Lube Grooves As THE SOURCE Of Leading?

[Linstrum]

I am going to propose an additional sub-theory about how bullet lube works, based on this excellent article that was already posted and discussed here back a little over seven years ago in 2007.
http://www.lasc.us/FryxellLubeCastBullets.htm (http://www.lasc.us/FryxellLubeCastBullets.htm)


The article itself is by Glenn E. Fryxell, who I'm sure many of you recognize, and may be read at


http://castboolits.gunloads.com/showthread.php?17538-Head-scratcher-How-does-lube-work&highlight=boolit+definition (http://castboolits.gunloads.com/showthread.php?17538-Head-scratcher-How-does-lube-work&highlight=boolit+definition)


What I propose is that under some conditions we may not need quite so many LUBE GROOVES as we may think!


I don't propose that we dispense with lube grooves altogether, but having multiple lubrication grooves may actually promote leading under SOME conditions. What got me to thinking about this is that several years ago I required some 0.325" diameter projectiles for an 8mm 48 Yugo Mauser, and I machined several grooveless cavities in a home-made mold block. I did cover the boolits I cast with Lee Liquid Alox just fine and used about 13 grains Red Dot with the approximately 75, 125, and 150 grain projectiles I made, and had no difficulty with leading as I forecast I would! After shooting maybe 75 of my home-made rounds, which as I recall were quite accurate, afterward I changed over to using a 175 grain Lee 8mm rifle bullet mold and thought no more about my grooveless home-made boolits until now.


What I propose may be happening is that the presence of several lubrication grooves may be promoting bore leading by giving powder gases some edges to pass over and erode as the gases move into the spaces once occupied by the bullet lubricant before said lube was extruded out of the groove into the area just in front of the bullet.With my groove-less projectiles there were no grooves and edges for the gas to pass over and gas-cut, and is why shooting my rifle with my home-made projectiles did not lead the bore.


When the lube grooves are full of incompressible lubricant the powder gas can't move into the space, and the edges of the lube grooves are protected because the hot gas can't pass over them and erode the lead and milliseconds later deposit it inside the bore. If the bullet didn't have any lube grooves to begin with, then that would diminish any chance for the gases to pick up lead at all. But cast bullets need lubrication for heat transfer and sealing, so if cast bullets had ONE carefully designed lube groove up toward the nose where controlled gas flow (more like rapid seepage) could pickup and deposit the lubricant to the bore where it is needed, it may be a step toward controlling leading more effectively.


Another function of bullet lubricant that never gets mentioned is it acts as a heat transfer medium from the bullet to the barrel to pass heat from the bullet to the cooler barrel, and thereby help keep the low melting point projectile casting alloy from gas cutting and plastering the bore. Bullet lubricant is important, as is having a cast projectile that is about two thousandths of an inch larger than the groove diameter so the projectile makes good firm 100% contact and seals the powder gases well. Read Fryxell's article and consider what I have to say in its light, it is quite interesting.


rl1,236

[62chevy]

No lube groves in a rifle bullet and no leading. That blows everything I've read all apart. Now comes the question on how fast did he push them.

[45 2.1]

You can get away with a whole lot of things at velocities under 1,600 fps that you can't get away with as things go higher....... and that's a fact.

[44man]

I make my boolits with more grooves, at least two instead of one like a Keith, does not carry any more lube if weighed but accuracy increased two fold. I also shoot PB at pressures into the 50,000 psi ranges all day.
I do not believe in the seal theory at all, only the boolit itself making the seal with no skid past the base band. Inertia and centrifugal force is better explanation. if gas gets into lube grooves at all you are done and the lube sure will not seal that off. If gas pushes lube past the boolit, you are cutting lead also.
Heat transfer--NO.
Wetting and softening bore residue--YES. Sets the bore so the next shot cleans the bore.
I do not find lube in recovered boolits at all. Mine spins the boolit clean at muzzle exit and I have a lube ring on the muzzle. Only store bought boolits will have lube here and there and throws boolits out of balance.
Lead itself is a lube but will rub off on steel so a film of lube keeps direct contact away. Like Babbitt bearings need a film of oil. What happens to your crankshaft if you run out of oil. I look at boolits like bearings, not rings. Notice the pistons have a scraper ring or oil ring to scrape oil back into the crankcase just enough so the compression rings have minimum oil. Oil is not the seal, the rings are. Just as the boolit is the seal.
Seeing guys shoot bare boolits shows the lead can lube itself. But I will stay with lube!
Powder coating is a barrier and also makes a boolit fatter but I worry about a wear issue that has not had enough time to judge. My .44 has very close to 80,000 rounds with the bore slugging the same as new, groove is still .430". Only time with powder coating will tell.
Molly has not worked out well, seems to build in the bore and is the devil to remove.
Anyway, I will not be painting my boolits.
The other thing that bothers me is the compression of the center of the base to force the GG out. if true GG's on recovered boolits would be less deep and there would be a cup on the base. Mind fart!
Think as lube as a barrier between metals and just a plain old lube.
I remember when Ruger made the first stainless guns, all parts were the same alloy and they had galling problems, special stainless lubes came out but Ruger found to make each part a little different alloy and it cured the problems.
I go 3 years without running a rod down my bores, Keep the cylinders clean or operating parts, lube and go. If cast did not work we would not be here and there would be no cast boolit site.

[Harry O]

I use 13gr of Red Dot in several of my rifle for light, plinking loads. That load was passed around many years ago (maybe 40) as a load you could practice with. Regardless of the bullet or the rifle, it is very accurate and does not lead. I have never put a chrono on one, but I would guess it is in the 1,200 to 1,400fps range. It also works great for fireforming wildcats, which I have also done.

[44man]

I propose my boolits with more and smaller grooves have better balance. I made a mold with one Keith style groove and another with more grooves, exactly the same other wise but the one groove boolit refuses to shoot. I fill all grooves and have a coating of Felix on the sides and nose after sizing. I will use my thumbnail to remove excess but leave all else. I might call it a TL but the quality of the lube is the difference. I love lube. and what the heck is "LUBE PURGE". Can't happen in the bore and at the muzzle is what you want. Get it out of the boolit right quick. Too say just put lube in one groove is better, I can't buy that. Are you defining a difference between 1/8" groups and 1/4"? I can't buy anyone telling a difference.

[BAGTIC]

Why do revolver bullets so often have more lube grooves than pistol bullets even in calibers where the pistols frequently generate higher pressures and velocities?

[MT Gianni]

Why do revolver bullets so often have more lube grooves than pistol bullets even in calibers where the pistols frequently generate higher pressures and velocities?
A cylinder gives it more opportunities to purge lube and there are more alignment issues than in a pistol. Both of those need lubed to avoid eroding a boolit.

[44man]

I do not like a Keith as much as I used to because of the shoulder but just maybe the one, deep and long GG has a lot to do with it.
One groove did not work well on a WLN either. There is a mystery here I can't answer.
I shoot PB boolits from my .475 and .500 with 2 GG's and if there was lube purge at the gap, I sure see no lube there. I do have a grease ring on the muzzle. Recovered boolits are clean of lube.
I even made the boolits with narrow base bands of .080" despite all that say it must be stronger. Has not proven out at 50,000 psi. No deformation on my boolits recovered and no skid at the base band. I made a mistake with the .475 boolit and the base band but it worked so well I did the same on the .500. Stinking wrong boolits have hit steel at 500 meters better then I ever did with a rifle. Please don't tell me a WFN goes unstable since my boolits average an 80% meplat.
I listened to most here and said OH,OH when the cherry was done. I draw no boolit pictures, just cut the cherries by sight on the lathe. I plunge GG's where I think they should be. I file the ogive by hand as it spins. If you want dimensions, you need some of my boolits because I can't tell you a thing. My revolvers have done 1/2" groups or less at 100 yards if I hold right. Foolish luck on my part. My boolit designs are free, pay postage. Mold makers can have them. You might mention me but I want no money. My boolits need a BHN so don't complain if your dead soft fails.
The lesson I learned years ago is "do not follow", most is wrong.

[cajun shooter]

They have several reasons on why some bullets have too many lube grooves and others don't have enough and of the correct size.
There have been many articles written over the years about this subject. I believe that you can't say any bullet and lube will perform in every gun of that caliber the same. I have purchased many molds that are of more than one cavity which are not the same as the one next to it. I had one 6 cavity Lee that dropped 6 different bullets. That stopped me from using Lee molds.
I now have for the past 10 years used special order molds from custom mold makers and it has paid off.
I must also disagree with 44man on his statement that he does not believe in the seal theory. If you don't have obturation of the bullet in the bore, you will have leading.
The reason that there is so much different opinions on this subject is just as 44 Man did say and that is most people are comparing apples and oranges. If you are not using the same mould and gun to do your testing then the standards are different and can't be used against each other. You may have similar results but not exact.
A good example is the bullet that I designed off of the Lyman 42908 for the 44WCF. Over the years, Lyman made the lube grooves more shallow and the bands rounder which resulted in a lot less lube in the two grooves.
That worked fine for those who loaded the round with smokeless powder but caused great problems for the shooters who used BP to shoot the cartridge.
I contacted Tom at Accurate about 4-5 years ago and had him make the 43-210B mold for the BP shooters in SASS with the 44WCF. I use NASA lube or a private mix of my own and have never had any leading, ever.
The bullets are close but my design has square shoulders on the bands and deeper lube grooves resulting in more capacity.
We had a very long thread on Lube Grooves some years back, I'm sure it may be found via a search. Later David

[popper]

L.G. as the source of leading - I disagree. MG 336 30/30, RD boolit - PB (13 gr. Unique) or GC (32 gr. LeverE). Peanut butter lube (thick) or veggy oil (thin - a few drops in the grooves) No leading & good accuracy. No hydraulics in the L.G. with PC either. Hydraulics of stiff lube helps with the thin base band. The 336 is tight at the ends and loose in the middle which caused leading using LC hard lubed boolits. Junk blowby in the middle that gets deposited at the tight end. Alloy was 50/50 H.T. Roto high Sb/Pb with sulfur added. Same problem in 40SW, same alloy.

[44man]

Obturation has two meanings. One is to expand the undersize boolit to seal---BAD IDEA. the other is fit first. To obturate means SEAL. The boolit must do this without deformation.
BP NEEDS a LOT more lube so you can not compare it here. So much more fouling that needs kept soft.
I cut revolver boolit GG's 25 thousandths deep. Two carry as much or more then one groove.
I do not believe in the lube SEALING, only the boolit.
BP is different and SPG always gave out with 10" of barrel left dry and hard, could not push a patch through unless too wet. Only home made lubes left a grease ring on the muzzle.
You need more lube with BP so why bring it here?
One other thing, my loads have worked the exact same in every single gun of the same caliber and even better then my old guns. My friends will use nothing else. Use my boolit and my load and if you change anything, you are on your own.
I have one friend, Dave that I sold my SRH to. Every single time he comes over he has changed my loads. I shot pop cans at 200 yards with the gun. He wants my boolits but does not listen. He changes loads. I shoot my old gun and ask, "What did you do?" He says "I KNOW, I KNOW!
If your Ruger has good dimensions it is 100% false that my loads will not shoot and every single BFR will shoot my loads exactly the same.
My S&W loads shot from every single S&W gun too. I have never needed a different load for any make gun.

[texassako]

I don't think the number of lube grooves matters so much. I have shot 2 pretty big lube groove extremes in the same rifle with the 311467 and the 311331. 7 grooves vs. 1 groove. Neither leads in the 26" barrel, and I only lubed the bottom 3 grooves of the 311467. You only need one edge, the base, to be gas cut to get leading, and every bullet has a base.

[TXGunNut]

One problem I see with this theory is TL boolits and LLA. A few of my favorite hunting boolits are from Lee RD moulds and they seem to work totally different from conventional lube and lube grooves. I realize the TL system has it's limits but within these limits and often beyond I see no more than a trace of leading, often none at all.

[44man]

One problem I see with this theory is TL boolits and LLA. A few of my favorite hunting boolits are from Lee RD moulds and they seem to work totally different from conventional lube and lube grooves. I realize the TL system has it's limits but within these limits and often beyond I see no more than a trace of leading, often none at all.
The thing is not leading, it is accuracy. too many look for leading with no look at accuracy. I hate Alox because it never shot groups and I could care less about leading. I have shot hundreds of lubes and alloys without leading. Is that what you look for? I look for groups ONLY. Alox might have leaded my bores more then anything, Mule snot is better. Dip boolits in a fresh cow pie would work better.127084RD at 50 and 100 yards. Hit low so I aimed higher for the last shot. 3/4" at 50 and 1-1/4" at 100 until I aimed higher. Felix Lube On a RD. Nothing wrong with a TL. it is the lube you use. I have never found cat pee lubes worth the time But I do not watch boolits like slingshot balls either.

[TXGunNut]

I get good groups with some loads, others not so good. Lube is likely at least part of the problem. LLA seems to lose it's effectiveness as velocity increases and I'm moving towards conventional lube groove boolits for those situations.

[ericc]

Has anyone ever looked at the edge of the grooves as the source of leading. You basically have a decreasing radius (less mass) as you approach the sharp edge which allows the lead to reach higher temperatures in shorter amounts of time at the sharp point of the band.

We use the same trick to control burn rates of propellants. On an extruded rod type propellant grain it's always the edges that ignite first. Ball powder which doesn't have that edge is known to require a higher heat load to get the propellant burning.

As long as the driving/sealing band is wide enough you can put a radius on the edge and I think that would stop some leading. People must be doing this or have in the past?

Here is a very simple picture of the radius I'm talking about. Ignore the spacing etc, that's just a crude mock up I made in about 10 seconds.

127104

Eric