Denim patch for .69" ball

[dlocke]

I am going to get some .690" balls for my 75-cal. Pedersoli Bess. What would be a good diameter for denim patches cut from old, worn jeans? Maybe 1 1/4"? I plan on tracing the circles on the denim, then cutting them with scissors. Sounds tedious, but it can be quite enjoyable after a dozen beers. . . sort of like chopping up old T-shirts for cleaning patches.
DJL

 

[Rebel]

I use 1 3/4" square denim patches in my Pedersoli Bess carbine with a .690 rd ball.

 

[BRUN]

Square patches might be easier.I think they work as good as round patches.

 

[spudnut]

Or just cut em in strips and use a patchknife at the muzzle like a rifle...I use a .735 with paper cartridge I might try the 69's I know I loaned a buddy my bess for a tie breaker and I slipped a 69 ball in loose with a wad over it and he drilled the bullseye :surrender: :bow: :shake: ...Mark

 

[J.D.]

What would be a good diameter for denim patches cut from old, worn jeans?
DJL

While the diameter of the patch is important, the thickness of the patch is as important, if not more so.

IMHO, the question in my mind is not how big, but how thick the patch should be.

So, how thick are these denim patches.

A starting point for the correct patch thickness is the bore diameter, minus the ball diameter, divided by 2.

.750-.69=.06/2=.03, so that denim needs to be about .030 thick. Anything between .030-.035 thick patch for a .690 ball in a .75 cal should work well, depending how tight you want the load to be.

A tight patch/ball combnation as would be used in a rifle isn't necessary. All that is necessary in a smoothbore is a patch thick enough to hold the ball centered in the bore.
J.D.

 

[paulvallandigham]

The other consideration you need to know is that as the diameter of a round lead ball goes up( increases ), the ball will obturate, or upset more when the gun is fired, driving the cloth patch around it into the sides of the barrel. In a smoothbore, a large round ball can be loaded with a slightly thinner cloth patch, without worrying about blow by, or patch cutting. It might be hard to find any denim that will be .030 thick. However, you may find some that is .020, to .025 " that may work well enough for you. I would not recommend the same " slop " for smaller diameter round balls, and patches. however. 20 gauge ( .62 caliber) is about as low as I would go with a thinner cloth patch, again, because the size of the ball determines how much expansion will take place in the barrel when the powder charge is ignited.

 

[J.D.]

I agree with every thing Paul had to say, with the exception of obturation.

To be honest, in the absence of physical evidence, I don't know if obturation is a reality in ML guns. IMHO, I would not plan on obturation being a factor in any ML gun, and choose a patch/ball combination that gives good accracy.

Sometimes I suspect that we over think these things.

IMHO, a .715 ball with a .018 patch is a good combination in any 11 gauge, (.75 cal) gun.

This patch/ball combination can be deadly accurate on a good day, and starts with only thumb pressure.

On good days, my Italian bess shoots almost as accurately as a rifle to about 60 yards, off hand, with that combination in front of 80gr FFG Goex.

My friends shoot similar patch/ball combinations with lighter charges. One friend, who is deadly accurate, shoots nothing but paper cartridges loaded with a .720 ball and 70 gr FFG.

I don't know where he found the .720 mould, but that is what he shoots.
J.D.

 

[paulvallandigham]

JD> I Have recovered spent balls that showed that a small ring still showing the weave of the cloth patch appears where the ball met the side of the bore, indicating obturation in the barrel. Now, this was a pure lead ball, and not an alloy of lead, tin, and antimony.

 

[J.D.]

Obturation may be a fact. To tell the truth, I don't know. There appear to be valid arguments both pro and con, but IMHO, it's a mute point.

I suspect that very heavy charges are necessary to produce enough pressure to obturate a round ball. Not to mention that round balls do not have the mass of conical bullets as used in BPC rifles. There is no question that lead conicals do obturate. Pure lead round balls may obturate too, but I'm not convinced, and IMHO, it doesn't matter.

The effects of loading with a relatively hard starter COULD upset the ball enough to imprint the weave of the patch on the ball. I dunno.

Again, I think we try to over think and over engineer things that are, and should remain, pretty simple.

IMHO, find a load that produces good accuracy and don't worry about things we can't definatively prove.
J.D.

 

[paulvallandigham]

JD: I don't load a hard, patch and ball combination in my smoothbore. It goes down the barrel like greased silk. I seat the PRB on the powder like sitting exploasives carefully on the table, so I know that I am not pounding or distorting the ball. That big, soft lead ball does upset under fairly modest loads by many people's calculations.

I am using a 2 3/4 Dram load uner a 324 grain ball in my 20 gauge. Velocity is below the speed of sound. The ball upsets on ignition. As slow as FFg powder burns, it still pushes the back of the ball faster than the front of the ball moves, and that is how obturation occurs. Soft lead is SOFT.

This phenomenon is the reason that pure lead was chosen above all other metals to be used for projectiles in the early guns. It was years later that rifling was added, and more years to learn to change the rate of twist to accomodate concials, so a heavier, longer bullet could be fired accurately.

Only then did people begin to find it descirable to use a harder lead alloy, to make the bullets maintain their shape during firing, and NOT OBTURATE on ignition. when that could not be successfully done with any lead alloy, at high speed, they finally made bullets with metal jackets, first of steel, then of steel aloys, using nickel or copper, and finally copper with a little zinc throw in to harden it. Now, we see bullet being made of pure copper, in order that they expand " Like a lead bullet cored bullet will ".

And then along came some guys who still enjoyed shooting the old guns with pure lead balls, using Black powder, to cloud the ranges with smoke, and the smell of sulphr dioxide, and, gosh, they could put holes through the middle of the bullseye, too!

 

[Joel/Calgary]

Arrgghhhh!!!!



Obturation is the sealing of something, not the mechanism of that sealing. It could be achieved by piston rings in a motor cylinder, by a packing gland around a ship's propeller shaft or a water-cooled machinegun barrel, by the expansion of a shell's driving band or a minié ball's skirt, by the the tight fit of a wad/wad column, or by the deformation of a bullet's base. Whether or not this latter also happens to a round ball, patched or not, the obturation is the sealing of the bore, not the deformation of the projectile and/or the tight patch and/or wad(s), wasp nesting, or a second patch under the ball, that produces it. If a ball (or bullet) happens to upset to only partially fill the grooves of the rifling (whether Whitworth, Brunswick, Metford, Forsyth, or other), if it hasn't formed a seal, it has been deformed but it has NOT obturated the bore.



I realize some of y'all have heard some form of this rant before, but imprecision in technical usage is a sore point with me.

Joel

p.s. Paul, this is not directed at you in particular, your's was just the latest post involving obturation.

 

[paulvallandigham]

JOel: I respect the definition of obturate. But, this post topic is listed under " Smoothbore ", and I am speaking about large guage round ball loaded in smoothbore barrels, not rifled barrels. A pure lead ball is smacked in the backside when the gun fires, and the lead expands sidesways, squeezing the cloth patch between the ball and the sides of the bore. Because there are no grooves, as there would be in a rifle, the bore( cylinder ) is sealed. I believe that in this circumstance its proper to use the word obturate as you have defined it.

I understand your argument about obturation in a rifle, particularly when the seal is not perfect. If I were shooting a hard-alloy lead ball in a rifle, I would want to use something behind it to seal the bore, and not rely at all on the ball expanding to squeeze the cloth patch around it into those grooves to seal the bore. I have used .500 diameter Walter's fiber wads in my .50 cal. RIFLE, to seal the bore, and examining the cloth patches recovered from the ground indicates the wads do this job far better than any patch and ball combination I have ever found for that gun barrel. I also have used Cream of Wheat, and corn meal to seal the .50, and the patches come out looking so good, you could use them again, provided you put more lube on them. I find no large crud in the barrel using either the Walter's fiber wads or a filler, and the barrel is easier to clean than when shooting simply a PRB. When it finally warms up around here, I intend to go out with the chronograph, and shoot a variety of loads, including fillers, to see what I can learn with the machine. I will keep notes on how clean the barrel appears to be when I clean it between shots. And, I will probably crack out a can of FFFg powder and try some loads in that just to see if its a cleaner burning powder using fillers or wads.

 

[Joel/Calgary]

But paul, what I'm talking about is purely semantics - not whether or not the ball upsets, but rather that the upsetting itself is incorrectly being called "obturation", when that word actually refers to the sealing of the bore by whatever mechanisn. The deformation of the ball may or may not ACCOMPLISH obturation, but it should never be NAMED obturation.

On the mattter of sealing a rifle ball, I usually use a second patch underneath (can't in my .32 - not enough clearance around the ramrod). The extra patch is often shredded, but the regular one is usually in good enough shape to use again, though I usually use them for an over-powder patch. I keep intending to get/make sufficiently oversized wads (to accomodate the curvature of the ball) but haven't gotten around to it yet. I also want to try the corn meal.

Respectfully,
Joel

 

[paulvallandigham]

joel. My WQebster's Dictionary defines " Obturate " as, " To swell, close up, obstruct. " I think the word accurately describes what happens when a soft lead ball of the correct diameter is fired in a smootbore rifle. The same can be said of the minie ball, when its skirt on the hollow base, expands to seal the bore on firing, whether from a smoothbore like the Brown Bess, or from a shallow rifled gun like the 1863 Springfield rifle.

So, from a semantic point of argument, I don't think the use of the word " Obturate " is wrong. I do think it is not productive to assume that every ball, or hollow base bullet is able to seal off gases, foregoing the need for using a over powder wad, or filler to do that job.

I do understand how re-enactors EXPECT that their replica smoothies, and rifles work with the original components, AND their DESIRE to have fine accuracy using those components, without adding a filler, or wad. Unless these shooters are blessed with a close fitting hollow based bullet to their bore diameter, fine accuracy is just not going to happen.

Perhaps more amazing is the number of shooters who do not have micrometers, calipers, and chronographs, either their own, or soneone's they can borrow, to do the measuring and testing of loads so they can figure out why a particular load combination does NOT work in that gun, and what is needed to get it to work. I made all those mistakes as a teenager, wishing, and hoping, that a particular bullet, sized a particular size, according to a book, would shoot good groups out of an old rifle. Instead, the bullets could hardly stay on the paper off the bench at 100 yds. After measuring the barrel, I found it was way oversized for that bullet, decided to skip the sizing after casting, and lubed the bullets by hand. The groups came down considerably, and at 50 yds, I found several loads that would give me 2 inch five shot groups, using iron sights. I thought the rifle should do even better than that, and since the bore was still oversized from the cast ball unsized, I abandoned the project until I could afford to rebarrel the gun. In the process, we decided to change the caliber to one with more conventional bullets available, and the accuracy of that rifle today is outstanding.

 

[Slamfire]

Is the term "packing gland" correct in the case of a SHIP's prop shaft? I thought they used a lignum vitae segmented seal because in salt water it was self lubricating.

 

[Joel/Calgary]

joel. My WQebster's Dictionary defines " Obturate " as, " To swell, close up, obstruct. "

I don't have a Webster's at home, but all the definitions and all the technical usages (mechanical as well as medical, which I had not known about until recently) that I've found have "obturate" as a transitive verb, where the action of occluding, stopping up, obstructing, sealing, jamming up, blocking passage through, etc., has a specified object and is achieved by a separately identified mechanism. The few Latin dictionaries I've checked give obturo/obturare as to stop up or to close off, and make no mention of swelling up, but they are compact dictionaries.

The sole exception I have seen is in relatively recent popular usage in the interior ballistics of small arms, where one mechanism (upsetting the projectile) has become identified with the action and the object (sealing the bore around the ball/bullet). This has become an intransitive form (with no separate object), and it implies an restriction in the use of "obturation" from the sealing of the bore by other mechanisms. I may be old-fashioned and pedantic, but this, to me, is a misuse of the term, however pervasive that misuse has come to be.

Respectfully,
Joel

 

[Joel/Calgary]

Is the term "packing gland" correct in the case of a SHIP's prop shaft? I thought they used a lignum vitae segmented seal because in salt water it was self lubricating.

Oops - you're right. I've been away from the water too long, and was typing in the heat of the rant. Thanks for the correction.

Joel

 

[ronrryan]

Depends what you call a "ship", as bill said. I have owned and operated small vessels with shafts up to 2", and seen others larger, with packing glands that used various packing materials, often impregnated with waxes, teflon, grease, etc. Never saw lignum vitae in small vessels, I guess that is for the big boys. Good smoke, ron in FL

 

[Slamfire]

The definition of a ship was a vessel big enough to haul boats. Boats are them underwater thingys. At least that's what the Navy told me. :rotf:

 

[B.Habermehl]

Having been a marine machineist in the ship building buisness I can add a bit of info. The propeller shaft on all the civilian cargo ships I worked on used babbit bearings in the stern tube running with pressureised oil. A seal with a humungus O ring was at each end of the stern tube. The lignum viate wooden bearings were used on the rudder trunk. On navy ships at least some used bearings made with replaceable rubber staves. these were seawater lubericated. I can not speak for more than a couple of specific ships as far as the Navy goes