Okay, sure, this could go in gunsmithing, but I think big bores and doubles are loan words for each other!

I have some thoughts and ideas on the regulating process, and those will be vetted out..

but I am wondering, as I recall reading in these ages, what distance the right and left barrels should be "off" point of aim on a 577?

IIRC, the left barrel should be some left, and low of point of aim, and the right should less low and more left than the left barrel.

okay.. good news, i got that part

now, HOW MUCH? I am thinking, for the 577, that the right should be like 6 left, 3 low, and the left should be the reverse, 3 left, 6 low.

anyone know? can you stick a flash light in your 500 or 577?

I am talking 25 yards distance.

jeffe

quote:

IIRC, the left barrel should be some left, and low of point of aim, and the right should less low and more left than the left barrel.
jeffe

jeffe - the center of gravity is between the barrels and each barrel moves up and AWAY from that center during recoil.

So, yes, the left barrel should be low, but it should also (in theory) be RIGHT of the target... not LEFT of the target.

Jeff

new_guy is correct. The barrels should be low and cross. The larger the bore the more pronounced this should be to compensate for the flip or torque of the big bullets. I have a 577 that I will try and check for you but as it shoots parallel and never crosses it may be different than what you want.

A couple of lasers snap caps would be handy here.

Mickey,
would be great if you checked!

I can be totally wrong here!!!!

i thought i read the right barrel will move RIGHT as it is outside the center line. where both recoil (which is a straight back force), torque from recoil outside of the center line, and twist of the barrel

on a single barrel right handed shooter, with cast ON, the barrel still moves right due to torque from the right handed threads... same thing happens with a too short stock (effective cast ON)

(here's where I can be wrong)

the entire gun is interacting with this center line, so the weight of the right barrel interacts with the left barrel, as well
i thought i had read that left barrel moves RIGHT but to a lesser degree than the right barrel, as it's inside the center line/plane of rotation...

have shot my double front stuffers, i certain can tell that both barrels SEEM to rotate right... i'll try them this weekend and see


laser caps are coming!!!

jeffe

You're right about the rotation effect, but I think it works along the centerline of the bore being fired. The bullet turns one way and the reaction torque is the opposite, acting on the moment arm from the barrel centerline to the parallel line passing through the center of mass. This is the second reaction force, the first being the torque arount the center of mass in relation to the breech face. The second (the normal recoil) is much higher normally, I believe. You can easily see the two effects when you shoot a compact 45 pistol. On each shot, the grip will rotate your hand to the side about 30 degrees in relation to the bore centerline. However, the recoil will push the gun up and back a munch greater amount. Bottom line is I would be surprised if the barrels aren't crossed and low.

Incidentally, I would suspect that the rotation effect is the same for both barrels. Assuming the gun is built symmetrically, the length of the torque arm resisting rotation should be the same, just a mirror in relation to the plane dividing the barrels.

https://forums.accuratereloading.com/eve/forums/a/tpc/f/1411043/m/399102313

Jeff

Go here for an interesting discussion of regulation.

Everyone is makeing this too complicated! Physical regulating of a barrel set, to a known load is easier than working up a load for one that is already regulated for an UNknown load!

Micky1, take your 577NE barrel set and lock the lumps in a padded vice, with the sights aligned on a target at the distance the rifle was regulated for. NOW, take a pair of empty cases with no primers and place them in the chambers. Now look through the primer holes like a peep-sight. What you will se is the LEFT barrel will be looking at a point that is LOW ,and to the RIGHT of the point of aim on the target! The RIGHT barrel will be looking at a point that is LOW , and to the LEFT , of point of aim.

I would say the starting amount would be around 6" low, and 6" crossed on the target at 50 yds, with the sights on point of aim. AGAIN, that is, RIGHT, on LEFT, and LOW , and LEFT on RIGHT, and LOW!

The above is only a starting point. I like to drill a hole in the top rib that will be covered by the final sight ramp, and tap it, so a threaded piece of brass welding rod, can be screwed into it for a TEST SIGHT. This can be close to the final hight of the finish sight, and when the barrels are shooting right, the this test sight can be cut down to it's final hight, for the measurement of the final sight. This screw hole can then be used to hold the tinned final sight ramp while it is silver soldered to the rifle!

Don't worry about the elevation, just get the center of the group from left barrel to be about 1/2" on the LEFT of the vertical POA,on the target, and the right barrel's group center to be 1/2" on the right of POA, and with both barrels printing at the same elevation on the target. The barrel regulation is done, now the sight regulation can be done to the distance you want, as the barrels are fireing their respective bullet groups paralell to each other. This will let the inner half of each barrel's group overlap, giving youa composite group of both barrels!

All that is needed, now, is to file in the sights for POA at the range you want! For a 577NE, I'd do a 50 yd sight regulation, with a flip-up at 100yds, or even 150yds .

The use of a properly made jig will be valuable for the very slight adjustments of barrel tweeking done in this process!

>>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<

thanks all

jeffe

Jeffe

I tried Macs way with the empty case and all I saw was the neighbors backyard. Unless you have something at the other end to line up on it is the same as looking through a peep sight with no front sight, you see the whole Buffalo.

I set the barrels up on a shooting box and put the sights on a dot at 15 feet. Turned off the lights and shined a Surefire down each bore. This left a three inch circle with the center 1.5 inches low and 1/2 inch off center for each barrel. They both crossed.

I think Mac gave you the down and dirty way to regulate it. It sounds so easy until you have to do it.

Mickey,

(working with just the "right" barrel)

.5 off center from center of the barrel

.5/(15ft*12in) = .5/180
= 0.0027777777777777777777777777777778 inches per inch over 15ft

run that out to 50 yards
(50y*3ft*12in)=1800 * "taper"
1800*0.0027777777777777777777777777777778
=5" "to the OTHER side"

as I want the barrels to converge at 75 yards
0.0027777777777777777777777777777778*2700

or 7.5" at 75 yards

which is about 2.5" wide at 100


I can live with that!!!

thanks guys

I tried rad shack and a couple smallish stores for laser pointers (round)... i guess I can hit spencers tomorrow

jeffe

Mac,
aint using a torch until I am putting the rib on!!

using the plumber bands and blocks!!

I think this is, as I can see it, the fastest way to get it close

jeffe

That's fine! Keep us informed as to your progress!

I'm very interested in hearing how this progresses too!!! (If you saw the other thread on this issue, you'd know why...).

One thing about all of this that's a pain: Left barrel should point low and right (using the deprimed cartridge as a peep), the right barrel should point low and left (using the deprimed cartridge as a peep). Not sure how much -- that does depend on your rifle. Yes -- the fact that the barrels are attached to each other will increase the moment of inertia, and reduce the reaction to the bullet's momentum.

MacD37 -- one thing that has occurred to me (another question): what is the rib attached to? When it is necessary to adjust the barrels, what happens to the rib?

Dan

quote:

Originally posted by DanEP:
MacD37 -- one thing that has occurred to me (another question): what is the rib attached to? When it is necessary to adjust the barrels, what happens to the rib?

Dan

DanEP the ribs are fitted, and attached dirrectly to the barrels, and should be installed as soon as a primary regulation point is realized. The final stock shape, and weight, should be done, as well, before the regulation is done. It doesn't have to be finished, but the stock weight, and shape shouldn't be changed once the regulation is begun in ernest! After the ribs are installed, but not blacked, the final adjustments are done with the use of heated bore diameter rods, and only the solder in the last 7, or 8 inches of the barrels at muzzles, are softened, so that very small adjustments can be made, for the final regulation. Then file in the final sights, put the barrels in a jig to hold everything in place, and flux, and retouch the solder in the last 7 or 8 inches. The rust blacking is done after the barrel set is carded, and pollished. Your done!

The barrels being solidly tied together the so-called "Hormonics" that effects single barrels so much, is not important in the double rifle. Regulation is totally controlled by the recoil arch, and the speed of the bullet, (BARREL TIME)nothing more! Anything that changes the way the rifle recoils also effects the regulation. This is why you cannot place the forestock, or butt of the double rifle dirrectly on the front, or rear sand bag, but must hold the rifle as you would if shooting off hand. A double rifle must ABSOLUTELY be allowed to recoil freely as it does when shooting it off hand, or it will not shoot to the sights!

Does this answer your question?

Yes MacD, exactly what I was looking for regarding the rib. Of course, it leads to yet more questions (something that had also been on my mind...)

How heavy is the jig, and how much does that affect point of impact while regulating? Is the jig in place when you are shooting and adjusting? or having made adjustments, you go through re-soldering etc?

Dan

Long story short...

first shots... 12.5 yards
crossing left/right 7.8"

13 and 14
15 and 16

1.1" (still crossing)

So, 16 rounds into it, Hog Killer and I got it to where we have some math to help us out.

should be abou .9 uncrossed, so...

got 6.7" of of the 8.8 ..

or, 1.2 or so so move it about...


not the most kicking i've ever taken, but the MENTAL descipline was amazingling fatiging!!

there's always next week!!

jeffe

quote:

Originally posted by DanEP:
Yes MacD,
How heavy is the jig, and how much does that affect point of impact while regulating? Is the jig in place when you are shooting and adjusting? or having made adjustments, you go through re-soldering etc?

Dan

Dan, the jig is heavy as hell, about 50 lbs! The regulation shooting is not done in jig, only the adjustments! All shooting is done over a standing bench rest, holding the rifle as you would when shooting off hand. Nothing should touch the rifle but your hands,shoulder, and the side of your face. A double rifle absolutely must be allowed to recoil freely, as if you were shooting off hand. If you rest the rifle dirrectly on sand bags, it will not shoot properly, even if already regulated.

The shots are fired, then the barrels are removed from the action and placed in the jig, heated, and tweeked with screw adjustment to move the heated barrels, by twisting the barrels so they shoot at the same elevation, and the tapered barrel wedge pulled out to make the barrels shoot close together, or pushed in, the widen them apart. Then allowed to cool back to anbient temprature, before shooting the next round of shots. These adjustments are very small in the jig, like a 1/4 turn on the screw bing turned each time. This will move the barrel or wedge less that the eye can detect!

All this should be done with the shooting at 50 yds max, and no shorter than 25 yds. The final adjustments should be made with the groups shot at the distance you want to regulate for. Once they are grouping the way you want them at the distance you want to sight the rifle, the final sights can be filed in, and you are finished, and ready for carding, polishing, and blacking!

The closer you shoot, to do the adjustments, the more inaccurate the adjustments will be at longer range. Similar to zeroing a scope at 25 yds, it will still need the final adjustment at 100 yds to get it percise!

Good work Jeffe. I mentioned in my PM that I have had trouble getting hold of John, he'll be back next week, but it looks like you don't need him. I'll keep trying though cause he does have some experience and it can't hurt.

The only way to regulate a double is to shoot it! this is why they cost so much, it is a lot of work!! Unless you have a computer program like H&H does there is no other way. I am building doubles and it is a trial and error business and you spend lots of time at the shooting bench to get it right. The sad part is that each person reacts differently to the recoil, which starts as soon as the primer detinates, and thus regulating a double is more of an art form then a science!

Thank you MacD!! That pinned down most points I've wondered about!

Most competition shooting from rests (at least that I've heard of) requires the placement of your hand on the rest, rifle on hand-- does that affect point of impact? or should the shooter be shooting completely offhand? What does that affect shooting from sticks?

Dan