Progress on rifling machine and rifled choke tube!

[Col4570]

I have rifled barrels in the past,a good rifling bar can be made from 3/16th" x 1" mild steel bar twisted and run between two rollers.For the rifling head a cutter must have no top rake but the end rake should be the radious of your grindstone,exactly as you would when sharpening a lathe tool.My rifling heads are Steel with an adjusting screw that pushes a wedge that adjusts the height of the cutter.My last Rifling I used my whitworth rifle Barrel (one turn in Twenty inches),as follows,Make a rod with the rifling head at on end,Make some saw cuts at the other end,Fit a wad in the barrel,Stand the barrel and rod upright,heat the barrel until water sizzles on it (Spit),pour in molten Hard Lead.Using plenty of oil pull and psh iside the new smooth bored Barrel until it stops cutting then index round one whitworth flat and repeat until all grooves are cut.pull the cutter out and adjust 1/4 turn of the screw and repeat the cutting sequence until the required depth.

[Ballistics in Scotland]

BIS:

It occurs to me that you live in the land of Paradox guns and bore guns. Do you have access to any? I am really curious about twist rates especially for the Paradox guns.

If you could get that info I would be forever in your debt.

Longbow

I don't have access to any, and they are quite uncommon nowadays. They would be subject to the same licensing as rifles, rather than the type for shotguns - for a along time none whatever, and even now relatively easy to get. Add the fact that they have very little use for anything in the UK, and I would suspect that many were bored out as ordinary shotguns, just as many rook rifles unfortunately were.

You have to remember that "Paradox" was a Holland and Holland trademark for the guns they made under Col. Fosbery's patent of1885. It was much copied minus the name - possibly early on, for I don't know how much of it was protected by the patent, and certainly for a brief period after the patent expired. Names like "Jungle gun" were often used, and I wouldn't put it past the Belgians to find the odd Panados or Paradoz on Skid Row to rent out his name for what were, usually, firearms of quite reasonable quality. All of these were very much the gun of the casual hunter - farmers, travellers, even missionaries - and their period of real popularity wasn't long. Smokeless powder and jacketed bullets were almost contemporary with the Fosbery patent, and events forced millions into intimate acquaintance with the bolt-action rifles which became very cheap on the surplus market.

WW Greener writes that the original Paradox had a "sharp spiral", which 36in. would be for the types of projectile intended, and says the shot pattern was better than a cylinder bore. The latter claim surely means tighter, and might not be greatly significant to many users, but it encourages me to believe Wikipedia when they say only the last two inches were rifled. If the diameter of a choke extends further than that, it will no longer tighten the pattern, as the inward movement of shot, which accomplishes this, will have ceased.

In a lead-bullet rifle there is usually some slight slippage in the rifling as the bullet starts moving, but for most of its path the rotation closely matches that of the rifling. This is not necessarily the case when it hits the rifling at speed. It is possible that the "sharp" spiral is the one that Col. Fosbery found would impart the minimum rotation a ball or short bullet needed.

Under other circumstances loosening of the bullet in the rifling is considered a receipe for disaster. But in this case loosening at the front and rear of the grooves would be accompanied by diametric tightening up, so the bullet shouldn't go off-centre. It is also possible that gas leakage can spray atomised lead ahead of the bullet, to be ironed into the bore as it catches up. But ironed into where, if it begins in the last two inches?

I have somewhere an old magazine heralding the debut of an odd new device known as the Thompson-Center Contender, adaptable from .45LC to .410 shot. I don't know if there is any legal way to market a smoothbore cartridge pistol in the US, but there certainly isn't a commercially attractive one. So they did just the opposite of what you envisage, by producing a rifled pistol with a screw-on straightening-out tube for the shot. If I remember rightly they are vented to prevent a pressure wave as a bore obstruction, as they might otherwise would with shot, and surely would if some member of the intellectual classes fired a bullet through it.

[longbow]

Yup! I have seen those TC Contenders... in magazines only. It seems to me that they were illegal in Canada due to interchangeable barrels but I wouldn't swear to it. I've never seen one in person in any case.

The .45/.410 seemed like a good idea to me though I suspect it would appeal to a small niche group. I have read of people trap shooting with them though not at usual trap ranges.

Yes, Fosbery the ratchet rifling system though I am not sure of the benefit of it. There was a largish edge on the the thrust face of the lands with the top of the land sloped back down to the following groove. I have read that the rifling was quit deep so possibly the wedge shaped land resulted in a large thrust face but minimal distortion of the slug where flat top lands would displace more lead.

I have also read that the Paradox rifling was choked down to as tight as 0.690" from bore diameter of 0.740". I am not sure if the choke applies to both lands and grooves or lands only... which would be the result if you rifled straight through a choke. I think it would be difficult to produce choked grooves by cutting.

All in all it would be more to my liking to get an acceptably accurate smoothbore slug to work but so far I have been unsuccessful in reaching my acceptable level of accuracy to 100 yards with smoothbore slugs. I am hoping Cap'n Morgan succeeds as he well on his way with a Brenneke like clone.

In fact if I can find some Brenneke slugs or loaded ammunition I will retest as I have not shot any genuine Brennekes for about 30 years. No access where I am now.

I will also order some Thug slugs from BPI to try those out. Even if they work, it is difficult for the home tinkerer to reproduce a slug like that. Well, not the slug but the attached wad.

I did try Gualandi DGS slugs a few years ago and was not too impressed. I had some keyholes at 50 yards and recovered slugs showed that the plastic wads had rammed into the lead skirts causing distortion. Overall they didn't shoot badly, just not well enough.

The quest conitnues!

Thats for the replies so far. Keep 'em coming!

Longbow

[W.R.Buchanan]

Long Bow: What you have pictured should work just fine. I don't see any oscillation potential. Just make sure your forcing cone is all the way out to the OD of the choke tube.

That way there's no chance the slug or the debris will get shaved off during the transition.

As far as the twist rate? since you are making the tubes you can try many different rates and figure out what works best. I would point out that the really slow twists were for Patched Round Balls.

A cylindrical projectile must spin at some speed in order to remain stabilized. I think that rotation speed is a function of Length and Diameter. and if you searched around you could probably find that formula. I bet if you called Berger Bullets and told them what you are trying to do they would tell you what needs to happen.

I think at the velocities you are going to see with shotgun cartridges something more like 1:20 might be in order.

Compare the length and diameter of a .45-70 slug with your slugs. and if the proportions are similar, use that twist rate.

Randy

[longbow]

Randy:

I understand the issue with patched round balls. That is why I want slow twist. Round balls do not require a fast twist nor do "square" slugs (as long and they are in diameter). A 12 ga. ball wants about 1:120" twist so very slow. I decided to go with 1:72 as a bit of a compromise. It is fast for a ball but still slow enough that I can envision the slug picking up that spin when ramming into the rifling at say 1200 to 1500 FPS. If I am wrong and there is skidding then the 1:72" twist should still impart enough spin to make the ball accurate. That's my story and I am sticking to it... for now anyway.

I have read posts about the modern rifled choke tubes providing amazingly good accuracy but the current posters here are not confirming that nor have I seen any confirmations on other sites... or targets with cloverleafs. I suspect if it were true or even close there would not be so many fully rifled guns out there.

The Paradox guns had a very short (3" or so) aggressive rifling of some twist I believe between 1:36" and 1:120" or so in 12 ga. I want to shoot round balls or at least slugs that don't weight 800 to 1000 grs. so a slow twist is in order... I think anyway.

My understanding is that the bore guns shooting round balls used very slow twists as did the patched round ball guns.

I believe the fast twists we see today are due to the sabot slug trend. Many sabot slugs are relatively long for their diameter so require a relatively fast twist to stabilize.

I may be wrong here but I am hoping I am right. If I get this thing built and mounted correctly then only the rifling twist should be the determining factor. For mounting I plan to make a mandrel that fits the bore of the shotgun barrel and the bore of the choke tube to ensure that when the barrel adapter is silver soldered to the barrel that the choke tube is dead in line.

If I do not get decent accuracy then I will make another choke tube with faster twist and try that. If that fails well... I'm not sure but let's think positive here. I still like the versatility of the smoothbore for whatever reason, that's just me, so I'd prefer an accurate smoothbore slug which I have failed at producing (to my standard at 100 yards anyway). The next best is a removable rifled choke tube that can be replaced with a conventional choke tube for shot.

Having said that I did get some pretty darn good accuracy with 0.735" round balls shot in a borrowed Remington 870 with rifled barrel at 1:36" twist. However, it is one thing to start a ball out in a "fast" twist and another to have it meet that fast twist when it is scooting along at 1400/1500 FPS.

Anyway, we'll see shortly I hope.

Longbow

[Ballistics in Scotland]

The Hastings barrels by Verney Carron are worth looking at. As you have found, a fully rifled barrel can work well, and I doubt if it would throw an unacceptable shot pattern for small game in close cover. But rather than rifle a choke, it would be possible to ream a rifled barrel smooth for most of its length. If I remember rightly the Hastings barrels have a .716 land diameter. Hand reamers usually have a tapered lead of about 1/64in. taper, so a reamer of 18.5mm., the international standard for a 12ga. bore, should remove the rifling and give a suitable transition.

http://www.hastingsbarrels.com/

On the matter of screw-in choke tubes jamming, I think it is a possibility. Or they might come with left-hand rifling, which tends to unscrew them. The possibility of the tube heading for the horizon isn't a great one if you fire only a few shots and check it, as it can turn only a fraction of a turn at a time. Bearing on a shoulder outside the barrel might be the best plan, like Winchokes. Those are supplied with a C-wrench to turn them by one of the circumferential holes. But a stronger grip would be obtained with a circular wrench, and screws engaging with several holes.

We aren't allowed to post eBay auction URLs, which is the fastest way of getting an illustration. But if you do a search there for dog set screw or dog grub screw you will find some which would be very suitable. It would also be possible to have a concealed choke tube bearing on nothing but the threads, and prevented from rotating by a set screw through a front sight ramp. There should be no way that one could jam.

[Cap'n Morgan]

How is your Brenneke project going? It seemed like you were making good progress last post but I haven't seen anything for a while. My preference is still an accurate smoothbore slug and you were well on your way there.

Longbow

I pretty much finished the "original" Brenneke project as I felt I had achieved my aim of a decent group from a smoothbore at a hundred yards.





I'm still planning on some new nose designs on the Sleeve-Slug. One of the things I've learned the hard way over the last few years is, that the nose profile can make or brake the way a slug behaves: My first design had a nose resembling a 45 long colt, and it gave pretty good accuracy. The next design had a huge meplat - almost like a wad cutter - and while quite accurate at shorter ranges it would start tumbling after fifty yards. The last design - the "Propeller-head" - which was meant to cause a slight spin in the slug - was a hopeless disaster with the slugs dispersing all over the target.

At the moment I'm working on a buckshot #4B wad design which may, or may not (probably not), be the holy grail for a tight buckshot pattern. Time will tell...

[Ballistics in Scotland]

Were those groups with both barrels, or only one? They still turn the shotgun into an extremely useful deerhunting weapon in situations which are all some hunters encounter. Was there any choke in the gun? It has always been part of the problem to find a way of getting good slug accuracy from the same muzzle as gives a moderately close shot pattern.

I am not surprised at the failure of aerodynamically spun slugs. That is the sort of thing that is just about excusable for the experimenter in an amateur capacity, but anybody selling the things should know better. As for the large meplat, here is a picture I have posted elsewhere. It shows how a tilting round-nosed bullet increases the drag on the side it is tilting from, producing some tendency to right itself, but a large hollow in the point increases drag on the side it is tilting towards, so over it goes. An almost totally flat nose would be at best part-way between the two.

A device sometimes used in slow-twist rifle bullets was large lube grooves, vertically sided at the rear but sloping at the front. The theory (and with rifling it is hard to tell if it is totally untrue) is that it would impose straightening drag on a tilting bullet.

[longbow]

Cap'n Morgan:

Looking very good indeed! Congratulations! I know I would be happy with that group. I don't recall seeing that posted before and I try to read all you posts.

Is that group from the full bore Brenneke or the sleeve slug? Full bore Brenneke I am thinking but either way, excellent work!

I am with you on nose shape. I don't like really large meplats and my designs are mostly a moderate meplat TC. My favourite design is the Kynoch style slugs for Paradox guns. The only thing I don't like about them is weight. They are a bit heavy to go out and "plink" with but I think they would be perfect for hunting or bear defense.

Not sure how they would do if made into a hollow base design to lighten them some. Might be worth looking into.

My second favourite is the old Dixie Tusker at 600 grs. It has a nice meplat and TC nose. I am actually surprised that no-one with a rifled gun is reporting use of this nice design. I saved the drawing when James posted it and would get a mould made if I had a rifled gun.

turbo1889 posted that the Lyman 525 gr. sabot slug had too large a meplat to remain stable if shot from a smoothbore gun at supersonic velocity. He claimed that they tended become unstable at transonic velocity. I have never tested those slugs so no personal experience but turbo knows his stuff. If anyone has tested them at various ranges from a smoothbore. I'd be interested in results.

BIS:

Now there is a novel idea of reaming the rifling out of a fully rifled barrel. I hadn't thought about that one but being cheap (I like to think "frugal") I doubt I could bring myself to do that to a nice barrel. I'd rather just order a fully rifled barrel for my BPS or get a fully rifled gun.

Also, that would leave the rifled portion with shallow fast twist rifling where currently my goal is deep slow twist rifling. Not saying the fast twist won't work but it would be basically the same as a modern rifled choke tube.

Now having said that, a guy smarter than myself might have started with a modern rifled choke tube and altered from there if necessary and I probably should have gone that route using standard modern choke tube in a tapped barrel. Then if it didn't work I could have bought a blank choke tube and rifled with my machine to get the rifling I want. However, I don't have a gun with tapped barrel so decided to add on per the Cutts Compensator/Power Pac method.

I am starting to think I should have picked that route but I figured by the time I got the barrel tapped and bought a choke tube or two I could make what I want. We'll see I guess.

As for the jamming bit, that was one of my main concerns as I have read that some choke tubes do jam up very badly due to torque. However, I have not done any real research here and it may vary by choke tube design. Some seem to butt solidly on the muzzle so that should be okay. And you are right, I am sure there is a method to stop the tube from jamming so again maybe I should have gone that route. But here I am at this point so I'll carry on but maybe with some changes.

I kinda have the vision of the Paradox like muzzle stuck in my head so that is the route I have been following. That and so far I have not read very many positive things about performance from modern rifled choke tubes.

And I am stubborn. Who else would take this long to try to get decent accuracy form a smoothbore with slugs he can make himself? Well, Cap'n Morgan but the has the ability to make a commercial grade slug... or maybe better than commercial grade as they are impressive to say the least.

Here I go rambling on again. I'll be back working on this thing again later.

Longbow

[Cap'n Morgan]

Bis,
Both groups are shot from the bottom barrel (true cylinder) As I recall it the top barrel will actually print a little higher - even if the tapered layout of the barrels would suggest the lower barrel to shoot higher. No doubt the muzzle jump from recoil plays a part here.

Longbow,
The full bore Brenneke clone was used for those groups. The sleeve slug is less accurate, but not all that much, about 4" at fifty yards, where the clone will do 3" or less. So far, I have not tried the sleeve slug at ranges over fifty meters, except for the large meplat slug which started to tumble beyond that range. Since the large meplat slug mold had been re-cut from the original mold, I had to make a new mold with the original nose profile. Extra work I know, but you win some and you you lose some... I still hope to improve on the sleeve slug by tinkering with the nose profile.

[Ballistics in Scotland]

Bis,
Both groups are shot from the bottom barrel (true cylinder) As I recall it the top barrel will actually print a little higher - even if the tapered layout of the barrels would suggest the lower barrel to shoot higher. No doubt the muzzle jump from recoil plays a part here.

Longbow,
The full bore Brenneke clone was used for those groups. The sleeve slug is less accurate, but not all that much, about 4" at fifty yards, where the clone will do 3" or less. So far, I have not tried the sleeve slug at ranges over fifty meters, except for the large meplat slug which started to tumble beyond that range. Since the large meplat slug mold had been re-cut from the original mold, I had to make a new mold with the original nose profile. Extra work I know, but you win some and you you lose some... I still hope to improve on the sleeve slug by tinkering with the nose profile.

That is about what I thought. To get groups like that would be amazing if it were with both barrels, and choke. It should be possible to bring the two barrels closer together by using a lighter, faster slug. Adjusting powder alone, even if it comes within the limits of safety, is unlikely to make much difference.

If the choke tube tightens up on a flange overlapping the muzzle, you could put a thin plastic shim washer in there. I don't believe the muzzle will get hot enough to melt it, with the sort of shooting you normally do with slugs. But you could easily loosen everything up by heating the muzzle with one of those little piezo-igniting torches you fill from a lighter gas canister.

[longbow]

Another good point. I suspect that if the choke tube has a shoulder that butts against the muzzle it should not lock up too tight to remove and even if it got a bit stubborn the heating as you say should work well.

I was just cutting metal to turn for parts and am really thinking I should ha used a commercial choke tube system then just bought a blank choke tube for rifling.

Oh well, I'll get some use out of my old lathe this way.

Hah! Not to mention the fact that I am envious of Cap'n Morgan's success with his Brennekes so am thinking of revisiting my mould and making a change or two then retest those.

Too much to do and not enough time... or money!

Longbow

[Ballistics in Scotland]

There used to be (maybe still are) choke tubes intended to be permanently soft soldered into a rebated muzzle. They would be virtually invisible. Unfortunately buying a Hastings barrel just for one or two three-inch chunks isn't very frugal.

I started thinking of a tube bearing on the threads alone, with a screw in a front sight ramp preventing it from unscrewing. But with a double, of which one barrel would still be used with shot only, there is a better and easier way. That would be to cut a half-moon notch into one side of the flange, into which the unnotched smoothbore tube interlocks and stops it from turning.

You will seldom find a Paradox carried by the heroes of romance. But I can't resist posting a story in which there figures "a double-barrelled gun that could be used either for ball or shot", with cartridges with brass cases to protect them from the damp. Rider Haggard generally knew his firearms:

http://www.gutenberg.org/files/2857/2857-h/2857-h.htm

[victorfox]

Congrats brother. I wish i had the skills to do such things. I'm struggling to build a simple underhammer. My mechanic skills suck badly.. ...

[Ballistics in Scotland]

Congrats brother. I wish i had the skills to do such things. I'm struggling to build a simple underhammer. My mechanic skills suck badly.. ...

They'll be better when you finish than when you started.

[longbow]

Well, I used the "Contact" on the Holland & Holland website to ask what the rifling twist was and the gun room manager just emailed me with a response. The H&H Paradox guns use 1:30" twist which is very fast.

The Kynoch style bullet loaded fro those guns want about 1; 63" to 1:86" twist depending on what formula is used but in any case, much slower than 1:30". Not sure if they count on skidding of the boolit so not picking up the full twist rate but at 1060 FPS it shouldn't be too hard to spin that boolit when it hits the rifling.

I have now asked him why such a quick twist. No sure just how many questions he will answer but hopefully this one more. I was actually a bit surprised I got a response.

Looking through the website I have to say that they certainly make beautiful guns. I will never own one but I can window shop. If I ever win a lottery I know where at least some of the money will be going!

Longbow

[W.R.Buchanan]

LB check out this guys rifles. He makes really nice Underhammer Muzzleloaders in calibers all the way up to 12 bore. There is some info on the twist rates, and types of rifling used as well, and the whole site has a lot of info that might translate to your project, as well as some nice pics of some pretty decent custom work.

Well worth a look.

Hope it helps some. Randy

http://pacificriflecompany.blogspot....any.html#links



http://rjrenner.blogspot.com/

[longbow]

Thanks Randy. I have seen the Pacific Rifle site before.

Another is October Country:

http://www.octobercountry.com/oc-spo...72-and-75-cal/

They both run 1:104" twists for .72 cal.

At one point I contacted one or maybe both companies about supplying me a chunk of barrel to make a choke tube out of. I was declined. I can't recall the reason but that's why I decided to make my own little rifling machine.

I am set up for 1:72" twist and at this point that is what I will use unless someone can convince me it is a bad idea.

I know the big 'ol round ball guns use very slow twists and those work for round ball and that at least some of the bore guns were rifled with very slow twists for round balls or square slugs so I am a bit surprised to hear that H&H uses 1:30" twist in the Paradox guns and the rifling does not appear to be ratchet rifling. From what I see on their website the rifling looks conventional.

In any case, I know that a 0.735" round ball will stabilize in a:35" or 1:36" twist (Remington 870), that 12 ga. round balls stabilize in 1:104" twist and that the bore guns also used slow twists for balls and bullets. So, I am thinking 1:72" is fast enough and not too fast for what I want. If I am wrong, I guess I am wrong but will start with that and see what happens.

I am a bit surprised that H&H uses, and likely used in the past, such a fast twist. Not sure why as the boolit sure doesn't need that fast a twist and I can't think that it is to impart enough twist because of skidding because that could be unpredictable unless absolutely everything was identical. I have to think the boolit is spinning at 1:30" as it leaves the muzzle or lead would be shaved.

Anyway, I will try with my deep slow twist rifling and see where it gets me.

I would still rather reach my goal using a hollow base or Brenneke style slug from a smoothbore. So far that has eluded me so I will try this. I am hoping to test some more slugs next weekend so we'll see how they do first but I will likely build this rifled choke tube to try regardless of future smoothbore test results unless they are spectacularly good which is unlikely.

Longbow

[longbow]

Well, I have to say that I am impressed!

I have contacted Holland & Holland twice now and have received two responses to my questions from the London gun room manager. First was to ask the rifling twist and the second was in response to a question as to rifling form which appeared to be conventional rifling in a photo I found in a link on the H&H site ay Classic Shooting Co.

The gun room manager sent me the Fosbery patent drawings which I already have and a couple of photos which clearly show the rifling being a ratchet style rifling (though not exactly like the patent drawing) which he said was Baker rifling.

He did not have a definitive answer as to why the rifling twist was so fast for the Paradox boolit which should stabilize in no faster twist than about 1:60", simply that they had measured several original Paradox guns to determine that 1:30" was the twist originally used.

I am very impressed that someone in his position would take the time to respond to my questions and to respond quickly as well.

Should I ever win a lottery and desire a fine gun (who wouldn't!?!) H&H would be my first stop and a side by 12 bore Paradox gun first on my list.

I doubt I will ever be able to afford an H&H Paradox gun or for that matter any of their fine guns as prices for used guns seem to start at tens of thousands of dollars and range up to hundreds of thousands of dollars.

There are some other makes that are only a few thousand dollars used so maybe one day...

Back to rifling...

There is a photo of a Westley Richards Paradox gun in the NRA museum that appears to have rifling exactly as per the Fosbery patent drawings:

http://firearmshistory.blogspot.ca/2...radox-gun.html

http://www.nramuseum.org/guns/the-ga...e-shotgun.aspx

The photo of the H&H Paradox muzzles looks more like conventional rifling with a ramp on the trailing side of the rifling rather than the ratchet style Fosbery patented:

http://www.classicshooting.com/blogs...-a-paradox-gun

Longbow

[W.R.Buchanan]

LB: I made a trip to the SCI Show in Vegas last year and was amazed at the prices of used English guns.

The one in the pic below was "On Sale" at $160K marked down from $199,995! it was a Westley Richards double rifle in .450 NE and I only took a pic of the buttstock as the wood was something I had never seen before.

There were plenty more in that price range at that show.

$10 grand wouldn't even get you an Enfield Sporter made by one of the big houses! They are pretty proud of their stuff, but the work is also pretty much second to none.

These outfits invented the good stuff! And they aren't ashamed of it at all.

Randy