variations in diameter along the bore

[whitedog333]

I've noticed that there are variations of diameter inside the bore of my old rifle when I pushed a patched ball down. There seems to be areas where the ball moves easier than at the start that I've interpreted as a wider area of the bore. This might just be where the bore is cleaner though with less or no rough spots. Has anyone here ever noticed such variations within old original rifle bores?

 

[paulvallandigham]

Yes. The easy spots can be caused by improper storage, so that the bore rusted, making " hard spots", or by failing to seat the PRB down on the powder so that the iron barrel gets a slight bulge in it when the gas hits the back of the PRB. And, sometimes, the old barrel makers tried to put choke in the barrel, so that the barrel is slightly smaller( a few 10,000ths of an inch) at the muzzle, than further down the barrel.

If you think its just rust that has caused the problem, you can go at the barrel with a tight jag, and one or more cleaning patches, using tooth paste, to remove the rust and smooth the lands. This won't smooth the groove bottoms, but since the PRB rides on the lands, you will notice the difference in loading. Use soap and water to rinse out the toothpaste, and steel and rust residue, before using the gun again. Use something like Ballistol, or an oil/wax mix to coat the bore, storing the gun Muzzle down. That will keep oils out of your breech, and flash channel, while keeping the surface of the bore rust free. WD40 is also a good choice to use, and there are several commercial products like Sheath, or Barricade, from Birchwood Casey, I believe, that can be used when storing a gun long time. Be much more attentive to original barrels made of iron, as they rust so much easier than do steel barrels. By that, I mean, clean and re-oil the bore weekly. With steel barrels, depending on where you live, and the temperature, relative humidity, and proximity to salt water, you can get by with not re-oiling the bore for a couple of more weeks. Most modern gun owners just do enough gun maintenance on a regular basis. When I was a kid, the guns were cleaned every Saturday, along with cleaning the house.

 

[whitedog333]

Wow, thanks Paul. I wasn't aware of the necessity of cleaning the bore on an old original that often. I can see that I'll have to address the situation imediately because it's been a looong time since I've run an oiled patch down the bore. I'll clean it first just as you said. Yes, the rifle was sitting for a long time in a very dry and hot climate (Mexico) for many, many, many years (120 +) before it was brought to Missouri where it was stored in a garage for twenty years when it was given to me and neglected again for about 23 years. It's in stable condition now though and certainly better than when I recieved it with the barrel being held onto the stock with a long dried out piece of surgical tubing.

 

[Zonie]

Hopefully it is just an unrusted area of the bore.

If it is a bulged barrel it probably won't be a very accurate one.

 

[LaBonte]

There seems to be areas where the ball moves easier than at the start that I've interpreted as a wider area of the bore.

Another possibility is the barrel is choked, many old RIFLES were choked - they will be snug from the muzzled for 5-9" and then open up a few thoundths to the breech. This is not a bad thing..

 

[whitedog333]

Thanks Chuck. That is what it seems like the ball is doing. after a few inches, it slightly but consistantly opens up all the way down to the powder. The twist in the rifling seems to make one complete turn in the 47" barrel. Is that normal? I've never owned a modern made rifle but have owned three other originals whose twist I never checked.

 

[paulvallandigham]

After consulting a long time barrel maker, he indicates it was the practice to rifle a barrel back then so it would give one full turn in the length of the barrel. Whatever the length of the barrel was, determined the ROT. So, Yes, it was common on early rifled barrels.

Before the mid 1800s, there were just not the studies done to determine proper Rate of Twist for rifles. And, of course, this all was motivated by the growing popularity of Conical Bullets for rifles. In the 18th century, and earlier, only PRBs were shot for the most part- until the Minie ball came around. Even then, the nose heavy design of that conical with the hollow base allowed it to be shot in very slow ROT rifling. The only difference between a "RB" rifle, and a rifle intended to shoot Minie balls was the depth of the rifling, and that really didn't come about until the early 19th century.

 

[whitedog333]

That's very interesting Paul. It would suggest that the shorter barreled rifles might've been a little more accurate. However, in practice, this might not have been always true. The faster the velocity of the round ball, the faster the spin would've been. So maybe, if one gradually increased the powder charge, one could get better results? I sure would'nt want to push that hypothesis with an original. I realize that every rifle has it's own optimum powder charge and ball/patch combination for the best results, but can anyone please tell me within the neighborhood, what the correct powder charge of my rifle would've been? It's about a 385 to 390 land to land diameter.

 

[whitedog333]

Hopefully it is just an unrusted area of the bore.

If it is a bulged barrel it probably won't be a very accurate one.

I wondered about that Jim. However, after thinking about it, It seems that the patched ball starts pushing down more easily in an area that's consistently the same from a short distance from the muzzle to the breech. Hopefully, it's just where the barrel maker (Henry Leman) choked the bore towards the end. Thanks for the information

 

[hanshi]

Curiously, I have a custom rifle that seems to have a bulge or ring in the barrel. I was cleaning it one day with a tight patch and noticed a very perceptible "loose" spot in the bore. Use of a bore light showed nothing, however. But I know it's there. What I don't know is if it came that way or was something I did at some point. Regardless, it remains my most accurate rifle over .36 caliber. I've heard of this same anomaly from shooters of some smokeless cartridge revolvers & rifles. Go figure?

 

[whitedog333]

Stepping out of the ring of Muzzle loading for just a moment, I once had an early 1903 Springfield rifle whose "05" dated barrel was horribly corroded from improper or no cleaning after shooting corrosive ammo for years. I mean there were big pits down the bore that held the powder fouling that the bore brush just couldn't reach anymore. The only time I fired it, I used 3 rounds of Military spec, Frankford arsenal ammo and at a hundred yards, using the small peep sight, they grouped in a perfect triangle with less than 1/4" of paper between them. I regret selling the rifle now, but isn't it interesting what a bore with obvious imperfections can sometimes do?

 

[PeterV]

I purchased a Hopkins & Allen underhammer gun at the Jacksonville Gun show last December, and when I cleaned the barrel on returning home, I found a ring in the barrel about 8-9" from the muzzle. I pulled the breech plug and took the barrel to my local gun smith to check it out. It was a ring caused by firing the charge without seating the ball after short starting it. The gun smith said to bring it to the range and try it. The last 8 inches of the bore determines the acccuracy of the barrel, usually, anyway. I shot the rifle (.451 caliber, 30 inch round barrel) from a cross stick benchrest at 25 yards and shot a ragged hole group or over 15 shots. I decided to purchase a new barrel, 42" long, to build a chunk gun for the Sgt. York match earlier this year. The barrel wall is thick enough that, if kept cleaned, would allow someone to use this 30" barrel to target shoot and perhaps to go deer hunting from a stand. If you have strong arms, you can shoot it offhand, too.

 

[whitedog333]

Sounds like it's still an OK barrel!

 

[paulvallandigham]

You have a .39 or .40 caliber rifle, apparently with a 47 inch barrel. Only careful measurements with a caliper is going to finalize the bore diameter, and help you select the correct lead RB diameter to use in the rifle.

As to powder charge, you can begin with 40 grains, and work up to about 67 grains. At 65 grains, if your gun is loaded with the correct ball and patch combination, you are approaching 2,000 fps. at the Muzzle, and that kind of velocity is generally not needed for anything you might hunt with a .40 caliber rifle. My brother used 50 grains of FFFg powder in his .40 caliber rifle for years, and the trajectory could not get much flatter. MV with 50 grains will be around 1800 fps.

If it were my gun, I would first find a very light load for fun shooting out to 25 yds. 35 grains should make a fine light load that can be used on squirrels, rabbits, and other small game. For 50 yd target shooting, I would begin with 45 grains and work up to 60 grains. For 100 yd. shooting, I would work up to 65 grains. I have shot, and seen .40 caliber rifle shot out at .100 yds, and much further, and the rifle is accurate enough to hit bang plate targets of 12 inch in diameter out to 135 yds. Only wind causes RBs to drift far enough to miss targets at these long distances.

If you have to take a long range shot( at a marauding coyote, for instance) Wait until the wind, out where the target is, stops blowing, by watching tree limbs, and branches for their movement down range.

The slower the ball is moving, the more wind affects the flight path. So, it only makes sense that the further a RB gets from the muzzle, the slower it is moving, considering how much drag affects all RBs in flight. Your .40 caliber RB will only weigh between 85 and 90 grains, approx. and that just is not much weight to buck any kind of wind.

Most of us consider a .40 caliber gun to be an adequate deer caliber within 50 yards, in states that allow this caliber to be used for taking deer. Its a terrific varmint caliber, and small game gun. Just remember that in shooting any RB gun, drag factors reduce the MV of the PRB about 20-25%, at 50 yards, depending on caliber.

Some target shooters shoot the .40 caliber guns at those 50-60 yard matches, putting enough powder in the barrel to push the ball out at over 2,000 fps. Their reasoning is that at the target, the ball will still be flying above the Speed of Sound, and not be affected by the Transonic Zone, and the battering of the ball that the collapse of the sign waves, and vacuums surrounding and trailing the Lead RB. They also figure that the faster they send the ball to the target, the less movement will occur with any kind of cross wind. By my calculations, they may have a point, as even with the reduction of velocity due to drag factors, the ball will still be flying at 1,600 fps. at the target at those ranges. The Transonic zone is thought to begin at about 1250 fps, and goes on down through 1100 fps. The Speed of Sound is approx. 1135 fps.

 

[whitedog333]

That's some detailed and Very interesting information Paul, Thankyou Very much! I've used up to a 50 grain charge the last time that I shot it. The ball grazed a milk jug full of water and the jug ripped open on that side. That was about 60 yards. I've been cautious about increasing the load because I just wasn't sure what the rifle could take before it let go from metal fatique or whatever. However, the rifle should take a 60 and even a 65 grain load just fine. I'll top off at 60 and see how it does. I'd like to have 100 yards to shoot from a bench rest, but I've only a horse coral top rail to use. However, all the horses are feeding on the far pasture this time of year and so they won't mind the noise from so far away. I tend to move the muzzle around a bit though because I've no decent rest like a table and sand bag. It'd be interesting to see how the rifle could group in the hands of a person who could get the best out of it. I'll just have to do my best. I need to shoot at a well defined target on paper so that I can make any adjustments. Except for a little bit remaining, the original silver bladed front sight was missing on the rifle when I recieved it and so I had another one put on. I might have to trim it a little if it shoots low.

 

[longcruise]

after a few inches, it slightly but consistantly opens up all the way down to the powder.

Another thing to consider is that there may be a build up of crud on the muzzle end caused by the rifle being stored upright with the muzzle pointing up. All the crud and dust in the air builds up on the first few inches of the bore and over time becomes harder and tougher. I have seen this on two old Swiss Vetterlis and a Dutch Beaumont. It is surprisingly hard to remove :shocked2: and it does cause some pitting in the barrel but they are still shootable.

On the plus side, if it is indeed and old iron barrel, it would be less inclined to rust than modern steel.

You will need something more aggressive than toothpaste to deal with the problem, IMO.

 

[whitedog333]

Thank you very much for that information! I'll try to lap the bore out with toothpaste first and see how it turns out. If it were not for the fact that it's an original, I'd refresh the bore. but THAT would be a sin in this day and age considering it's significance. It's best to treat it as the old wall hanger that it is.

 

[Birddog6]

Curiously, I have a custom rifle that seems to have a bulge or ring in the barrel. I was cleaning it one day with a tight patch and noticed a very perceptible "loose" spot in the bore. Use of a bore light showed nothing, however. But I know it's there. What I don't know is if it came that way or was something I did at some point. Regardless, it remains my most accurate rifle over .36 caliber. I've heard of this same anomaly from shooters of some smokeless cartridge revolvers & rifles. Go figure?

That is not uncommon. I have had several of them like that in new barrels in the past 6-7 years. I am told by the barrel manufacturer that is is caused by the power being interrupted to the machine as it is reaming the barrel, thus causing the reamer to slow down & then surge as the power is back up & making the reamer telegraphs = cuts a wider spot in the bore...... You can send that to Bobby Hoyt & he can recut the bore slightly & pull tht out if it is not a major place.

However, if it is a Bulge rather than a honing mishap, I would recommend replacing the barrel, as a bulge in a barrel is stressed at that point & unsafe for use...... IMHO

 

[Dphar]

I've noticed that there are variations of diameter inside the bore of my old rifle when I pushed a patched ball down. There seems to be areas where the ball moves easier than at the start that I've interpreted as a wider area of the bore. This might just be where the bore is cleaner though with less or no rough spots. Has anyone here ever noticed such variations within old original rifle bores?

It could be rough spots rather than tight spots. In either case it likely needs lapping.
It a tight fitting wad of steel wool with some oil working the bad spots 6-8 strokes each then the whole bore 2-3 then back to the rough parts again if they seem to clean up do the entire bore 10-20 strokes at the end.
If you know how to cast a lap and have some 280 to 600 (I use 280 and 400) compound this is the best route if steel wool does not polish them out.

Dan

 

[whitedog333]

Thankyou Dan.