What is Lube's Purpose: Does Lube Seal?

[Pop Gun]

I decided to run an experiment. I tried to be open minded about the function of a lube with the test squewed towards looking at lube as a sealent.

If lube does perform a seal function, that would infer that a seal function was necessary or desireable. It should raise pressure. Since pressure is proportional to velocity, it should also show a velocity increase as the seal improves. So I thought for awhile and I decided to consult an expert, Mr Gun.

I spent all day with a Rem 30-06 and I selected two bullets. One lead and the other a Barnes tripple shock with the lube grooves. (See what's coming huh?) I held pressures that Quickload predicted at between 34k and 41k using RL15. This was so we were not out of the accepted practical range for either bullet and just in case the seal did raise pressure, I wanted to be safe. And I figured that if I kept the pressure down on a "hard" bullet, that low pressure would be very difficult to get the bullet to obturate and any pressure / velocity increase could be atributed solely to the lube.

So in essence, I was giving the lube every opportunity to .... seal.

I shot the lead bullet with LBT Blue. I shot the tripple shock dry for 5 rounds. Then I cleaned the gun and then I applied plain beez wax on that bullet using the same powder charge for all bullets . My logic here was to minimize any friction reduction and just look at "seal". In theory, the first shot should be the slowest and velocity increase as the lube built up and "sealed".

At the end of my testing, all bullets showed the highest velocity / pressure with the first round out of a clean barrel. As the lube built up in the bore (with the bullets that had lube and started to .... seal) the velocity dropped. The Barnes solid copper bullet, dropped velocity also. So seal was evidently a non-factor as pressure / velocity dropped.

In fact, the dry bullet that used only powder fouling for lube, and we know that powder fouling leaves air gaps between the carbon granules that would "prevent" a theoretical seal, ( I picked a slower powder just for this purpose) maintained the highest velocity showing the smallest extreme spread after five shots.

While the theory of lube as a sealer sounds plausible, it is very misleading. Just because it is there is not a good justification in my mind. I would say that lube acted more like a bore fouling that the bullet had to deal with than any sealent, slowing bullets down. And this could be why using only enough lube to prevent leading from friction reduction achieves the best results both with accuracy and velocity. Maybe the fouling part of the lube equasion is also why you get different velocity levels as you change lube and hold the powder charge steady.

So for me lube is still a necesary evil for cast that performs functions in this order.

1. Friction reduction
2. Minimize bore fouling in the temperature zone that it is operated
3. Keep powder fouling soft between shots / outings

Realize the many ingredients that have been used as lubricant over the centuries from cloth to bear grease to water pump lube to the stuff we use today most of which has a bees wax base and ask yourself which one of those ingredients would be the best sealent?

If you want to add seal to this list, you can place it where you feel comfortable.

[carpetman]

Pop Gun---Your thinking that lube really doesn't seal is pretty much along the lines of what I think. Why do I think that? Several reasons. First off,take your hardest alloy---blend in whatever--heat treat it and quench with ice from a glacier or whatever else to make it hard. Now hit it with a sledge hammer as hard as you can. Did you get flatteneing? Yip. How many footpounds was that? I don't know,but it wasnt the several thousand pounds of pressure you get when you shoot it--not nearly. Does lead forced against a gunbarrel seal? If not we are in trouble with all the solder joints used in plumbing----they would all be leaking. Ever notice you can have a leak on an air compressor system someplace and when you first turn on the compressor it may not be leaking--but starts leaking as the pressure builds? Same with a faulty water system,you can blow as hard as you possibly can and it seems airtight but when you put pressure to it it leaks. In those two examples we are not putting nearly the pressure on things as you do when a gun is fired. That base is going to expand---think they call it obturation or some such. The lube is ahead of the base of the bullet and I think the base of bullet is forming the seal. For the lube to be forming a seal I would think it would have to become liquid and if that were the case all the lube would be spun off either in the barrel or outside the barrel,yet recover a bullet and it still has lube---almost as much as it started with. When metal is stuck together and you can get a little penetrating oil on it,they become unstuck--if lube was a sealant would seem they would be stuck tighter.

[Bret4207]

Oh lord- this one is gonna be worth watching! There should be some good stuff here by Monday morning.

My thoughts- I can see some guys bracing themselves already- As a friction reducer I agree. I think as the lube is forced out of the grooves by obturation and rotation there is some lube filling the imperfections in the barrel and easing the way for the next boolit.

Fouling? I suppose the fresh lube has certain solvents in it that would soften old lube and powder fouling to an extent. I would also suppose the fouling will be riding on a layer of lube if there's enough of it and that will make life easier too.

Sealing- I was thinking about this the other night doing chores. If, and it's a big IF, a booilt fits the throat and is slightly oversize for the bore then the lube should have no where to go as the boolit starts down the barrel. At least until it's forced out of the lube grooves or the initial pressure drops to the point it's not forced out and the rotation either isn't enough to spin the lube out or we just plain run out of lube. I'm not sure if I made that clear, but if my theory is close to right then the lube would act as a part of the seal provided by the slightly oversize boolit. It should therefore at least contribute to maintaining good ignition, one of our chief aims, and consistancy between shots.

Now you didn't state whether it was a gas check design or not, but I'm assuming it was. That little copper alloy cup makes a big difference to barrel condition. Whether you think of it as a seal or a scraper or both it adds to the mix. I also wonder if we aren't comparing apples to washing machines here. How we test a booilt against a bullet is a tricky and subjective thing. The Barnes isn't oversize, or I wouldn't think so anyway, so the bullet isn't as much a part of the seal like the it is with the lead alloy booilt. There isn't near the lube groove on the Barnes from the pics I've seen and there are probably other dissimilarities I'm overlooking.

I'm not disagreeing with any of your conclusions. I'm just wondering out loud.

[44man]

Very nice and I'm glad you took the time for the test. That has been the way I felt about it all along. In my humble opinion, the boolit/bullet is the seal, always has been and always will.
About bees wax and why it the best is because it mixes readily with almost anything and is easy to adjust the viscosity with as well as being a lube in it's own right. It is also fairly cheap compared to some like bayberry wax, etc.
I have a pile of moulds, many that I make myself, with all sizes and amounts of grease grooves. Since I shoot mostly revolvers, I can't talk much for the rifle shooter, but I have experimented with leaving a GG empty and then getting as much lube on a boolit as I can. I have never seen any difference in my accuracy. I find a slight difference in boolit design much more important. This is still a total mystery to me as to why one boolit shoots super and one that looks almost the same, with the same quantity of lube carrying capacity and just a slight difference in size and placement of drive bands, can shoot poorly and needs a different powder charge.
Designing a boolit smacks of magic and voodoo where a boolit doll needs to be stuck with pins. Sometimes when I am cutting a cherry, I say, I'll just cut a groove here! The darn thing will work!
Please, nobody ask me what works because it is where the pin sticks the doll.

[carpetman]

Tpr Brett---Sealing adds to ignition consistency? You lost me there. Another thought about sealing: ever shoot a bb in a pea shooter? Can be done and there is no seal---remember we don't have enough pressure with our mouth to even air up a tire to 30 psi and guns are creating thousands of pounds of pressure..

[45 2.1]

Another thought about sealing: ever shoot a bb in a pea shooter? Can be done and there is no seal---remember we don't have enough pressure with our mouth to even air up a tire to 30 psi and guns are creating thousands of pounds of pressure..

Lung air pressure when blowing amounts to about 2 psi when measured.

[Pop Gun]

1. Fouling? I suppose the fresh lube has certain solvents in it that would soften old lube and powder fouling to an extent. I would also suppose the fouling will be riding on a layer of lube if there's enough of it and that will make life easier too.

2. Now you didn't state whether it was a gas check design or not, but I'm assuming it was. That little copper alloy cup makes a big difference to barrel condition. Whether you think of it as a seal or a scraper or both it adds to the mix.

3. I also wonder if we aren't comparing apples to washing machines here. How we test a booilt against a bullet is a tricky and subjective thing.

4. The Barnes isn't oversize, or I wouldn't think so anyway, so the bullet isn't as much a part of the seal like the it is with the lead alloy booilt.

5. There isn't near the lube groove on the Barnes from the pics I've seen and there are probably other dissimilarities I'm overlooking.

6. I'm not disagreeing with any of your conclusions. I'm just wondering out loud.


Bret,

1. Anyone shooting black powder knows the importance of keeping that fouling soft. When in battles with BP, guys carried different diameter balls for use when they didn't have time to clean. As they shot, lead got smaller. And with smokeless, if you set a rifle up for a couple of weeks, you don't want that rock hard when you get back to it.

2. Bullet was in fact a GC and it was checked.

3. Best test I could come with. Your task is to find holes in my process because Professor Gun can't be argued with unless you get another Professor Gun.

4. This was the KEY. If it could be realized that a Barnes Bullet of solid copper would not obturate as much, then any possible seal improvement could point to the lube which it did not.

5. All bullets were 165 grain. My lead design has grooves comparable in size to the Barnes.

6. Please do. While this board has never been tilted toward theory and maintains "how to" as it's mantra, it has always been blessed with the desire to weed out Old Wives Tales. And this is a New Wives Tale that our generation is trying to start. The ol time smokeless / lead shooters believed that lube was a fouling. They got away from olgival designs and placed a sharp shoulder on every bullet. Some designs even added what was called a clean out groove. This was so that the bullet could scrape all that funk out ahead of it down to bare metal so that a bullet could maintain a seal and maximum depth for the rifling to grab hold of. So they wanted that sealent out of the bullet's path. Each bullet was supposed to prevent it's own leading.

Look at factory molds charts up to 1980 and you won't be able to find a true olgival design anywhere. Even bullets that looked like olgivals had a shoulder for fouling removal. Not until Veral "re-invented" the olgival design did we "think" we discovered something all over again.

One other point about seal. And this was with the Barnes bullet. You don't get gas cutting on a Copper bullet. But it does atomize the copper and blow it ahead of the bullet. As the bullet passes over it, it is ironed onto the bore and becomes coppering. This is how the experts claim coppering happens.

If the lube sealed as we like to believe, I would have had no coppering in my throat because gas couldn't get passed it. Right? I had copper. In fact, I took a bore scope and looked and the coper was just as bad after 5 shots with the lubed bullets as it was without it. But down the bore the lube did act as a lubricant and minimized some coppering. That is a visual guestimation on my part of coarse.

[DLCTEX]

Back in the era before chromed piston rings we put oil on top of the pistons of an overhauled engine to seal the rings and increase compression. Whether it be from filling imperfections in the metal or creating a lip seal, I think it's effect cannot be discounted.

[Bret4207]

Uncle Ray- Consistancy- My thought is a well sealed bore, whatever the cause of the seal, will promote better ignition than one where the bore is sometimes sealed and sometimes not. The closer we get to the same specs or every shot the better it should be, right? A liquid an't compress and the lube is a "liquid" under pressure so it should seal to an extent.

"Look at factory molds charts up to 1980 and you won't be able to find a true olgival design anywhere. Even bullets that looked like olgivals had a shoulder for fouling removal. Not until Veral "re-invented" the olgival design did we "think" we discovered something all over again."

Gotta go back a ways to the early days of Belding and Mull. Verals ogival designs look an awful lot like the old B+M designs. Check out Keiths "Sixguns" and "Sixgun cartridges and loads' for some pics.

No disagreement with anyone. As I said, this should produce some good posts.

[Doughty]

Pop Gun

When I had the time yesterday, I tried to think of a good test that I could make in an attempt to prove or disprove this theory. I have not been able to come up with one as yet. I appreciate the testing you have done and your posting of your results. I am going to be away for awhile. While I am gone, I hope to have time to think more on this subject, and perhaps do some testing of my own, when I return. Also hope to hear about what others have to say on the subject.

I really like this place.

[DLCTEX]

Pop Gun said " you don't get gas cutting on a copper bullet. But it does atomize the copper and blow it ahead of the bullet." That sounds like gas cutting to me, just maybe the effects are less pronounced than with lead.:-D

[9.3X62AL]

I tend to agree with Dale's idea, using his parallel to piston rings/cylinder wall and the effects of oiling upon compression seal--both to increase compression capability and prevention of blow-by gases.

Do I have PROOF of this? Not really. The late Walt Melander had a belief that barrel leading was caused by the same conditions given above for copper fouling......blow-by gases acting like a cutting torch, atomizing metal and depositing it on the bore surface to be ironed into place by the boolit passing over the deposits, with deposits building up as firing continued.

BELIEF is about all I can up with, and I believe that "lube" can do three things--

1) Provide a bit of sealing, as in the example of a piston engine.

2) Provide a bit of lubrication, a sort of ablative coating that reduces friction a little.

3) Soften powder fouling.

I also think that without well-fitted boolits, the slight but nonethless vital-to-accuracy effects of lube are largely wasted, just as in the piston engine where loose/worn rings won't seal. SAE 50 oil won't take up much slack when the rings are shot, and thickened boolit lube won't improve bore sealing with an undersized boolit. Boolit dimensions--boolit metallurgy--boolit lube, in descending order of importance--that is my belief, and like much of the rest of my life--is rather unscientific. I'm always open to new insights, though--so I look forward to seeing more info on this thread!

[felix]

Yep, gas cutting is not theory, but fact. If it happens every time, or in our situation enough to be significant, it's fact. Lubing, oiling the bore in advance will give something for the plasma to adhere to instead of to the barrel. Sooner or later the barrel will have to be cleaned, even after shooting very soft loads. Left over lube, even if no plasma to speak of, will get hard as the barrel (as seen by the boolit) and force a boolit to become too small for the remaining of the barrel. Time to clean when the accuracy is no longer acceptable. ... felix

[frank505]

we are beginning to think that in the 500 Linebaugh with a 450 Keith bullet and Wc 820, gas cutting is starting before the bullet has left the case. Try catching some triple shocks at long range so the deformation is lessened, both dry and lubricated with rooster hvr. I will try that this winter in a 308 scout, both dry and lubed. Remember a molyed bullet shows less deformation than a dry one. Why???

[44man]

Dale, I had one of the best automotive teachers at West Tech High School back in the 50's. The reason to put a lot of oil above the piston was for initial lubrication so the cast iron rings would not score the newly lapped cylinder. This is also done with chrome rings, they did not protect a dry cylinder! Either type of ring will make the engine smoke (Where is the seal?) until the rings are worn to a perfect fit in the cylinder which takes a minimum of 500 miles of easy driving. Chrome rings took longer! This is not like a new engine today that can be run full out because of extremely precision fit parts, like a good fitting boolit!
Now if we are taking a compression test with a dry cylinder and then take another with oil in it, it will read higher. But this is with only the starter motor turning the engine. If you crank it long enough, the compression rapidly drops off to the dry cylinder condition and is why only so many cycles are used for the test. The oil quickly blows or leaks past the piston. This increase in compression is not there when pressure rises from the engine firing. Oil does not seal under pressure. The oil allows the rings to flex in and out of the piston grooves and follow the cylinder walls. The oil does fill microscopic pores in the metals to provide lubrication but does not seal any gaps like a score on the wall or a nick on a ring. Yes, making the oil thicker and thicker will aid filling scores but you will destroy the rest of the engine. Kind of like the old practice of pouring sawdust in the tranny before selling the car.
The moly coated bullet is so slippery that it moves before deforming. But the darn stuff will build up in the bore and is hell to remove. Lubrication, lubrication, then fouling! Most likely why I never have luck with LLA because the fouling gets worse. A plus with ill fitting boolits when the bore gets smaller. Works fine on pitted barrels too.

[felix]

Car engines are getting better because they are using metals (alloys) that do not expand/contract as much, and therefore CAN be fitted more closely! Gosh, it has taken years for the car arena to get up to this "quality", while the quality has been there in the jet engine business for eons. Probably limited supplies of the exotic metals (alloys) is the reason, but using a higher percentage silicon in alloys is cheaply done and works in the lower demands of a car engine. 200K miles versus 65K miles of yesteryear. The car bodies fall apart faster than the drive train nowadays. Electric motors with ceramic bearings will last 1M miles. Can't wait for the car bodies to catch up. Did I ever mention that I hate cars with a passion? ... felix

[fecmech]

I think a quite simple test will tell if lube acts as a seal as I believe it does. Shoot some plain base bullets with lube and some without into the snow this winter. See if the gas cutting extends passed the lube grooves on the unlubed bullets.
I have recovered such bullets in the past where gas cutting went into the lube groove and then on to the next drive band (talking peestols here). This was at a time when I loaded bullets that sometimes did not have the lube groove filled all the way around. I doubt I have any laying around to post now as we were getting ready to move last year and I cleaned up a lot of odds and ends but I'll look and see. If not I'll shoot some this winter and post the results. Nick

[frank505]

I have some multi lube groove bullets that exhibit gas cutting on the bullets shank way above the base but below the crimp. It is very educational to recover bullets in snow, maybe we will get some this winter. Otherwise I will use sandy hillsides and learn how to post a picture.

[carpetman]

I agree with 44man that the oil on top of a new overhaul is not for a seal but for lube. I have seen newly overhauled engines the starter would not even turn them over---lots of friction. They need all the help they can get for the initial start. That much friction should be making a seal. If the oil were sealing things,why would the seal not be lost when the engine starts and the oil gets burned away? Why would chrome rings not need the oil,maybe less friction? I never tried putting a head back on a broke in engine without the oil---force of habit. But I bet on a broke in engine it is not needed?

[BABore]

Any thoughts on the hydraulics going on?

If you have a decent bore and bullet fit, the driving bands are in more or less full contact. When force is applied to the bullet's base you get compressive force. The bands are being forced towards the bore shortening the bullet. The lube between the bands is under tremendous hydraulic pressure. With all things being perfect it has no place to go. Does anyone know the compressability of the lubes we use? Are they like water or hydraulic fluid? I don't have a clue. If they behave like water or HD fluid, then you have an basic seal with the bullet bands and a secondary seal with the lube.

I'm probably not making too much sense cause I have this picture in my mind of Bob with lips on a tire pressure gauge trying to read the numbers. :bigsmyl2:

"Lung air pressure when blowing amounts to about 2 psi when measured."

[44man]

A poor fitting boolit will gas cut past the lube grooves which shows the lube did not seal the gas off. Kind of silly to think grease works better then the lead!

Felix, the new alloys used in engines really does the job and the best part is the super good air cleaners do not let the dirt in to cause wear. Add to this the detergent oils that keep gunk in suspension so the better oil filters can remove it and the PCV valve that rids the crankcase of more gunk. Then the computers that control fuel and timing so extra fuel is not diluting oil in the cylinders. Many things come together to make engines last longer. I have an old Toyota with 300,000 miles that runs like a champ, doesn't burn any oil but is rusting away to a pile of dust.
If any of you fly RC model planes, there are ABC engines with no rings on the pistons. Aluminum, brass, chrome. I don't like them because they have to run lean and hot or they seize. The metals expand at the same rates so there is no gap for leakage. Cool any and the metals contact each other with an instant stop. A dead stick landing is no fun if you are not near the field.

[fecmech]

[QUOTE=44man;110017]A poor fitting boolit will gas cut past the lube grooves which shows the lube did not seal the gas off. Kind of silly to think grease works better then the lead!

I agree with what you say in regards to a "poor fitting bullet" but that's not what Iwas proposing as a test. My idea for a test is a properly fitted bullet with lube and one without. I believe that will tell the tale. I will do the test myself this winter and post results whatever they may be. Nick

[DLCTEX]

The comment about chrome piston rings comes from our experience with Ford Tractors in our shop in the late 50's when chrome rings were first introduced in the tractor repair kits. We were unable to get the rings to seat, even after several times of replacing sleeves, pistons and rings. Ford sent a factory rep. to find the problem. He had us install the parts as he watched. When he saw me dip the piston and rings into a pan of oil before putting the ring compressor on, He said, "there's your problem, if you oil these chrome rings like that, they'll never seat'. We began putting the rings in dry and had no more problems .

[DLCTEX]

I have read it several times and still don't get the point. You can blow the BB out, but the efficiency is less than if you blew it out of a '177 cal. tube where there would be a better seal. If you air up a cartridge case to 2 psi., the BB will not go far. If you use a slow powder, I mean a lung full of air, the results will be more satisfactory without danger of bursting the paper tube as might be the case using an air compressor. I used to install boat lifts that used 8 psi to lift thousands of pounds clear of the water, just took a little time to push the water out of the tanks. Dale

[44man]

Dale, yup, chrome rings were hard to break in. We still used oil on cars. Took a long time to stop smoking but driving miles on the road is different then the use a tractor gets where use is measured in hours. Ford used some tough rings on them things. But you can see my point that the oil did not make any kind of a seal. In fact it prevented a seal.

[Lloyd Smale]

I kind of go with franks idea on gas cutting i think a majority of it happens as the bullet leaves the case when the case opens up in the chamber to allow it to release and that chamber dimentions have the biggest play in it. Once it starts its going to continue down the barrel and cause leading. A good lube will help as it somewhat seals the impefections in the barrel and bullet as it goes down the rifling and It also no doubt acts as a lubricant and puts down a layer of i guess what you could call fouling that gives consistancy to the load and puts a barrier down between the bullet and the rifling that keeps the lead from sticking. I would guess, and thats what im doing because i sure am not a scientist or a ballistics expert. That it also seasons the barrel in the same what you would season a cast iron skillet as i know from testing a theroy John linebaugh preaches that a cast bullet handgun doesnt show its best accuracy till you get about 100 rounds of cast threw it and if you change lubes you need to shoot another 100 or so before it will settle in to that lube. In my testing this has held up and is the main reason that i will rarely clean a handgun barrel anymore and make my lubes in big batches. I have to chuckle when guys do accuracy comparisons with different lubes and shoot maybe three or four groups and claim one is better then the other. It just doesnt work that way in my experience. If i was going to test a lube for accuracy id clean my barrel throughly shoot a hundred rounds plinking and then sit down on the bench with it. Frank i have a lot of respect for your opinion on this and am curious as to whether your testing has mirrored mine in any way. The problem with this whole deal is every gun is its own animal and fouls leads and has different dimentions and reacts to changes in alloys lubes and loads differently and different guns like different lubes just like they like different powders and primers and thats why theres so many opinions on it. Whos right? Hell i dont know! better men then me cant explain it.

[castalott]

I 'seem' to remember that the reason soap cleans is that it reduces surface tension and the dirt or whatever won't cling to anything. This may not be the exact function of lube in the bore, but I 'think' there is something similiar going on. I can't explain how the very first shot with a perfectly clean bore doesn't lead immediately unless some lube is blown forward of the bullet as it leaves the case.

Maybe breach seat identical bullets so the seal is in place and then vary the lube for testing.

[Cliff]

I remember reading something along this line some years back by General Julian Hatcher, not certain. They found bullet lubes are actually a contaminate in the barrel and unlubed lead bullets shot best. But the bullets were made to fit the bores exactly. It was explained the purpose of bullet lube was to prevent lead from being deposited in a barrel by vaporizing before the lead which is being hit with blow by could do its worse. He did experiment with placing the lube behind a bullet, IIRC he use white lithium grease, between the powder and the bullet base, just a little dap worked very well. However could not get consistant accuracy as the lube still built up in the barrel and when it was purged out it threw the shot off on the target. However they didn't get leading. I think this was also talked or written up in the Cast Bullet Association's journal "Fouling Shot" sometime in the past. The initial testing was done by the NRA. The Lube is not meant to seal the bore rather this is accomplished by proper bullet fit to the barrel. Just my thoughts on it. Good Luck.

[ammohead]

Ok, I'll give it a shot.

The surface of a bullet is round. Whether at the groove diameter or in the lube groove. The inside of a barrel is not because of the grooves cut to impart spin on the bullet to aid accuracy. Somehow, in a fraction of a second, the bullet must go from round to rifled and maintain its form and concentricity for balanced flight.

Many press forming processes in manufacturing work better with a film of lube on the material to be worked. Most materials will resist being reformed using pure pressure. The lube assists the material to conform to the new shape that the manufacturer desires.

It has already been stated that an unlubed bullet has the potential to be more accurate than lubed ones because there is nothing else to cause deforming of the bullet, but that leading often is the result. In this case the leading is being caused by friction because there is nothing between the alloy of the bullet and the steel of the barrel. Only under ideal conditions will no-leading occur here. Something is needed to prevent the contact between lead and steel. This is what lube does.

If only on a molecular level it keeps the steel and lead apart. The rifling, as well as obturation, displaces the lube in a hydraulic action that distributes it to where it is needed. It also lubricates the reforming of the lead alloy to the new form that the barrel imparts on it so that the alloy can assimilate the new contour perfectly. This mirror image assimilation is what provides the seal. It is also why good barrels shoot better than worn, rusted, or poorly made barrels. With an inferior barrel the form that the bullet is being forced to assimilate is inconsistant and the alloy of the bullet is not capable of repeatedly changing its form enough to match the barrel and a quality seal is unobtainable. The inconsistant surface of the barrel also makes it harder for the lube to maintain its microscopic separation of lead and steel.

Comparing the needs of an alloy bullet to a piston and cylinder of an engine IS like apples and washing machines. In an engine both components are as round as manufacturing tolerances will allow. In addition both surfaces are quite similar in hardness. Add in that the axis of the bore of an engine is rarely even twice the diameter. Not the same things going on at all.

Gas checks, I am sure do some sealing on their own, and maybe they scape away some gunk. But I am convinced that the biggest plus they provide is grabbing the ass-end of the bullet with a vise grip applied by the rifling, assuring that it rotates exactly at the same rate as the rifling with no slippage whatsoever thereby guaranteeing a tighter seal.

In summary, the lube in and of itself does not seal. It is not strong enough. What it does, is assist the alloy in creating the best fit for sealing that can be achieved.

This is fun stuff!

ammohead

[twoworms]

Here is a good read on boolite lube.

http://www.lasc.us/FryxellLubeCastBullets.htm

Tim

[carpetman]

ammohead--I think you are on to the problem. The bullet is round but the barrel has grooves. Easy fix. You have seen that spiraly licorice candy that has fins on it. Get the mold they use for that and just cut em to the length you want. Only need one mold per cal---length would determine weight. Want more weight go shorter or was it longer cant remember. BTW I shot some of that licorice candy to confirm this and got zero, nada,not one bit of leading---using no lube.

[KYCaster]

Ray: How many rounds till you reached a black bore condition?

Jerry

P.S. That must be a sweet shootin' rifle!