRBs with very good accuracy...their configuration in .45/.50.54cals is .006" x 1:48" twist.kiwi2 said:
in my experience ive never seen a PRB shoot consistently from a fast twist barrel. but ive only seen a handful of people, including me, try it. ive had very good results with lubed conicals, my zouave loves bore butter and wad cutters. i have never tried paper patched bullets. although i have been using pillow tick patches on .458 bullets in a fast twist .50cal for years and its deadly.
zimmerstutzen
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If you are really copying Pope's style, the lands are extremely narrow, almost like rails. The paper patching might be very tough on the narrow lands. I don't think Pope used paper patched bullets in his prime.
The shape of pope's grooves are designed to help grip the bullet. (shallower in the middle than at the edges) I have a round ball barrel with a round ball twist that has a modified Pope style rifling, with narrow lands. It shoots exceptionally well.
Generally round ball rifling can be a fast twist, for instance in pistol barrels, but the more depth is required to grip the small area of the PRB that slides on the bore. A conical has far more bearing surface against the bore.
The shape of pope's grooves are designed to help grip the bullet. (shallower in the middle than at the edges) I have a round ball barrel with a round ball twist that has a modified Pope style rifling, with narrow lands. It shoots exceptionally well.
Generally round ball rifling can be a fast twist, for instance in pistol barrels, but the more depth is required to grip the small area of the PRB that slides on the bore. A conical has far more bearing surface against the bore.
The rifling for a paper patched bullet is very shallow to minimize cutting of the paper and is unlikely to work well with a patched roundball.
The rifling in my .40 caliber Schutzen is only about .0015 deep and it shoots paper patched bullets very well.
It shoots patched roundballs very poorly even with VERY tight ball/patch thickness combination's.
As roundball mentioned, TC (and others) uses a compromise groove depth. (Dixie Gunworks says it is .005 deep in the Thompson Center .50 cal. Hawken.)
This works with patched balls if the ball/patch thickness combination is very tight.
Shallower grooves will probably not work well for a patched ball.
The rifling in my .40 caliber Schutzen is only about .0015 deep and it shoots paper patched bullets very well.
It shoots patched roundballs very poorly even with VERY tight ball/patch thickness combination's.
As roundball mentioned, TC (and others) uses a compromise groove depth. (Dixie Gunworks says it is .005 deep in the Thompson Center .50 cal. Hawken.)
This works with patched balls if the ball/patch thickness combination is very tight.
Shallower grooves will probably not work well for a patched ball.
Paul , thanks for the heads up ,I had another look at my calcs and see that I quoted the work I had done on a .45 cal barrel for a friend :shake: , a one in 35 inch twist would have seriously made me seem a right idiot :redface: and the 35 number was fixed in my head , just glad I am still putting together the rifling head .. Yes I will be shooting conicals but not modern by any stretch of imagination ..
Paul , I have run the numbers over my internal ballistics programme and I would need to be shooting a projectile a bit over 1.5 inches long at around 1100 fps to need a 1in 16 twist however I want to use a 1inch long projectile ,so the figures come out at 1 in 25 inches , but since I have already made a muck up in the calc departmnet I will check again just before I start cutting grooves to make sure that between us we get it right thanks appreciate your remarks .. :v
paulvallandigham
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My reference Chart on the Greenhill Formula confirms you 1:25" ROT for a .411 cal. bullet that is 1 inch long.
I think more important to you is groove depth, and groove width, as discussed above. I don't think you can have your "Cake and Eat it, too!"
Shallow grooves will work better shooting conicals. Deeper grooves are needed to shoot PRB accurately.
Narrow lands may work with lead bullets that have grease grooves and are lubed, while wider lands may work better if you paper patch the bullets.
There is no doubt by ME that protecting the base of any cast bullet with some kind of filler or wad that seals which ever groove depth you use will produce greater accuracy. My father began experimenting with base wads( in cartridge casings, using black powder, and smokeless powder loads) when I was a kid, helping him reload, and then spotting his targets at the range for him. Since I became involved with BP shooting myself, I have spent way too much time trying to find some "happy medium" where the same ROT and rifling will shoot both conicals, and PRB well.
I don't think the beast exists, but I am talking Target accuracy now, not hunting accuracy. You will get lots of opinions here-- along with a few harsh arguments--- and elsewhere, unless you define what kind of Accuracy you are looking for with both kinds of projectiles. The Chunk Gun shooters in this Country are going back and forth between using a .40 caliber rifle, and a .45 caliber rifle in their sport, but that calls for PRB, and targets are shot at 60 yards. You gets all kinds of " discussions and comments" in those circles about ROT, velocity, diameter of ball, patch thickness, lube, or whether to shoot the Teflon patching, etc.
The only other BP target shooting group that has more heated arguments seems to be the Black Powder Cartridge Metallic Silhouette Shooting Association members, where those longer conicals( Longer than 1 inch) are used. Steve Garbe, and Mike Venturino have published a Black Powder Cartridge reloading manual, that is chock full of information on what works, and what doesn't( including base wads). If you are looking for the optimum ROT for any conical I would recommend spending the money to buy that book, as it gives sound advice and some data that can also be used in MLing targets rifles. For instance, ( and the reason this came to mind to suggest to you) many of the BPMSSA members are using the .40-65 cartridge using bullets, and some are using Paper patched bullets. The Garbe manual has some good loading data for the .40-65, which may help you in developing a load for your .40 cal. MLing Target rifle.
Good luck with the project, and keep us posted, Please. :hatsoff: :hatsoff:
I think more important to you is groove depth, and groove width, as discussed above. I don't think you can have your "Cake and Eat it, too!"
Shallow grooves will work better shooting conicals. Deeper grooves are needed to shoot PRB accurately.
Narrow lands may work with lead bullets that have grease grooves and are lubed, while wider lands may work better if you paper patch the bullets.
There is no doubt by ME that protecting the base of any cast bullet with some kind of filler or wad that seals which ever groove depth you use will produce greater accuracy. My father began experimenting with base wads( in cartridge casings, using black powder, and smokeless powder loads) when I was a kid, helping him reload, and then spotting his targets at the range for him. Since I became involved with BP shooting myself, I have spent way too much time trying to find some "happy medium" where the same ROT and rifling will shoot both conicals, and PRB well.
I don't think the beast exists, but I am talking Target accuracy now, not hunting accuracy. You will get lots of opinions here-- along with a few harsh arguments--- and elsewhere, unless you define what kind of Accuracy you are looking for with both kinds of projectiles. The Chunk Gun shooters in this Country are going back and forth between using a .40 caliber rifle, and a .45 caliber rifle in their sport, but that calls for PRB, and targets are shot at 60 yards. You gets all kinds of " discussions and comments" in those circles about ROT, velocity, diameter of ball, patch thickness, lube, or whether to shoot the Teflon patching, etc.
The only other BP target shooting group that has more heated arguments seems to be the Black Powder Cartridge Metallic Silhouette Shooting Association members, where those longer conicals( Longer than 1 inch) are used. Steve Garbe, and Mike Venturino have published a Black Powder Cartridge reloading manual, that is chock full of information on what works, and what doesn't( including base wads). If you are looking for the optimum ROT for any conical I would recommend spending the money to buy that book, as it gives sound advice and some data that can also be used in MLing targets rifles. For instance, ( and the reason this came to mind to suggest to you) many of the BPMSSA members are using the .40-65 cartridge using bullets, and some are using Paper patched bullets. The Garbe manual has some good loading data for the .40-65, which may help you in developing a load for your .40 cal. MLing Target rifle.
Good luck with the project, and keep us posted, Please. :hatsoff: :hatsoff:
Kiwi....The .40 cal.Pedersoli Gibbs target muzzleloader has a 1:16 twist. My 40-65 Ctg. rifles have 1:16 twist. My 40-70 ctg. rifle has a 1:14.5 twist. The 14 1/2 twist will easily stabilize any bullet from 440 grains on down...repeat...easily. The 1:16 twist will easily stabilize anything from 400 grains on down. On the other hand, a 1:25 twist will ONLY stabilize the small bullets. You'll never be able to shoot the big bullets needed for accurate target work out to 600 yds. Why limit yourself? G'day mate! Paul
paulvallandigham
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PaulLab has reminded me of that "something else" you may not know. If you are going to be a Target Shooter, and want that "Big Barrel", then you should be considering a faster ROT, as he suggests, so that you can shoot targets out to 500 yds, with Longer Heavier bullets.
Because of the popularity of the BPCSSA and those .40 caliber breechloaders, there are also lots of barrel makers who make those barrels. They can be had in either Octagon, or round.
You can shoot PRBs out of these guns, but it requires an almost bore diameter, and sometimes, almost groove diameter( on the shallow grooved barrels) with a tight, thin patch, and a over powder wad, or fillers, to provide a "firewall" to protect the patch from burning in the barrel, to get accuracy. However, you normally don't expect to get anywhere near the velocity with that PRB that the deep groove rifled barrels can give you, and you will need a mallet and your short starter to start those balls into your barrel.
OH, I suspect that PaulLab would agree that the Faster ROT will stabilize the shorter, lighter bullets well, but the slower ROTS won't stabilize the Longer, heavier bullets as well. If you want flexibility in a rifle, using the faster ROT makes a wiser choice.
MY Springfield Trapdoor, .45-70 has a 1:22 ROT barrel. It does okay with the 405 and 500 grain lead bullets the military uses. However, it does not stabilize the longer, heavier bullets s well, as a faster ROT, such as a 1:18, 1:16, or 1:14, particularly when the velocities are increased.
My father's Springfield had a barrel that was so badly overbore in diameter that my brother had a new liner put in the barrel. The Gunsmith who did the work suggested that he use a 1:18 ROT so that it would stabilize the 530 grain "Postel" bullets, now commonly being used in long range target shooting. It Stabilized a 350 grain shorter bullet well, too.
Because of the popularity of the BPCSSA and those .40 caliber breechloaders, there are also lots of barrel makers who make those barrels. They can be had in either Octagon, or round.
You can shoot PRBs out of these guns, but it requires an almost bore diameter, and sometimes, almost groove diameter( on the shallow grooved barrels) with a tight, thin patch, and a over powder wad, or fillers, to provide a "firewall" to protect the patch from burning in the barrel, to get accuracy. However, you normally don't expect to get anywhere near the velocity with that PRB that the deep groove rifled barrels can give you, and you will need a mallet and your short starter to start those balls into your barrel.
OH, I suspect that PaulLab would agree that the Faster ROT will stabilize the shorter, lighter bullets well, but the slower ROTS won't stabilize the Longer, heavier bullets as well. If you want flexibility in a rifle, using the faster ROT makes a wiser choice.
MY Springfield Trapdoor, .45-70 has a 1:22 ROT barrel. It does okay with the 405 and 500 grain lead bullets the military uses. However, it does not stabilize the longer, heavier bullets s well, as a faster ROT, such as a 1:18, 1:16, or 1:14, particularly when the velocities are increased.
My father's Springfield had a barrel that was so badly overbore in diameter that my brother had a new liner put in the barrel. The Gunsmith who did the work suggested that he use a 1:18 ROT so that it would stabilize the 530 grain "Postel" bullets, now commonly being used in long range target shooting. It Stabilized a 350 grain shorter bullet well, too.
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Mine is a .40 bore with .411 groove and 16" twist.
It works great just as long as the bullet is long enough.
The barrel is intentionally made with narrow lands to use pre-engraved bullets. The engraving die is made from a piece of the barrel.
It works great just as long as the bullet is long enough.
The barrel is intentionally made with narrow lands to use pre-engraved bullets. The engraving die is made from a piece of the barrel.
paulvallandigham
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After using the Greenhill formula "Chart" I have for a number of years, and different calibers, I have decided that the formula tends to give you the "SLOWEST ROT for your bullet, and not necessarily the Best choice of ROT for that particular caliber. Erring on the side of a faster ROT doesn't seem to cause many problems with conicals, and accuracy.
Because of the smaller bearing surface of any caliber RB, it doesn't take much spin to stabilize a round ball. Slower ROTs seem to be more forgiving to changes in powder charges, and MV variations, as far as Point of Impact when shooting at the yardages customary for shooting RBs at anything- target or game. That seems to be the ONLY Justification for using the VERY SLOW ROTs for RB barrels. But, that's not a bad reason, IMHO. :thumbsup: :thumbsup:
Because of the smaller bearing surface of any caliber RB, it doesn't take much spin to stabilize a round ball. Slower ROTs seem to be more forgiving to changes in powder charges, and MV variations, as far as Point of Impact when shooting at the yardages customary for shooting RBs at anything- target or game. That seems to be the ONLY Justification for using the VERY SLOW ROTs for RB barrels. But, that's not a bad reason, IMHO. :thumbsup: :thumbsup:
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