True reason why double rifles require the barrels set to "cross" to shoot parallel.

[Billy Boy]

It is because the solder between them effects the harmonics and the bullet will favor the other side. In practice it is almost impossible to get a double rifle to shoot to the same point of aim. You would have to experiment with soldering and resoldering, which I don't think anyone would waste time on. And even then, the harmonics are effected by where the solder attaches. It's not a constant that you can mathematically duplicate. Clamping the barrels for a test like that isn't going to duplicate an actual rifle. It is just an intellectual experiment. Barrel harmonics were not thought about back then from what I've seen. The science started to come out in the 70s.

Exactly. A barrel vibrates segmentally, like a rope ‘whipped’ from one end. Anything and everything in contact with the barrel, inside or outside, affects the position on the muzzle at the instant the pill leaves. That determines its’ angle of departure and then, where it lands. Thats’ why I love shotguns.

 

[shorthair]

It is because the solder between them effects the harmonics and the bullet will favor the other side. In practice it is almost impossible to get a double rifle to shoot to the same point of aim. You would have to experiment with soldering and resoldering, which I don't think anyone would waste time on. And even then, the harmonics are effected by where the solder attaches. It's not a constant that you can mathematically duplicate. Clamping the barrels for a test like that isn't going to duplicate an actual rifle. It is just an intellectual experiment. Barrel harmonics were not thought about back then from what I've seen. The science started to come out in the 70s.

That would certainly justify the price of a best grade from Holland and Holland and other comparable gun makers.

 

[shorthair]

Throwdown58 I agree in a sense. It is surprising how much knowledge about weapons people had in the later half of 19th century. The problem is that this knowledge was scattered through various books, magazines, newspapers etc. There was also a lot of false myths people believed in too unfortunately. 90% was forgotten then rediscovered and given new names. I don't know when barrel harmonics was defined as a term and studied systematically , but I have no doubt people back then knew barrels bend in various elastic ways during firing. One could say their experiment and your explanation are both different descriptions of the same process.

There is however one thing I don't fully agree with. One is obviously the "time wasted" on resoldering look at my other thread and you'll see I'm on the 4th resoldering of my set of double barrels now

Second is the ability to replicate. Today there is pretty good knowledge of soldering. One can imagine design of a repeatable process that reliably joins two barrels on full length is possible (using silver solder for example like Pedersoli). Then if one knows the correct principle and all the variables like pressure curve and time the projectile spends in the barrel it is possible to simulate stretching of steel using numeric methods (FEM is used to simulate loads in architecture, including vibration analysis in machinery etc). Then manual tweaking would probably be required to just get that final bit of accuracy that is lost due to tolerances in manufacturing.

The reason why it is not done is that the market for double rifles is pretty small today. The investment in writing the right design software would run close to a million $ probably(I'm a software developer by trade) . When you have customers willing to pay $50k per rifle, but you sell only few per year it makes sense to spend some time soldering /desoldering rather than investing in software.

The trial & error method was a real educational process when they first started, but they were pretty dang smart and really didn't publish a lot of the things that they had learned. Why give the competitors any help, plus labor turnover was pretty low when you start as an apprentice with Mastercraftsman as your goal.

 

[Rudyard]

[QUOTE="LawrenceA, post: 1870065, member: 44958"


When you are seeking 3 moa, it is entirely academic but I am curious.
Also if you look at pistol shooting. One person can shoot to point A and the next with the same gun and ammo can often shot at 12 oclock or 6 o clock.
I put this down to grip and the effect of recoil in a 6" barrel.
[/QUOTE]

Your too late Lawrence all the Moa are extinct. The Morri Orey et them all apparently. You have some Prehistoric bush on your side of the ditch maybe a few survived ?. I have a fishing boat friend dined on Scielocanthe. So who knows?

Regards (Being humerous) . Rudyard

 

[LawrenceA]

Your too late Lawrence all the Moa are extinct. The Morri Orey et them all apparently. You have some Prehistoric bush on your side of the ditch maybe a few survived ?. I have a fishing boat friend dined on Scielocanthe. So who knows?

Regards (Being humerous) . Rudyard

Apparently the Maori ate all the Morri Orey to boot.
But then they found some!

 

[Wildrangeringreen]

You would have to experiment with soldering and resoldering, which I don't think anyone would waste time on.

Well, having done that, because I foolishly promised my cousin's boss (avid ML'er, who was going to Africa in about a year from when he ordered it) that wanted a sxs double that they would shoot within an average of .75" of each other with a particular load at its MPBR (from my notes, a 130 yd zero, MPBR was 160 yds)... I will never promise anything like that again lol . I burned well over a pound of powder and used about 2lbs of lead and a bunch of propane and solder (and a sore shoulder) to get them there lol. He paid dearly for the gun, so it worked out, but it was so frustrating that almost made me quit lol. Wish I had backed up the pictures though, it was beautiful... from my build sheet: .50, 22" tapered 1-28" 1.125"-.8" Oct barrels, solid underlug outside of the stock, 3/4 length stock made of Purple heart, Hickory, and Rosewood laminate with "tasteful" moldings (epoxy finish), the steel pieces were a combo of mirror bright and rust-blackened, and had "tasteful" engravings ( baroque-style geometric patterns, it was the gun I actually went out and bought hand-gravers for). But a double .50 rifle shooting 130 gr. of 2F powder and a 694gr wadcutter (he got the removable pin HP mold, so he could have a "light" bullet for plains game or heavy for big game lol) isn't any fun lol. I think the clown wanted a double 50-140 "Sharps" rifle in ML form lol.

He paid $4,350 for the finished rifle, and the mold lol. It took me more time to regulate the barrels than to put the rest of the gun together and finish it lol... should have charged more for the headache (literally and figuratively) lol

Now, if I make doubles, I only build o-u doubles (easier to regulate, an inch or two of vertical difference between barrels doesn't seem to bother people as much as horizontal) but most people don't ask for them, cost too much for most uses lol.

 

[Wildrangeringreen]

Well, having done that

I had built a couple O-U combo guns prior (easy to regulate within 1-2 inches), and didn't do enough research into what goes into sxs guns to know that what I promised the guy was way up in the high end of double guns (like $20,000+ custom guns). Basically what happened was my cousin convinced him that I could make him a double that shot that load well (I wonder why no one else would touch it?), and he came by and we started talking, and I had a 50% deposit in my hand when he left. Honestly, I'm not sure I got it to .75", with the way I was printing them (mechanical zero'd the sights, bought a 36" wide roll of rosin paper at menard's, built a 6' tall target frame that could hold two sheets sxs and put a black aiming point on each and shot 3 shots from 1 barrel at the point, then switched to the other barrel and sheet for 3 shots, then overlaid the black aiming points of the two sheets, and traced the holes from the top one on the bottom one. but that last one basically looked like a bad 6 shot group from a single barrel had shot the group, and he was ecstatic (I now know why). So guys, moral of the story is... don't make promises on things you haven't done exactly that way before, without a lot of research. But I now have an appreciation and admiration for H&H and everyone else that makes good sxs rifles. They can keep it lol.

 

[Ironoxide]

Well, having done that, because I foolishly promised my cousin's boss (avid ML'er, who was going to Africa in about a year from when he ordered it) that wanted a sxs double that they would shoot within an average of .75" of each other with a particular load at its MPBR (from my notes, a 130 yd zero, MPBR was 160 yds)... I will never promise anything like that again lol . I burned well over a pound of powder and used about 2lbs of lead and a bunch of propane and solder (and a sore shoulder) to get them there lol.

Sounds about right with me it's just I burned around a kilo of powder and I haven't even counted lead...

Your reply reminded me I never replied with results of my final solder job here. In the end I'm pretty happy with the regulation. I set it to slightly converge (cross at 75m) with 80 grains of 3f. This results in approximately an inch apart holes at 50m. And the same again at 100m. I chose that because 80 grains of 3f is the most accurate load. However, 80 grains is not much in this caliber. I wanted to have an option of a heavy load too. Even if slightly less accurate. So when loaded with 110 grains 3f it shoots parallel.

With 80gr I can pretty much get first few shots go into same holes at 50m. At 110 grains those first few shots always end up in the black (6in at 100m). Now I kind off understand why traditionally black powder doubles were tested with 4 shots only. Unless one is a very good shot it is pretty difficult for your "rested" shooting to be the same as after few shots(off hand off course).

Personally I think the biggest improvement was caused by barrels being stress relieved and bores aligned vertically. Muzzles were squared to the bores and crowns recut. I only altered original regulation by 6 thou to the side resulting in regulation loads being 10 grains lower. However, those other operations resulted in a very predictable gun.

I haven't rust blued the barrels yet. I put them aside for some time(occasionally taking the gun to the range) while I'm working on other projects. I'll do rust blue finish later (it took me only 3 years to finish the Belgian gun