Barrel choice for muzzleloader build

[Greener Jim]

So here I am in gun part deprived England and I want to build a large muzzleloader.

I basically have to make the best of what I can get. Here are the choices:

1-a .620" barrel from Lothar Walther with a 1-30" twist and load paper patched boolits.

2- custom made smoothbore 4 bore barrel with the hope of patched ball or possibly slug in the future

What are everyone's thoughts on this? Practicality is largely a mute point :D

[Outpost75]

The .620 barrel with 1:30" twist would be my choice. It would stabilize elongated bullets or 20-ga. slugs with heavy loads, and could be shot economically with patched round balls using light charges, with good accuracy and light recoil.

I use a 1:28" twist .50 cal. barrel with 370-grain bullets and 80 grains of 2Fg for deer and bear hunting with fine results, and the same rifle is pleasant and accurate for target shooting with patched rounds balls using half of the normal full-charge hunting load. I would expect your 20-bore rifle would perform similarly.

[Greener Jim]

That was my gut feeling. Next question, do you think it could be made to exceed 1700 ft-lbs? I think it can looking at pyrodex data for 58 cal but if it doesn't I can't hunt deer with it here.

[Outpost75]

What you have is essentially a 20-bore rifle. A .620 round ball requires about 1470 fps. to attain 1700 ft.-lbs., which will take about 90 grains of powder:

http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/web_apps/rb_ballistics.html
Round-ball Ballistic Calculator For further information, visit the home page HERE. (http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html)

Ordinary 20-ga. shotgun slugs already accomplish what you need and you can equal that performance easily with black powder and a suitable bullet of 3/4 oz. or greater with 80 grains of powder.



20 Gauge Rifled Slug Ballistics:


Shell Manufacturer: Winchester.
Shell ID: X20RS5, Super-X.
Shell Length: 2.75"
Slug Weight: 3/4 Ounce.
Muzzle Velocity: 1,600 FPS.
Muzzle Energy: 1,865 FT.LBS.


Slug
@
Velocity
/ FPS.
Energy
/ FT.LBS.
Trajectory
/ IN.


50 yds.
1,160
981
0


100 yds.
952
660
- 5.9

[waksupi]

I would recommend a barrel with a 1- 60 to 1-66" for round ball. You will find a round ball gives you all the fun you need in a .62.

[Greener Jim]

Unfortunately that's the only barrel available tonne short of a custom one but cost is just not worth it. Plus we can't use round balls for hunting here.

I'm thinking of 590gr boolits as a minimum as I can take .732 round ball (easily available here) and hammer swage then to .62" boolits.
Obviously I could cast much heavier but I don't think anything I hit with 590 grains will get up. If I could get 1300fps with that it would be comfortably legal and very effective.

The other option of course course is a 1000gr boolit subsonic which would sure hit hard but I'm not sure it's required.

[Outpost75]

Accurate Molds has several designs of 20-ga. slugs which should work for you. Band diameters can be ordered custom to fit, so that you can reduce the bottom band diameter to approximately bore-size to make starting into the muzzle easier.

180460180461

[Greener Jim]

Luck at those dustbins! This project is getting longer legs as we speak since I've just sold my 45-120 which will finance the barrel(s) for this endeavour.

[Good Cheer]

Watching with interest.
I really like my Green Mountain .62 barrel that later got real deep round ball rifling added.
The second GM .62 barrel (still smooth bore) has been looked upon with thoughts of paper patched hollow and plain based bullets.
The one already rifled could probably be made to shoot hollow bases accurately with really stout charges behind a thick skirted minie. If I had one to fit.

[OverMax]

#1. :drinks:

[Greener Jim]

My issue with a 58 cal is barrels. Closest I can get is a .585" for the 577 nitro/nyati and the twist is way too fast.

Of course i could just buy a rifle but ideally I want a double, which limits me, and building one seems like a fun project.

[Ballistics in Scotland]

You might have difficulty convincing the authorities that a muzzle-loading rifle is legal for deer, but I think it is, in England, provided that it meets the energy requirement and uses a bullet designed to expand. In Scotland, for no very clear reason, there is a velocity requirement no muzzle-loader is likely to meet.

Getting barrel blanks into the UK is still easy, but getting them out of the US has recently become much more difficult. www.brownells.co.uk (http://www.brownells.co.uk) do offer Douglas barrel blanks in .458 groove diameter, at well over the US price, which I think would be better than a larger calibre if an elongated, match-type bullet is used. There is a 14in. twist which isn't much good to you, but also 22in. which would be fine.

I don't know whether they are imported to Brownells UK on an individual basis. But that would only be what eBay do with their Global Shipping Program (black be its fall), or an Australian auction house did with antique guns to me, to avoid an Australia Post ban. They say it is a call-to-order item, and it might be that they will only sell it to gunmakers or people whose certificate already includes such a rifle, but nothing in the law requires this of them, as long as it is unthreaded and unchambered. I have a letter from the Department of Import Control saying so, though much good to me it is now that US export has been made prohibitively difficult.

A 4 bore shotgun would certainly be adequate for deer at close range, and would compensate for the lack of a quick second shot, although of course a double 4 bore would be better. Everybody should have one. But the circumstances, and the shooters, which make it legal for deer are very limited. Shot not smaller than the AAA size (5.1mm., or very close to US No2 buckshot) can be used in a shotgun not under 12 bore, or a non-spherical slug not under 350gr. (although a good round ball load can achieve pretty fair accuracy, and something like the Forster slug may not.) But these are only allowed to stop predation on crops or forestry. It is debated whether the shotgun or close-season exemptions apply to a casual friend of a farmer, and the deer have to actually be doing it, rather than just someone thinking it would be safer not to have so many deer around. How much the police know the subject, and how accommodating they are, varies from place to place. But I have found them generally pretty reasonable on that sort of point. I produced a ballistics program table to suggest that my .40-82 Winchester with a light revolver bullet could achieve the 2,450 ft./sec. required for deer in Scotland, and they were quite happy to agree.

Legally there is no such thing as a rifled shotgun in the UK. If it has rifling it is a rifle, and if it has a smooth bore it is a shotgun. A fragment of good news is that if you have a muzzle-loading shotgun on a shotgun certificate, which is pretty easy to get and allows you to buy or make as many shotguns as you like, you can load it with anything except explosive or gas shells. It seems a pretty tortuous system, but take into account that it is a very crowded country, and it seems about as good as anybody's. With different seasons for bucks and does you can shoot deer any day in the year, without praying you don't like like a deer on opening day. In France and some other countries in effect anybody can hunt, but when they visit this country they are amazed to look out the window and see wildlife going about its lawful affairs.

[Ballistics in Scotland]

I think a 1:30 twist for a .62 cal or larger is a very fast twist for a round ball. It may be hard to get acceptable accuracy with the velocities needed to attain the energy levels your looking for. The Greenhill formula for calculation of rifling twist works very well, and is spot on for the use of accurate hard hitting round ball loads. Take your bore diameter of .62 and multiply by a value of 150. This gives you 93, so the proper twist for this caliber, that will give very good accuracy with hunting loads is a 1:93 twist. I have used this formula when having my barrels made and get great accuracy.

You might well, but that calculation doesn't give a 1:93 twist as smallarms engineers usually term it. Greenhill's formula, for a bullet of about the density of either hard alloy or pure lead plus jacket, states that bullet length in calibres multiplied by rifling pitch in calibres should equal at least 150, although in practice 200 will often stabilise a bullet. If you consider a round ball as one calibre in length, it gives a twist of 93 calibres, or 57.66in. In fact a round ball appears much more easily stabilised than a cylindro-conical bullet. You would be fine with a twist of 60in. r so as Waksupi suggested, but there is hardly any twist that is too slow for one.

Anyway, the OP didn't want to use a round ball. It shouldn't be a huge issue in a .62 rifle, since an elongated bullet will increase recoil rather badly. I think the only way it complicates the legality of using a muzzle-loader is if it is a smoothbore. But that is what he said.

[Greener Jim]

Thanks for the replies. I shall address jjarrell first; although I have zero idea whether your calculations work or not I shall bow to your experience in this, however there is no way that hunting with a roundball would be legal here so I am afraid I won't be able to take your advice. Thank you for taking the time to pop it all down though.

Ballistics in Scotland; I think a .62" muzzleloader should be legal in England and Wales as you do, that is if I can hit 1790 ft-lbs and use an expanding bullet. If I use a hollow nosed cast bullet I'll be fine and BASC have confirmed this. The law for England and Wales says "soft nosed or hollow nosed" as opposed to Scotland where it's "a. Hokey designed to expand in a predictable manner". So I think I should be fine.

The 4 bore would be a strictly bird gun whilst in the U.K. But with the possibility of ball/slug for abroad. I of course wouldn't need to justify a 4 bore shotgun either which makes it a good back up plan if I can't get a variation for a 62 cal rifle. I would however need to justify the slugs.

[John Taylor]

Might try calling Jim Carpenter ( 208-582-2091 ). He make very good barrels at a reasonable price. I have used several of his barrels.

[Greener Jim]

Sounds like a good man to use but unfortunately it's not cost effective once the barrel gets this side of the pond

[Ballistics in Scotland]

Thanks for the replies. I shall address jjarrell first; although I have zero idea whether your calculations work or not I shall bow to your experience in this, however there is no way that hunting with a roundball would be legal here so I am afraid I won't be able to take your advice. Thank you for taking the time to pop it all down though.

Ballistics in Scotland; I think a .62" muzzleloader should be legal in England and Wales as you do, that is if I can hit 1790 ft-lbs and use an expanding bullet. If I use a hollow nosed cast bullet I'll be fine and BASC have confirmed this. The law for England and Wales says "soft nosed or hollow nosed" as opposed to Scotland where it's "a. Hokey designed to expand in a predictable manner". So I think I should be fine.

The 4 bore would be a strictly bird gun whilst in the U.K. But with the possibility of ball/slug for abroad. I of course wouldn't need to justify a 4 bore shotgun either which makes it a good back up plan if I can't get a variation for a 62 cal rifle. I would however need to justify the slugs.

Well nothing in the Deer Act applies to wild boar, or the wild goats I see in the SW Scottish hills. There are places you can shoot them, for a fee unless there is a need for control.

In the UK we need specific authorization to have expanding bullets, which is granted only to people who intend game shooting. But it is pretty well established that a cast lead bullet can be a non-expanding bullet if you aren't so authorised, or an expanding bullet if you are, even if it is the same bullet. You would also need specific authorization to have cartridges loaded with single slugs, or shot of over .36in. diameter, or less than five shot. But you can have the slugs on their own, round or not, just like the ones I used to make holes in with a bench press for fishing. As they never turn into cartridges for the muzzle-loading shooter, you can fire them at anything except deer.

[Greener Jim]

So I could have a smooth 4 bore muzzleloader and practice with slugs without the need for them on my FAC?
That definitely makes it interesting if that is the case. I would need confirmation from somewhere to be sure mind.

[Ballistics in Scotland]

So I could have a smooth 4 bore muzzleloader and practice with slugs without the need for them on my FAC?
That definitely makes it interesting if that is the case. I would need confirmation from somewhere to be sure mind.

It's all in here. You need a firearm certificate to possess single bulleted cartridges, but components of ammunition aren't cartridges. A shotgun certificate doesn't specify conditions on what it may be used. Of course they might pester you considerably before accepting the situation. But I have never in my lie seen a policeman while shooting.

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/518193/Guidance_on_Firearms_Licensing_Law_April_2016_v20. pdf

A club range might well have a limited range certificate. You should make sure the club officials don't think you are pushing them out on a limb. But if it covers bulleted firearms, it probably species only a velocity a 4 bore is unlikely to exceed.

[Greener Jim]

I had a look on there when I posted earlier and 100% agree with what you say above, i spoke to a mate who shoots a couple smooth rifles and he says the same as well.

I do wonder about the boar, that sure would be interesting.

[Good Cheer]

Just a question out of curiosity.
For a .62 are you going to use a heavy breech and tapered round barrel to get strength, length for velocity and reduction in weight for a hunting rifle?

[Greener Jim]

Something along those lines. Strength is obviously the no1 concern but after that is weight. I'd like enough that recoil isn't an issue but carrying it is also important.

That been said, 4-bore is looking more and more achievable and that would be a 20lb gun

[Ballistics in Scotland]

It could be 20lb., which would help make the recoil manageable, but a more typical weight for a double 4 bore would be 16 to 18lb. Greener preferred the 8 bore, which could weigh 11 to 14lb., and in rifled versions with (slightly) elongated bullets could handle considerably more than half the weight of powder and lead. He considered that rifling didn't have much point in the 4 bore, which was always a close range weapon, and it produced greater recoil. But it was worth having in the 8 bore.

He wrote at the time of the black powder express, or "nitro for black" loads, and thought that the 8 bore offered a worthwhile advantage over the .577, but the smaller "bore" rifles (although the 10 bore had been quite popular on Indian and SE Asian elephants) had no such superiority over more modern cartridges. Those who write here of experiments with smoothbore slug and round ball wouldn't be surprised to find him saying that you could do well with either at sixty yards, but not nearly in proportion at a hundred. I always think of this the hockey-stick trajectory, straight for a while and then taking a turn.

I don't know what material you plan on using for the barrel. Some people on the boards have spoken scathingly of cold drawn seamless mechanical tubing, which is the main source of thick wall tubing. It is only mild steel (which is not in itself a big issue, as shotguns have been made of mild steel for over a century), and while hydraulic tubing may be better, it is thinner. I think you would really want to use the weight you would save by not having a double.

One possibility would be to line it with a much stronger material. Now I am speaking of what I haven't done, and maybe nobody has. But some extraordinarily high quality tubes are made for bicycle frames, often butted, or thickened, at the ends. Here are a couple of good websites, and the Wikipedia article on Reynolds, who have been the big name in the field in the UK almost since bicycles hit the street.

http://www.ceeway.com/acrobat%20files/Columbus_Tubi_2016_Catalogue.pdf
http://www.torchandfile.com/nbspReynolds-Parts-List-2016_c_74.html
https://en.wikipedia.org/wiki/Reynolds_Cycle_Technology

Most are too short, or some peculiar cross-section or curvature. But you might find something usable, and it may be that some of the manufacturers have diversified into similar tubing for other applications.

[Greener Jim]

This is why I should use this forum more. I very much admire Greener's work and had heard the first paragraph before, however the second was new to me so thank you.

To be honest, to alleviate my strength concerns I would be getting the barrels made by a barrel maker.
As for the weight, I know I could go lighter but I really want to be sure of strength. The issue is that it is hard to work out what pressure a muzzleloading 4-bore runs at so I am airing on the side of caution.
Cautious plan is 27mm bore, 41mm OD for a 7mm wall.
Less cautious but still safe (based on educated guesses on pressure) is 27mm bore, 37mm OD for a 5mm wall.

The latter reduces weight over the former by over 5lbs!

[Ballistics in Scotland]

This is why I should use this forum more. I very much admire Greener's work and had heard the first paragraph before, however the second was new to me so thank you.

To be honest, to alleviate my strength concerns I would be getting the barrels made by a barrel maker.
As for the weight, I know I could go lighter but I really want to be sure of strength. The issue is that it is hard to work out what pressure a muzzleloading 4-bore runs at so I am airing on the side of caution.
Cautious plan is 27mm bore, 41mm OD for a 7mm wall.
Less cautious but still safe (based on educated guesses on pressure) is 27mm bore, 37mm OD for a 5mm wall.

The latter reduces weight over the former by over 5lbs!


Only the weight of the unturned tube. The taper of a shotgun barrel is nowhere near in proportion to the pressure, and near the muzzle it could be as thin as paper if pressure was the only consideration. (It isn't, though, as barrels get dented very easily, and might at some time have to be reduced by rebluing or lapping to remove pitting.) So if you keep the breech area thick, and taper down to conventional muzzle diameter, you don't add anything like that 5lb.

27mm. is a little larger than 4 bore. I have seen it quoted at .935in., but it should really be the 12 bore diameter multiplied by the cube root of 3, i.e. about 1.05in. While 5mm. walls in mild steel should be all right if the steel is good, but not if it isn't. 44.45mm. with 9.53 walls is actually 1¾in. and ⅜in., and for a single barrel that is what I think I would use. That way you could give the barrels the concave curve along their length which is almost universal in shotguns.

However you taper it, you can't just rely on an apparently straight bore giving you even thickness all the way round. It may take some curvature as you release tensions in the steel, and curvature makes a thin spot. The proper gunmaker's tool (of which you can make a good copy) is a sort of steel tuning fork of which one end with a small transverse stud goes down the barrel, and the other has a dial gauge to measure the distance from it.

www.trackofthewolf.com's (http://www.trackofthewolf.com's) print catalogue, even better than their print catalogue, is a valuable resource. I don't think they have breechplugs big enough for you, but with hacksaw, files, a Dremel tool and carbide burrs you can copy them.

One important legal point in the UK is that rifle parts (the ones which actually bear gas pressure) are firearms, and you can only have them once the variation is in your firearm certificates. Smoothbore parts of all kinds (other than short-barrelled) are uncontrolled, and you only need to notify them of acquisition when you have made the gun functional.

[Greener Jim]

I do agree that tapering the barrel is the right way to go. Unfortunately that's not something I can do myself which is why I wanted to stay away from it. Maybe I just have to accept the extra cost and go for a taper.

So on that note, based on a 1.75" diameter at the breech (for the first 4"?) with a 1.063" bore, what would you taper down to at the muzzle?
I would be using black powder (well pyrodex) which obviously has a much different pressure curve to smokeless.

[Ballistics in Scotland]

Repairing a gun for someone without a registered firearms dealer's licence is illegal in the UK, and while helping but not completing the manufacture of a part is probably legal, I think you would find an engineering workshop reluctant to do it. Of course they could be fooled into it, but I really would recommend staying completely legal on this project. The last thing you want is an indignant engineering firm bitterly denouncing you. Besides, when you turn up with your shotgun to be placed on licence, part of the pleasure is explaining how you did it all totally legally.

With a powerful bench sander and the coarsest silicon carbide or zirconia belts you could grind it to an octagonal taper. Or you could rig up a wooden jig in which the barrel is clamped and moved a little at a time, as you slide an electric router with tungsten carbide burrs back and forth along its length.

As I said, pressure isn't much of a factor for thickness at the muzzle. I would think an eighth of an inch would be more than enough, but give you the weight you want. If you are using cold drawn tubing, it might be worth finding someone who can Magnaflux test it for you, when you have removed as much metal as you are going to. That is a process which temporarily magnetizes it, to show up in a sort of magnetic ink whether there are any invisible flaws in the structure.

[longbow]

It seems to me that there was a thread by a guy who built a 4 bore double rifle but I have not managed to turn it up using the search. I even tried deleting the 4 bore bit. I did not find that thread but I am sure it is here somewhere. He has a machine shop and was building from scratch so I am sure there would be useful information if only I could find it.

I am sure you will be able to find suitable 4140 tubing to make a barrel out of and there should be proof load info available as well... at least somewhere. I did a quick search but struck out. The proof pressure will likely vary by bore size and I suspect that 4 bore will be pretty low. I did find reference to 12 gauge BP proof indicating 7000 PSI though you would want to confirm but I have to think that if the material will withstand typical 12 ga. proof testing it will be suitable for 4 gauge loads. Not sure how muzzleloader proofing works in the UK or whether even required. If legal or course you can do the test yourself following typical proofing methods to ensure the barrel is safe at the loads you want to shoot.

I did find this video of a bore gauge gun being shot with the comment that the load was a 1750 gr. lead bullet over 325 grs. of GOEX Fg powder:

http://www.guns.com/2016/03/04/firing-a-gigantic-4-bore-rifle-video/

You might try the nitroexpress forum or the doublerifleshop to see if anyone there has info or experience.

Not a lot of help, sorry.

Longbow

[Ballistics in Scotland]

Here is one of the threads you may have seen, and huntingsgr8 and Omnivore's other threads are probably the ones to look for. Beware of what you see on Youtube, for I think a lot you see there hasn't been done, or has been done with loads other than those claimed. There are people on Youtube who are about as useful as a retriever on a hand-grenade range.

http://castboolits.gunloads.com/showthread.php?298289-4-Bore-Proof-Test-And-Results

As to proof in the UK, it is compulsory to sell a firearm, other than an antique, to a member of the public without British or other proofmarks recognised by law. Not only must they exist, but the strength of the firearm mustn't have been weakened in such a way as to make it out of proof. You don't need them to have, manufacture or shoot a firearm, or to sell it to a registered dealer.

WW Greener's proof charge table, for smoothbore breech-loaders, only goes up to 5 bore. But the largest of three sizes which were sold as such, 5/2, was 1.02in., and therefore very close to 4. The provisional proof charge was 740gr. of Tower Proof black powder (27drams) and 1421gr. of shot. The definitive proof was 492gr. powder and 1912gr. shot. In both cases the "shot" may have been a solid lead cylinder, which would if anything reduce the pressure.

The supplementary proof for smoothbores intended to be used with smokeless powders did go up to 4 bore, for which 301gr. of the finer grained TS2 powder and 1805gr. shot. This was still a black powder, probably because it was more predictable than smokeless at that time.

One of the great myths of the present day is that black powders give much less pressure than smokeless. The maximum in a totally sealed vessel is considerably lower, and also the burning rate of smokeless accelerates much more in response to pressure than that of black powder does. Put simply, that means that anything which tends to increase pressure, with smokeless, will increase it rather a lot. With shotguns and pistols, and even some of the early smallbore military rifles, the pressures generated by the two powder types were very similar.