Leading

[cbourbeau32]

At what velocity does leading begin to happen with cast bullets? Charlie

[Castaway]

Sorry to say, there isn't a definite answer to your question.  Leading is a function of many factors.  In optimum conditions, if the barrel is smooth, the alloy is right, the bullet mass is correct and the load and lube are a proper match, leading may not occur until upwards of 2,000 f/s give or take a 1,000f/s or so.  Add a gas check and the above might or might not go out the window.  Leading also occurs at low velocities, mainly because the bullet isn't behind enough pressure to bump up the base of a hard bullet to seal the bore.  Other factors include bevel base bullets (bad, bad, bad) and powder selection. 

[Lloyd Smale]

im not a big fan of the bumping up to fit theroy. If a bullet needs to do that its because some dimention of your gun or bullet isnt right. IF you have the proper sized throats and bore and you have a good forcing cone and cyl/bore alignment theres no need for a bullet to bump up and if you dont I can about guarantee your going to have some ammount of leading no matter what you do. Ive pushed pure lead bullets in a good gun at close to 1000 fps without trouble. Now a gun needs to be dimentioned properly and have a good barrel to get away with and a good lube is needed but it can be done. Ive seen air cooled ww bullets pushed to close to 2000 fps in rifles if everything is right. Ive allways had better luck with bullets on the hard side in a good gun. If you think about it, using a soft bullet and counting on it to bump up to fit your gun and expecting guilt edge accuracy is just not possible. What your asking the bullet to do is deform to fit your gun and how can a bullet that deforms be expected to shoot one inch groups. Now bumping up has its place and may take a gun that shoots 5 inch at 25 yards and cut that in half but unless your gun is right to start with your a lucky sob if you get any better. I know the old timmers like Elmer kieth preached the bullet bumping up routine but you have to keep in mind that alot of what they were shooting were either colts that were way out of spec and smiths that were so well made back then that about any alloy would do good out of them. Also i doubt that alot of those old timers had access to good printing lead and wws were hard to find as horses didnt use them so they used about anything they could get which was for the most part pure lead and tin.

[cbourbeau32]

Thanks for the reply Lloyd but I'm not sure what bumping means. I just wanted to know what the general consensus was on about what velocity noticeable leading would start to occur so I could stay a little below that. Charlie

[MePlat]

Lloyd Smale:  Interesting thing about oldtimers and their bullets.   Elmer Keith called a 1-16 tin/lead alloy hard.  Today it is considered soft.  In  his later years he rarely cast his 44 bullets having plenty of people giving him bullets etc.  A guy in Philly named Rissel cast him bullets that were 1-10 that were top quality as I ordered bullets from him too.  Most of the bullets Mr. Keith received from people were freebies.  Cast of varying alloys, bullet lubes or various brands of lubes,  sized to different diameters I would say etc.. 
I have been using cast bullets for years and have yet had a bad leading problem except for some ammo I bought for my first Super Blackhawk that I purchased new for 125 dollars.  The ammo was from Tri-Test Munitions that is now long defunct.  A local discount store had them.  The gun leaded bad and I mean bad.
In this light I wonder what the chamber throat diameters were on Mr. Keiths 44 Mag M29 that he carried daily?  I bet they were generous as tight throats for the 44 Mag did not happen until in the 90's if I remember correctly.  I have a 44 Mag M29 that I bought way before the pinned in barrel was dropped that an XTP will rattle in while my stainless mountain gun the bullet won't even go in.
I'd say  large throats  sure didn't affect Keith  shooting.  Nor did the various alloy hardnesses either.
I used to call and talk to Mr. Keith several time a year from about 1972 till his stroke in 2001.  I think the last time I called him was about a month and a half before the stroke.
Do you know what he considered his best handgun shooting of his career? That was one question of the many over the years that I asked him.

[safari]

I'm no expert on cast bullets, but I'll throw my 2 cents in on this. I'd say if your reloading any of the commercial hard cast lead bullets out there, if you keep them under the 1000fps range you'll do allright, and yes, the bevel base, hard cast that your commercial casters sell us at a reasonable cost aren't the best design for accuracy, but there cheap and they sell. My rule of thumb for the past 30 years or so is that if its a plinking /target load, any of the commercial casted bullets over a dose of Unique(or any other suitable powder) at about 750~900fps is ideal, and won't give leading problems other than average routine cleaning. I've also sent many thousands of the Speer and Hornady swaged lead bullets down range also, they do fine if you keep your velocity at respectable target levels. Now if you're wanting to make major for one of the action pistol games or you want magnum velocities  with your cast loads, that's a whole other problem. Then you either need to spend the time and money on fine tuning the handgun to an optimal bullet diameter to minimize any leading at higher velocities, or spend a bit more on your cast bullets to get a better quality product, i.e. gas check, to eliminate leading at the magnum levels.  Nowdays I'm loading alot of commercially casted bullets for cowboy action shooting, at around 750fps, and have no noticeable leading, nor do I with my 1400fps loads with a WFNGC bullet out of a 44mag. Just pick an appropriate bullet for the level you want them to perform at-

And to answer your last question, I remember from long ago someone told me that if you keep plain cast bullets under the subsonic/hypersonic threshold 1050~1100fps or so, you won't need a gascheck, but anything over that it was good insurance to keep from leading up your bore. But some of your store bought bullets of today are so danged hard, and use that cheap blue crayon lube, that I keep them well under the subsonic threshold, and buy better LBT style bullets for the magnum hunting applications.

[Lone Star]

I suggest that anyone with their own "theories" about leading read what was discovered by the Cast Bullet Assn. and others almost 20 years ago.  Simply put, almost all leading is caused by gas cutting of the base and sides of the bullet.  This happens when gas is allowed to get past the bullet base - it vaporizes the lead which then condenses on the bore.  If you can keep the gas behind the bullet, leading can be eliminated  to over 2400 fps.  This latter was done through the use of a plain base bullet and a long column of cereal filler.

Bullets must bump up to fill the throat and the bore to stop the gas.  To eliminate leading, the hardness of the bullet much be matched with the pressure of the load, other wise the bullet will allow gas around it.  Recover a few bullets from a load which leads and you'll see bad gas erosion on the sides, usually along the joint of the grooves and lands.  Recover a bullet from a load which does not lead and there will be no gas cutting.

Some of the worse leading I ever experienced was with a .45LC revolver and 255-grain bullets cast of quenched wheelweights (pretty hard) at low velocities.  I started low with Unique (~850 fps) and leading was terrible, as was accuracy.  I increased the load in 1/2 grain steps, and when I reached ~1050 fps the leading disappeared - and accuracy was very good.  I repeated the test with a softer alloy and it didn't lead at 850 fps.....because the bullet was soft enough to bump up at the lower pressures and seal the bore. Bullet diameter is not enough, the test bullets were a tight fit in the throats and almost 0.002" over bore diameter.

Much of what people "know" about leading is based on heresay and the opinions of a few gunwriters of old.  Modern cast bullet afficianados know the thruth - until someone else proves different.   

.

[quickdtoo]

Thanks for the reply Lloyd but I'm not sure what bumping means.

here ya go Charlie...

http://www.sixguns.com/crew/obturation.htm


Here's one man's opinion on the topic as it applies to a revolver..

What About The Idea Of Bullet Base Obturation Being Necessary To Revolver Accuracy?


This idea has merit when the bullets do not properly fit the cylinder throats of a revolver. The concept relies on this premise: The bullet is undersize for the cylinder throat, and therefore when the bullet hits the forcing cone, and is still in the mouth of the chamber of the revolver, expanding powder gasses leak around the base of the bullet when it hits the resistance encountered at the forcing cone. This leaking gas will cause "gas cutting" at the heel of the bullet, thus severely deteriorating the potential accuracy of that bullet. The theory, or practice here, is to use a bullet hardness that is matched to the pressure generated by the given load in order balance the pressure necessary to obturate (read deform) the base of the bullet to totally seal the chamber mouth before the bullet hits the forcing cone, thus preventing the "gas cutting" and enhancing potential accuracy of the load.
This concept does work to a degree, and can greatly enhance the accuracy of some load/bullet/revolver combinations. However, it is flawed in its conception of being the perfect scenario. Please consider that if the bullet is undersize for the cylinder throat, that it will most likely be laying at the bottom of the chamber (Yes, at the bottom of the chamber! Remember that the chamber has to be bigger than the cartridge for it to easily chamber, and that the cartridge will lay at the "bottom" of the chamber, even if it is just a few thousandths of an inch!) upon ignition of the cartridge. Consequently, when that bullet, that is undersize for the throat of the chamber, obturates under pressure of the expanding powder gasses, it is already out of alignment with the forcing cone and the central axis of the bore by a few thousandths of an inch. Now, considering this aspect, the bullet will already be against the bottom part of the throat of the chamber once the bullet's base obturates (deforms), the odds of that bullet uniformly expanding at its base are really unthinkable. It will expand into the unfilled space of the throat, and thus the bullet will remain slightly off center in relationship to the central axis of the bore, and will remain that way throughout its passage through the barrel! Yes, this bullet will most certainly shoot better than if it did not obturate, in that the powder gasses were sealed in the chamber mouth and the base of the bullet did not become eroded from escaping gasses. This concept does have its limited merits.

Now, consider a more precise, and predictable alternative. If the exact dimension of those chamber throats in the cylinder are known, from slugging and measuring, then a bullet of the exact same dimensions can be procured to fire in that particular firearm. This being the case, the bullet will be a firm, snug slip-fit through the throat of each chamber in the cylinder. With a bullet that already tightly fits the chamber throats, it is not necessary for the bullet to obturate in order to seal the mouth of the chamber when that bullet hits the forcing cone and pressures climb. It fit the throat BEFORE firing! Carrying this one step further, the loaded cartridge, with a bullet that is a snug slip-fit in the chamber throats, will automatically center itself in the chamber, due to the tight dimensional relationship between the bullet and the chamber throat. No longer does that loaded round lie in the "bottom" of the chamber, but rather is centered by the bullet in the chamber throat, establishing near perfect alignment with the central axis of the bore, (assuming good cylinder timing and bore alignment), before the projectile is even launched. The result is much more predictable ballistic performance and more forgiving load development, as well as reduced leading in the forcing cone and rearward portion of the barrel.

This is the main reason that Beartooth Bullets stresses custom sizing for our customers, and encourages each of our clients to determine the exact dimensions of their firearm chambers to ensure proper bullet size application. When this dimensional relationship described above is properly balanced, bullet obturation no longer plays a role in bullet accuracy or load development. The bullet will already fit the gun, and not need "pressure fitting" by obturation (read deformation).

http://www.beartoothbullets.com/faq/index.htm

[cbourbeau32]

Thanks everyone. Thanks Tim you are answering my questions even over here on the handgun page. So if I use gas checks I should be safe with about any velocity that I am tough enough to shoot out of my 4" 629 then right? Thanks, Charlie

[quickdtoo]

I have no revolver experience, but gas checks and properly sized cast bullets have been shooting great in my rifles with all loads, mild to wild.

Tim

[paul105]

Do you know what he considered his best handgun shooting of his career? That was one question of the many over the years that I asked him.

MePlat, you're killin' me -- what's the answer?

[Lloyd Smale]

safri im not vane enough to agrure with some of the old experts but my point in this whole thing is that IF a gun is built right to start with bullets will fit properly without the need to bump up. If a gun is built to correct dimentions you will almost allways get better accuracy with harder bullets. Many people including Veral smith will agree with this statement. To think of it in an easy way to understand is relating it to jacketed bullets which are way harder then any lead alloy. Most compititon shooters and even me at times will go to a jacketed bullet for comp because there usually a tad more accurate and you dont have to push them over 700 fps with a low pressure load to get accuracy. I make the statement I made from experiece not from reading someone elses opinion. Ive spent more time benching handguns in a year then most do in a lifetime and bottom line is that hard bullets will outshoot soft ones 9 out of 10 times. But the results here are based on my guns and theres not a one of them that hasnt been altered in some way to get the dimentions right.Its a rare gun that comes from any manufacturer that couldnt stand a little tuning. Recently my buddy and i did some pretty extensive testing with  a colt gold cup a smith 625 45 colt another one in 45 acp and two super blackhawks and a 45 colt vaquero probably a 2000 rounds of ammo varying the  powder charge and primers and bullet designs and alloys. We tried pure, 5050 ww/pure. straight ww. Wheelwieght with 3 percent tin added both air cooled and water dropped and 5050 ww/lyno and  strainght lynos. Just about straight across the borad the harder the alloy the better it shot. It effected accuracy at leadst as much as switching powders and probably more. Im no expert on what a guy has to do to make rifles shoot cast but Ive put many many hours on the bench with handguns and sure know what works in my guns In my opinion if you need to rely on bullets bumping up to fit a bore the gun needs work. One thing i cant tolarate is a gun that isnt right. I dont care if there isnt a  bit of blueing left on it or it looks like it was drug behind a truck id take it over a pretty gun that isnt. Best suggestion i can give to you and everyone else is to spend the time to test it yourself. Theres people that beilieve both sides of the argument  but reading aboiut it aint making your gun shoot any better.

[kennisondan]

I am trying to follow the thread, and may have missed it, but do you guys think that you must do one or the other to get accuracy and no leading : the bore should be slugged / measured by driving soft lead down the bore and into the chamber area, or second :  you tune the gun to more standard or more consistent dimensions ? Or do you tend to do both ?  does one foreclose the need for the other ?
thanks
dk

[Mikey]

Lloyd, Lonestar, Quickdtoo:  Thank you all for your responses, they are encompassing and informative.  I think I now understand (well enough to speak to it) why some of the slower, plinking loads I tried developing for my 44 mag leaded so badly with hard slugs.  I think I also understand why some cast slugs I tried working with in my 45 acps leaded so badly as well.  I am really pleased, and grateful, that we have as many experienced and knowledgeable shooters responding to questions like this.  You folks are what makes this site so informative.  Thank you all.

Charlie - here's my 2 cents worth:  I have been a fan of gas-checked slugs for a while and have been a fan of Beartooth Bullets for as long.  Every gas-checked slug of theirs I have shot has performed perfectly for me without leading.  I have found, in conjunction with the Beartooth concept, that properly sized bullets give me the best accuracy and do not lead my bore.  This is especially true with the use of gas-checks and is why I use them.  I have also found that hard-cast plain based bullets, driven fast, do not lead my bores in either my 357s or 44 mags but the use of gas-checks works best for me. 

Kennisondan:  Yes, for best accuarcy you should slug your bore and make or purchase cast bullets to size.  I don't understand what you mean about tuning a gun to more standard dimensions unless you mean assuring the consistency of your chamber throats or cutting your forcing cone to about 11 degrees as some do but I do not think one eliminates the need for the other.  I would try the properly sized slug route first.  I have found it is best to take things like this one step at a time - that way there is less confusion as to what works and what may not. 

HTH.  Mikey.

[Graybeard]

I've owned a pile of guns. I've not really kept a proper record of the number but handguns alone I'd guess the number to exceed 200 by a fair bit. ALL have been used with cast bullets at some point in some quantity even the semiautos. I don't recall one single one of them that ever leaded to an extent that was of a concern to me or that affected accuracy.

Now you gotta realize I'm NOT a Ruger fan and what few I've owned haven't been shot all that much before getting moved on down the road so that "might" play a part in the results I've had. Most everyone I know and shoot with who own Ruger guns have had leading problems.

It is also true I'm a big fan of gas checked bullets and do use them heavily but not exclusively. I've used soft swaged mostly pure lead, super hard cast commercial bullets even those with bevel bases and my own cast of mostly linotype as well as those using wheel weights and various combinations.

Most of the revolvers have been S&W but in the mix have been FA83/97, Taurus, Colt Clones, Rugers, Colts, Rossi, Dan Wesson and likely others I'm not thinking of at the moment.

I'm not sure just why leading has just never been an issue for me but that's the case. I'm notorious for not spending much time keeping my guns clean especially the barrels. I clean them when they tell me they need it only for the most part other than wiping down the outside to keep down rust. Revolver barrels seldom get much attention from me. Sure when I do get around to cleaning one there is a bit of lead that comes out but never enough to be of concern and never so far for me at least enough to adversely affect accuracy.

In my S&W guns it's not unusual to see me firing a few hundred rounds in one day down the barrel and as I said I've yet to own one that leaded enough to affect accuracy. Not sure what if anything this has to do with any of the discussion to this point other than to say I have darn little advice to folks regarding leading cuz I've just not been bothered by it. Maybe you should rethink the brand of guns you use. 

[Lloyd Smale]

Bill im kind of with you on this. Ive had very little problems with leading. Mostly because like i said if a gun wasnt quite right i made it that way before i even shot it. Most guns will do fine even a little out of spec and guns that do lead badly are usually going to lead badly no matter what alloy or bullet design you use. If your bore is rough or your bullet is being damaged by the forcing cone or cylinder to barrlel alignment or by improper cylinder throat size even a gas check isnt going to totaly cure it and even if it did most likely the gun isnt going to shoot that well anyway. Ive never seen a case where a very accurate gun leaded. I think any over the counter factory gun should be checked for throat size obvious barrel quality and forcing cone quality and at least take a look down the barrel with a flashlight and make sure there is no obvious missalignment between the barrel and the cylinders. It doesnt cost a fourtune to fix these problems.  A guy can lap the barrel himself if its rough or has a restirction. A rough or poorly cut forcing cone or chamber thats rough or out of spec can be fixed usually for under 50 dollars by a good gunsmith. Guns like rugers and even smiths are mass produced by machines and are not individually measured for these things and for the bargin prices we get them at cant be expected to be. Ive picked up a couple real bargins in my life by guys who claimed they had a gun and just couldnt get it to shoot and for a 50 dollar investment in tuning ended up with a tack driver. Cast bullets for the most part arent as forgiving as jacketed in an out of spec gun and theres very few over the counter handguns that dont need a tweek of some kind. Id say that more ruger then not come with cylinders that could stand to be recut to proper dimentions if using cast bullets and a good many of them can benifit from barrel lapping to remove constrictions. Ive dont even fool with them anymore. As a matter of fact i rarely measure them. I just lap them when there new and sent the cylinder out and for a whopping 30 dollars make sure its right for the size bullet i want to shoot out of it. It saves alot of time in load developement and with the price of bullets powder primers and lead anymore it usually is cheaper in the long run. Ive allway said i wont tolarate any gun that isnt in spec or has a crappy trigger. I just dont have the time to try to fight a gun like that on the bench. Sure you can try 50 different loads and 4 different bullets sizes and 4 different alloys and maybe find something that works by spending many hours trial and error but why? Dump a couple hunded bucks into it get it right get the trigger right and the gun will give you so much more confidence in it and yourself that you will no doubt agree with me that it was the best money you ever spent.

[Racer X]

What are the ideal dimensional relationships between throats, bullet and groove diameter?

I have heard conflicting opinions from both custom revolversmiths and the cast bullet makers.

For example, for my 45 Blackhawk, revolversmiths recommend .453 throats for .452 bullets while the bullet makers recommend .452 throats for .452 bullets. The bullet makers even say my leading problems are coming from shooting cast bullets .001" under throat diameter. Some bullet makers even recommend shooting bullets .001" or more OVER throat diameter, which flies in the face of the theory that bullets must be smaller than the than the throats.

[Graybeard]

Throats 1/2 of a thousandth over bullet is about perfect. Bore just needs to be same or a bit smaller than bullet unless your bullet hardness/pressure is such that it obturates. Best not to depend on obturation and just have them all match closely as mentioned.

[Lloyd Smale]

another point bill kind of accidently hit on is cleaning barrels of cast bullet shooting revolvers. I dont shoot jacketed so what comment on them but its a rare time that i will put a brush to a handgun barrel. I was taught years ago that a handgun barrel shooting cast gets seasoned by the lube just as a cast iron skillet get seasoned and a clean barrel wont even settle down and shoot to it best until it gets at least 50 rounds through it after cleaning. Ive got guns that have thousands of rounds through them and the barrel has never been touched. Cast bullet rifle competitive shooters will agree with this and allways go to a match with a seasoned barrel. Even something as minor as switching lubes can change things and requires rounds to season the barrel to the lube your using. Ive proven it right myself. So if you are shooting groups with a new gun keep it in mind. You might discount so groups in load developement that will actually be cut in half in size once you get a few rounds down the pipe. Ill clean a handgun barrel only when leading forces me too and again like bill said its a rare time that leading gets that bad in any of my guns. Some dont lead at all and a few will get a little leading and then level off and not get worse. I small ammount of leading in your barrel wont hurt anything. If it bothers you a few jacketed bullets or even gas checked cast bullets will usually blow it out.

[Racer X]

Throats 1/2 of a thousandth over bullet is about perfect. Bore just needs to be same or a bit smaller than bullet unless your bullet hardness/pressure is such that it obturates. Best not to depend on obturation and just have them all match closely as mentioned.

Then are throats that are a full .001" over bullet diameter too big and will cause leading?

[Graybeard]

Might. Might not but that's NOT what I said. I said that 1/2 thousandth is about ideal. Didn't say that just because it's .001" over that it will lead. Hell it might or might not even at 002" over. You'll never know until you shoot it with your bullets.