Square lube groove vs rounded - pros and cons

[DrCaveman]

Ive been trying to decide on new molds for several calibers i shoot and a few that i may begin shooting soon.

Of most concern to me are 357, 30-30, and 30-06. Lesser but still relevant are 45 colt and 44 mag.

I did some searching about this ageless debate, and found a few consistencies in peoples attitudes toward the different lube groove styles. Let's leave out lee tumble groove designs please.

General consensus i found was that:
-square lube groove molds dont drop boolits as readily as round
-square lube groove boolits hold lube better than round
-square lube groove boolits may shoot with better accuracy (debatable, or minimal)

While accuracy is always a goal of mine, i also appreciate ease of production and lube application. In fact until i get another 10-20k rounds under my belt i bet that i would not see the minor differences in accuracy between the two designs. I realize that it takes diligence and patience to become expert.

So that leaves my concern in the realm of ease of boolit production and ease of lube application.

I would be tumble, pan, dip, or hand lubing these boolits as i dont yet have a lubrisizer.

It seems to me that like so many questions people post here, it is largely a matter of personal preference. But i would appreciate some feedback on WHY individuals have tended toward one design over the other, and the differences they have seen while casting, and applying lube. Lube retention during handling is also important to me.

While you're at it, what lube is being used for the design you prefer?

Thanks, good shootin to you

[GP100man]

In my findings rifle/carbine shooters (traditional revolver rounds) prefer the square groove for the reason it holds more loobe than a round groove.

I`ve found no difference in the booilt dropping from the mold ,but as a initial clean up I cast a few & lap the cavitys before they go into production, it cleans any burrs that may be present.

Rifle molds I purchase the large version, 311041 for the 30-30 ,314299 for the Mosins.
Easier to go size down than up .

I know things are a bit ridiculous rite now but a loobesizer makes things easier/faster/less messy .

But will say some good shooting comes from unsized & hand/pan & tumble loobing.

Couple of vendors for loobes are : White Label Lubes & Randy Rat ,both are excellent sources if ya don`t make your own !

[Char-Gar]

Well there really is no such things as a bullet with square lube groove. When Elmer Keith first came up with his design, he had some turned from steel and sent them to a mold manufacturer (I forget which one). These did indeed have square lube grooves and the mold maker would not make them because it would be almost impossible to get them to fall from the mold, so a change was made with the upper and lower sides of the groove being at 45 degrees whereas a true square would be 90 degrees.

Somel time later, Lyman changed the design to added a rounded bottom, stating that this would be easier to fall from a mold. Elmer Keith threw a fit, said this reduced the amount of lube by 50% and recommended that people buy their molds from Hensley and Gibbs as they still made the flat bottom groove.

So, what we are left with are bullets with flat bottom grooves vs. bullet with round bottom grooves. As you have noted the debate rages on about this fairly minor difference.

I have cast and fired many thousand bullets of both types and you can't prove there is any difference in casting ease or accuracy by me. Still, if I were buying a mold for retail, and the price was the same I would go with the flat bottom lube groove..why? Just because, that is why.

[DrCaveman]

Char gar, thanks for the clarification. I have read a bunch about keith and some of his books, and honestly that learning was the source of my original question. Seems there must be some really good reasons he preferred the flat bottom (better yet square) but i did not glean that many from his writings.

Once again i am digging into the 'why' when i could just say OK and run with it.

Well, if it comes to one particular mold design that i find desirable vs another with the opposing style of lube groove, maybe it would be more productive to just ask people about their experiences with those molds.

Still, any more input is welcome

[texassako]

I have a .32 cal. rifle mold Tom at Accurate designed for me(Lyman #321317 with a flat nose) with as close to a truly square groove as I have. It kind of takes a rolling motion to get it to drop, and they like to sit in there until you tilt it way over. Big, square lube groove boolit that shoots great with tumble lube(basically, I am not even using the lube groove) with a grain more Leverevolution than I use with jacketed; so I don't think groove shape matters that much except for how it affects the design of the boolit itself as long as you have enough lube to get it out of the bore. Look at Lee's tumble lube groove designs and quite a few of them shoot well. I wonder what Keith would think of those?

[MtGun44]

Actually, I have seen a boolit cast from a really early Keith mold and I was very surprised to
see a LITERALLY square (90 degrees!) end on the lube groove. So some of the early ones
really were square. I don't think this lasted very long, as I have only seen one.

In any case, the flat bottomed groove designs may have an advantage that is not obvious.
I wonder if the long, smaller diam area of the boolit doesn't compress under the pressure
of launching and provide pressurization of the lube in the groove? This seems likely.

A round bottomed groove should compress less and may provide a bit less lubrication
pressure.

That said, I have both kinds of 429421 molds and both work pretty well, but I have had
a bit better luck with the square bottomed versions - MOST of the time.

Not a big deal, but if I am given a choice - I'll come down for more lube.

Bill

[turbo1889]

As far as lube capacity goes, for modern smokeless powder I have found that most boolit designs hold too much lube with the occasional exception. Now for BP loads that is a whole different world and I would heartily agree with Mr. Keith's thoughts on the matter.

As to the actual shape difference irrelevant of capacity something that no-one has mentioned so far is that with hard lubes that can become brittle with age the rounded lube groove is definitively inferior and the boolit is much more likely to loose its lube in storage and handling because the lube is much more easily knocked out of the groove once it gets a little old dry and brittle (how effective the lube would be anyway in this state is debatable of course) but it is also true that the lube is also more easily wiped out of a rounded bottom lube groove as well. Long story short for lube retention during storage and handling a square edge (not really square, sharp angle) lube groove especially one with a high depth to width ratio is much better for lube retention. Lube does seem to come out of the groove or not come out of the groove equally when fired through the bore with little regard for the shape of the groove, at least as far as I've seen. If you want the lube to stay in the groove until it is fired a square lube groove does that better then a rounded one.

Another thing, the sharper the outer edge of the lube groove the more likely it is to scrape crud out of the bore and the shallower the angle the more likely the crud won't get scraped out and instead cut a groove in the side of the driving band. That is something that becomes very obvious with BP cartridges and muzzle loaders.

[Char-Gar]

Char gar, thanks for the clarification. I have read a bunch about keith and some of his books, and honestly that learning was the source of my original question. Seems there must be some really good reasons he preferred the flat bottom (better yet square) but i did not glean that many from his writings.

Once again i am digging into the 'why' when i could just say OK and run with it.

Well, if it comes to one particular mold design that i find desirable vs another with the opposing style of lube groove, maybe it would be more productive to just ask people about their experiences with those molds.

Still, any more input is welcome

Elmer Keith made a significant contribution to shooting and hunting during his time. Since his death, he has almost achieved sainthood and miracles are thought to have been worked through his teachings. The hard fact is he was just a human being with all that goes along with that. He was never uncertain about anything he had done. His designs, suggestions and principals were always the best and he never entertained any thought otherwise and didn't appreciate others holding such views.

When Lyman decided to mess with his lube groove, he took umbrage with that. I doubt there was much behind that other than ego. True believers insist his original design was best, but others will say..not so much. I don't think there is anymore to this ongoing debate than just that.

[Shuz]

I have several 4C 429421 moulds. 3 are round groove, and one is square groove. I have never been able to detect any difference in accuracy based on the type of loob groove. Far more important is the overall as cast diameters. I've been thinking lately that maybe I otta be thinnin' the herd, so I'll entertain offers on two of the round groove designs that throw at least .431 diameter boolits and the one square groove that throws .430+.

[chboats]

From what I have read, as Mtgun44 stated, the square grove will compress and force the lube out into the barrel. When Keith designed the mold he did not have the lubes that we have today. He needed the extra lube. Today most boolits have more lube than is needed.

Carl

[frank505]

The "Keith" style molds we have designed have flat bottom and a little draft on the sides of the grease groove. The flat bottom grease groove will expand radially and that is what Elmer Keith knew and wanted. The round grooves will not do much of anything and hold less lube or
more properly, sealing grease.

[Oreo]

Round vs square capacity is a silly comparison. If more lube capacity is desired all that is needed is a wider or deeper groove. The real comparison needs to consider the whole boolit because a small change in the lube groove will change the forward/aft weight balance of the boolit, the length of the boolit (to keep the total weight the same), the size of the driving bands, etc. So, if we were to say hypothetically that this one particular boolit does not shoot as well with a round bottom groove, that is not saying that a very similar boolit can't be made with a round groove that does shoot as well or better. There's a lot that goes into it and changing one thing by definition changes everything else.

[leadman]

I can tell you with certainly the Group Buy Lee Makarov mold with the deep square bottomed lube groove is a pain to get to drop the boolits. It is not because it is a Lee mold either as the boolits come out of the mold easily with a pair of forceps. If the mold is held so one half faces down they fall out onto the other half merring them.
I had a square bottomed 429421 Dc and now have a round bottom 4C mold and I can tell no difference in accuracy and there is no leading with either.

[Oreo]

I wanted to add: It is best for accuracy if the boolit sheds all of the lube immediately upon exiting the muzzle. Consider that a groove that holds the lube better during handling will also hold the lube better upon muzzle exit. It's a give-and-take that needs to be considered along with lube choice.

[45 2.1]

Here we have a thread that has lots of opinions and little knowledge posted...... just like most of the others threads about the same thing in the past. Very very few folks take the time to find out what really does happen or why certain things were done in the past.

[turbo1889]

I wanted to add: It is best for accuracy if the boolit sheds all of the lube immediately upon exiting the muzzle. Consider that a groove that holds the lube better during handling will also hold the lube better upon muzzle exit. It's a give-and-take that needs to be considered along with lube choice.

Not in my experience, based upon retrieval of fired boolits and "lube star" on the muzzle or the lack there-of. Granted I don't have high speed photography of the boolit while it is exiting the barrel but from what I can tell square or round makes very little difference as to whether the lube sheds from the boolit upon exiting the muzzle or not. That appears to be mainly dependent on the lube itself. Although I do not know for sure, I think that is because of the centrifugal force due to the high rotation speed (that whole spinning boolit thing because of the rifling). Some hard lubes stay in the grooves all the way to the target almost regardless of the lube groove shape. Others (like "Speed Green") show no lube on recovered boolits and leave a "lube star" on the end of the muzzle also seemingly with little regard to lube groove shape.


Here we have a thread that has lots of opinions and little knowledge posted...... just like most of the others threads about the same thing in the past. Very very few folks take the time to find out what really does happen or why certain things were done in the past.

I agree that there is very little "hard evidence" that has been presented. Most likely due to the difficulty and expense in obtaining such "hard evidence" the best I can personally offer is "In My Experience" type information and that is probably all most other people can offer as well.

[Char-Gar]

s
Here we have a thread that has lots of opinions and little knowledge posted...... just like most of the others threads about the same thing in the past. Very very few folks take the time to find out what really does happen or why certain things were done in the past.

Taking a shot at those who try answer a fellow's question is not very helpful.

A careful and respectful answer by someone who really does know what happens and why certain things were done in the past would probably be received well and be helpful to boot.

But is such an answer were not backed up by through and complete scientific date and historical footnotes, it would likely be just another opinion based on somebody's experience passed off as fact.

[45 2.1]

I agree that there is very little "hard evidence" that has been presented. Most likely due to the difficulty and expense in obtaining such "hard evidence" the best I can personally offer is "In My Experience" type information and that is probably all most other people can offer as well.

A long time ago Catshooter contacted me and wanted to do a complete Keith GB from Lee. It took about 4 months to round up samples from original Keith molds from a few people that had them. I contributed the 454423 myself as I had an original. Those samples did not conform to what everyone now thinks is a Keith boolit. I spent a year... Yes, a full year learning what Keith knew about those designs, and why they worked. Shooting tests and a lot of lathe time duplicated those designs and performance plus a lot of boolit recovery. That influenced all my designs after that. What everyone thinks happens and what really happens are usually different things. The first Lyman handbook has an article of a couple of pages telling in Keiths own words his loads, lube, alloy etc. for his loads. Taking Keith's own words from his books and from the articles by Keith and Ross Seyfried (who learned from Keith) we have a pretty good picture of what he wanted and ended up with. The major problem is most everyone shoots too hard an alloy and too slippery/dense a lube besides the so called Keith designs now used. Rifles and high velocity enter another realm entirely.

[Char-Gar]

I don't think it is any deep dark secret, particularly to us grey heads, that Elmer Keith used a binary alloy of 1-16 (tin to lead) for his magnum sixgun bullets and the good old sticky Lyman/Ideal black bullet lube.

1-16 has a Brinell hardness of about eleven which is close to what I get with my batch of crimp on wheelweights. I still use a soft and sticky lube that requires no heater.

But the question was not what did Keith do, but about the rounds vs. flat bottom grease groove and is their any clear evidence on if better than another. I don't think that has been answered.

I have fired many Keith bullets including 358429. 452423, 454424 and 429421 of the original design coming from old unvented mold bocks as well as 358429, 452423 and 429421 late 60's vintage round groove molds. I have fired them from 1-16 and ACWW and lubed them with a variety of soft lubes including black sticky Lyman/Ideal of which I still have a goodly supply. This is pretty much an apples and apples comparison real Keith bullets, alloy and lube.

The bottom line is I have yet to detect any real, repeatable differences in lube groove design based on my shooting over 50 years with these bullets.

For the record: I cast my first Keith bullet (452423) in 1959, read everything Keith wrote, corresponded with him and even had the pleasure of spending a couple hours with him, Bill Jordon and a couple of others around a table drinking whisky and telling gun stories.

I don't think all of us are as ignorant, inexperienced and generally in the dark on the subject at hand, as some would make it seem.

[45 2.1]

Taking a shot at those who try answer a fellow's question is not very helpful.

I'll take your using your tag line there. I'm not. Some of us go a heck of a lot further into things than you believe possible. If you don't believe that then it's your problem..... not mine. Just yesterday one of the local board participants here came over with his 308, his cast boolits, powder and prepped cases. I showed him how I loaded his stuff and explained things to him, then we shot them up........... less than 1.25 MOA at 385 yards at about 2400 fps for group cores (from both of us several times). Nice hot day with 10 to 20 MPH shifting wind. Now read your last sentence again and see what it does for you. Showing him how is a lot better than telling him how.


A careful and respectful answer by someone who really does know what happens and why certain things were done in the past would probably be received well and be helpful to boot. But is such an answer were not backed up by through and complete scientific date and historical footnotes, it would likely be just another opinion based on somebody's experience passed off as fact.

Everybody chooses different equipment and ways to load. Such cannot be helped much until certain inadequacies are cured in their technique. BTDT several times here and posted some of their targets. Besides, I don't see anyone here doing much of that, including you.

[Char-Gar]

The question, which is being dodged, is round bottom vs. flat bottom lube grooves on Keith style bullets.

I am still looking for a body of knowledge to back up claims of undefined para-normal shooting feats. It is impossible to evaluate such claims, so they must be disregarded. Anecdotal accounts of who did what, fails to impress me or just about anybody else around here that has been painted as "uknowing". I am also unimpressed with cell phone pics of targets.

When somebody turns in this kind of performance in a registered Cast Bullet Association match with ten shot groups, witnesses and scores, I will pay attention, very close attention. In other words, I will believe it when it is printed in The Fouling Shot.

[45 2.1]

I don't think it is any deep dark secret, particularly to us grey heads, that Elmer Keith used a binary alloy of 1-16 (tin to lead) for his magnum sixgun bullets and the good old sticky Lyman/Ideal black bullet lube.

1-16 has a Brinell hardness of about eleven which is close to what I get with my batch of crimp on wheelweights. I still use a soft and sticky lube that requires no heater.

But the question was not what did Keith do, but about the rounds vs. flat bottom grease groove and is their any clear evidence on if better than another. I don't think that has been answered.

I have fired many Keith bullets including 358429. 452423, 454424 and 429421 of the original design coming from old unvented mold bocks as well as 358429, 452423 and 429421 late 60's vintage round groove molds. I have fired them from 1-16 and ACWW and lubed them with a variety of soft lubes including black sticky Lyman/Ideal of which I still have a goodly supply. This is pretty much an apples and apples comparison real Keith bullets, alloy and lube.

The bottom line is I have yet to detect any real, repeatable differences in lube groove design based on my shooting over 50 years with these bullets.

For the record: I cast my first Keith bullet (452423) in 1959, read everything Keith wrote, corresponded with him and even had the pleasure of spending a couple hours with him, Bill Jordon and a couple of others around a table drinking whisky and telling gun stories.

I don't think all of us are as ignorant, inexperienced and generally in the dark on the subject at hand, as some would make it seem.

Keith used 16:1 lead/tin....... he considered it a hard alloy and a stable one with no age hardening ingredients except for trace amounts.

That Lyman lube has a history.... do you know it and it's the lube's proper name? Lyman sure didn't come up with it, but it sure is darned good stuff.

Please Charles, spending a little time with Keith and other worthies does not make you equal to them........ and you aren't Elmer either. He knew what to do with a handgun (short and long range) and was ostracized for it for many years when others considered what he said and wrote as fabrication.

[Char-Gar]

Keith used 16:1 lead/tin....... he considered it a hard alloy and a stable one with no age hardening ingredients except for trace amounts.

That Lyman lube has a history.... do you know it and it's the lube's proper name? Lyman sure didn't come up with it, but it sure is darned good stuff.

Please Charles, spending a little time with Keith and other worthies does not make you equal to them........ and you aren't Elmer either. He knew what to do with a handgun (short and long range) and was ostracized for it for many years when others considered what he said and wrote as fabrication.

You still have not told me anything I don't know and in fact agree with. You still have not talked about the subject of this thread, i.e. round vs. flat bottom lube grooves on Keith style bullets. I am still waiting for this deep knowledge on that subject that none of the rest of us has.

[45 2.1]

The question, which is being dodged, is round bottom vs. flat bottom lube grooves on Keith style bullets.

Elmer wrote about such things. I proved it to myself out of a scoped Rem. M788 rifle in 44 Mag at 200 yards some 30+ odd years ago. I have no need to prove it to you or anybody else here, but the round lube grooves shot MOA for 5 shot groups and the altered flat bottom ones shot 5/8 to 3/4 MOA for 5 shot groups on the same day in the same hour and conditions... one group after the other alternating types with the same barrel condition. A 70's era Lyman 429421 round lube groove boolit to Elmer's specs.



I am still looking for a body of knowledge to back up claims of undefined para-normal shooting feats. It is impossible to evaluate such claims, so they must be disregarded. Anecdotal accounts of who did what, fails to impress me or just about anybody else around here that has been painted as "unknowing". I am also unimpressed with cell phone pics of targets.

Elmer was vindicated near the end of his life, many years after he told others what he did and what he used. Maybe you need to find out what was used and how it was used and try it yourself. The how is most of the problem with trying to duplicate things along with ability.


When somebody turns in this kind of performance in a registered Cast Bullet Association match with ten shot groups, witnesses and scores, I will pay attention, very close attention. In other words, I will believe it when it is printed in The Fouling Shot.

So, nothing on this forum is worth much but what comes out of the south end of a north bound male bovine...... So You Say and Allude to.

[45 2.1]

You still have not talked about the subject of this thread, i.e. round vs. flat bottom lube grooves on Keith style bullets. I am still waiting for this deep knowledge on that subject that none of the rest of us has.

I suspect several people here know exactly what I do about Elmer's boolits (it's no secret if you have the determination to duplicate it), but they have no wish to talk with some of the people here who don't believe and just want to palaver OR those that have no idea what to do to prove what was said.

[Char-Gar]

Here we have a thread that has lots of opinions and little knowledge posted...... just like most of the others threads about the same thing in the past. Very very few folks take the time to find out what really does happen or why certain things were done in the past.

OK..Now we know your empirical evidence that allows you to have such lofty opinions as above. 30 years ago, you shot some groups from a 44 Magnum rifle and the issue is settled for all times.

This is sorta what I expected, but had to drag it out of you.

[45 2.1]

OK..Now we know your empirical evidence that allows you to have such lofty opinions as above. 30 years ago, you shot some groups from a 44 Magnum rifle and the issue is settled for all times.

This is sorta what I expected, but had to drag it out of you.

Your words..... you do know what assumptions make you. What part of "I proved it to myself" do you not understand?

[Char-Gar]

Bobby, I will take leave of this exchange and replace you on ignore. I think folks reading this exchange can figure this stuff out with what they have before them.

[45 2.1]

Bobby, I will take leave of this exchange and replace you on ignore. I think folks reading this exchange can figure this stuff out with what they have before them.

Please do so and remain so........... I have no wish to banter with you when you could have asked a direct question and didn't. You said "The question, which is being dodged, is round bottom vs. flat bottom lube grooves on Keith style bullets"....... and left out pros and cons with no question asked, just an incomplete sentence. In the first post he asked for " some feedback", not proof as you have made it out.

You also did not answer my last direct question..... and folks reading this exchange can figure that out also.

[DrCaveman]

Thanks for the background provided and bits of experience. That is about all I can ask for, since I know this is a 'debate' with no true consensus to be arrived at.

I didn't expect things to heat up this much, but hey it's probably better to happen here than in a saloon where fists may fly and then people lose their freedom.

It seems like I will be looking more toward flat-bottom groove styles, but that it shouldn't be a more decisive factor than chamber, throat, and barrel fit.

It seems like pan lubing would work better with a square/flat groove due to a sharper cutting of the lube as the boolit is removed. Although my 358429 with rounded groove pan lubes quite well.

Bore alignment as mentioned somewhere in the thread seems like it would be better with a sharp driving band corner. Further, a more square groove will allow more lube capacity per length of boolit consumed, thereby allowing more length for driving bands for a given boolit weight and length.

Does the previous paragraph seem like a good summary of what has been said? Am I getting it?

[Oreo]

a more square groove will allow more lube capacity per length of boolit consumed, thereby allowing more length for driving bands for a given boolit weight and length.

Close. Groove depth needs to be considered as well, and the lost lube capacity effect is less pronounced the more obtuse the draft angle gets.

[frank505]

The rifle black powder designs have flat bottom grease grooves do they not? Recover some bullets and put a micrometer to them. Lots to learn if you quit the pissing match.

[DrCaveman]

The rifle black powder designs have flat bottom grease grooves do they not? Recover some bullets and put a micrometer to them. Lots to learn if you quit the pissing match.

Frank

Is the micrometer measuring the final diameter of the lube groove, looking for growth via compression or centrifugal force or something? Not sure what the recovery of the boolits is telling us here, but im all ears.

Pretend there is no pissing match, and please carry on with discussion of flat-bottom lube groove boolits vs round lube groove boolits. Im hoping that a few more cold-hard facts regarding performance will show themselves.

While everyone will still have their personal preference and attitude, a succinct list of pros and cons will allow me (and others) to make an informed decision based on our needs or wants

[DrCaveman]

Close. Groove depth needs to be considered as well, and the lost lube capacity effect is less pronounced the more obtuse the draft angle gets.

Got it. My concern was not to maximize lube capacity, but rather to maximize driving band length for a given boolit length and weight. Based on what you are saying, a nearly-right-angled draft angle (say 7 degrees obtuse) which led to a lube groove of say 65% driving band diameter (pretty deep, yes?) could allow one to get away with a pretty short lube groove. Right?

Im guessing there is a threshold of drive band diameter ratio to lube groove diameter above which the boolit gets very difficult to drop from mold. Am i wrong?

So i hope this discussion may add a new element: in the interest of maximizing driving band length, and given the high-quality lubes we have at our disposal these days, how deep of a flat-bottomed lube groove can one get away with while still being able to cast boolits at a reasonable rate?

[leadman]

Take a look at the Lee truncated cone in 40 S&W and 9mm. These have very shallow flat bottomed lube grooves that hold enough to get the boolit out the end of the barrel without leading the bore. Not sure a really deep LG is needed as it certainly can be a pain to cast with.
You could coat your boolits with the HI-Tek bullet coating so you do not need to worry about wax type lube. I tested some 30-06 last week at 1950 fps and no leading at all. My 41 mag boolits had up to 1,340 fps with no leading and excellent accuracy. I do plan further tests.

Maybe it is time to move beyond the conventional wax type lubes?

[Three-Fifty-Seven]

http://i153.photobucket.com/albums/s220/ShawnVT/Guns/359640RoundHPinWater3.jpg (http://s153.photobucket.com/user/ShawnVT/media/Guns/359640RoundHPinWater3.jpg.html)

[turbo1889]

If you really want to recover boolits with nearly no damage from being stopped and all the deformation on them being from the trip down the bore. Fire them into a snow drift. Not a big ice berm piled up by a plow, a natural blown snow, powdery snow drift and then recover them. That is the best medium I have ever found to stop a boolit, even one fired from a high powered rifle at high velocity without damaging the boolit in any detectable way. Be prepared to shovel and sift through a lot of snow and have a big snow drift to shoot into. Penetration to stopping depth is measured in feet or even yards.

[Oreo]

Got it. My concern was not to maximize lube capacity, but rather to maximize driving band length for a given boolit length and weight. Based on what you are saying, a nearly-right-angled draft angle (say 7 degrees obtuse) which led to a lube groove of say 65% driving band diameter (pretty deep, yes?) could allow one to get away with a pretty short lube groove. Right?


I was speaking only about the mater of geometry. In that sense, yes you can make a deep narrow lube groove with the same volume as a shallow wider groove. That says nothing about performance of either the mold or the boolit.

I found in my research that a lube groove need only be a little deeper then the rifling on the barrel, however going too much deeper then that can cause problems. I don't pretend to have a deep understanding of what those problems might be or what else contributes.

Don't get obsessed with splitting hairs over minutia. You're asking good questions but its easy to look at a blueprint at 10,000x scale and get hung up over .005" this way or that. When you bust out the calipers and compare to a bullet held in hand it becomes clear that. 005" of boolit length, driving band or lube groove in any dimension by itself won't make or break a design.

[DrCaveman]

123dieselbenz

that is something. Where did the metal go? Those lube grooves are a good 50% of their original length, and dont look particularly fatter. Now, I wonder whether there is any negative or positive to this shrinkage or merely academic study. Then, I wonder if the round-lube-groove designs show the same sort of compression/shrinkage.

I could see some degree of compression adding to obturation of boolit in bore. If the compressive strength of the alloy exceeds the compressive pressure of the load, perhaps a "weak" outlet for metal displacement such as a thin-shanked lube groove is useful. Maybe stretching here...but it seems that a momentary shift in boolit shape as the lube groove compresses could allow the pressure to reach optimal levels before boolit discharge.

Another way of saying this would be that the structural weakness of the lube groove shank allows the alloy strength to be the dominant force in determining boolit deformation during the initial portion of launch. As opposed to boolit construction (other than the intentially weak lube groove shank).

I dont know, still probably splitting hairs over minutia but the pics posted show something interesting I had not noticed or considered possible before. Hard for that not to inspire some thinking outside the box.

[btroj]

Where did the metal to? look at the nose shape of the fired vs unfixed bullets. The bullet changed shape entirely upon firing. Look at the nose, see how far up the nose the rifling engaged? Look at the unfired example, that portion of the nose is small enough in diameter that it shouldn't engaged the rifling at all, yet it did. All this because of bullet obturation. Make that bullet a lot harder and the rifling doesn't engage the bullet nose near as much at the same pressure.

[Three-Fifty-Seven]

http://i153.photobucket.com/albums/s220/ShawnVT/Guns/AM378275HRubber.jpg (http://s153.photobucket.com/user/ShawnVT/media/Guns/AM378275HRubber.jpg.html)

[Char-Gar]

Years back, Paul Matthews, a cast bullet maven, designed a bullet with long but shallow lube grooves, thinking this might be better than longer and deeper grooves. The amount of lube stayed the same, just the geometry of the groove where it was contained. He wrote up his results in Gun Digest.

I have been many years but my memory tells me the results were the long shallow grooves performed not as well as the traditional deeper but narrower grooves. This gives credence to the notion that a bullet collapses to pump out the lube. The shallower grooves gave a thicker and stronger bullet that did not collapse to pump out the lube.

Like I said, it has been many years back, but that is my memory on the subject.

[Oreo]

What's interesting to me about this compression pumping theory is what's to stop the alloy from flowing unevenly? Why don't we (or do we?) see boolits recovered with un-square bases? If it happened it certainly must be awful for accuracy.

[45 2.1]

What's interesting to me about this compression pumping theory is what's to stop the alloy from flowing unevenly? Why don't we (or do we?) see boolits recovered with un-square bases? If it happened it certainly must be awful for accuracy.

If your interested in the un square bases concept, use a recovery box for an undamaged boolit to look at. The easy way to test this is long range groups...................

[Cap'n Morgan]

If you really want to recover boolits with nearly no damage from being stopped and all the deformation on them being from the trip down the bore. Fire them into a snow drift. Not a big ice berm piled up by a plow, a natural blown snow, powdery snow drift and then recover them. That is the best medium I have ever found to stop a boolit, even one fired from a high powered rifle at high velocity without damaging the boolit in any detectable way. Be prepared to shovel and sift through a lot of snow and have a big snow drift to shoot into. Penetration to stopping depth is measured in feet or even yards.

F. W. Mann found, almost by accident, that sawdust, mixed with oil, would stop a bullet without any visible damage. If dry sawdust was used the bullets would flatten on impact, and while wet sawdust would lessen the damage, for optimum results the sawdust must be saturated with light machine oil. The bullet would often penetrate as much as four or five feet before stopping, so it would take quite a large amount of sawdust and oil to replicate this. Still, it should be easier than finding a snowdrift in July...;-)

[Char-Gar]

What's interesting to me about this compression pumping theory is what's to stop the alloy from flowing unevenly? Why don't we (or do we?) see boolits recovered with un-square bases? If it happened it certainly must be awful for accuracy.

I really don't know if the pumping thingie is real or not. It may or may not be. But what I do know is the base of a bullet had better be flat, square and parallel to the muzzle at it exits or the escaping gas will push unevenly on the base as it exits the muzzle and that is not good for accuracy.

I also know that bullet compression inside the barrel will vary with alloy, burning rate of powder and total amount of pressure. To much compression and accuracy goes south. That is the reason why fast powders like 2400 begin to loose their usefulness after about 1.8K fps and slower powders do better. A bullet that is shoved down the barrel suffers less compression than one beated down the barrel with fast powders.

[Alan in Vermont]

........... less than 1.25 MOA at 385 yards at about 2400 fps for group cores

What I want to know is WTH is a "group core"? Do you get to pick what constitutes the "core"?

[Char-Gar]

What I want to know is WTH is a "group core"? Do you get to pick what constitutes the "core"?

I would guess a fellow would just measure the bullet holes bunched up and disregard those outside this core, but that is just a guess. If I am correct, this kind of scoring in not allowed in any form of competitive shooting I know of. We all have fliers and shots called out, but those count in score and group size. Like you I await the answer.

[Alan in Vermont]

WOW!, once again I have learned something from this group. I can now shoot tiny groups with the best of them, just claim the hits I want and disregard the others. That's a good way to get sub-MOA groups out of some old clunker that is hard pressed to shoot minute-of garbage-can.

I have to admit to disregarding shots I call "out" when I'm working on loads. But, if I didn't call it as a bad shot it stays in my results. I just can't see lying to myself to try to impress anyone.

Now if I could just find that can of "Internet BS Repellant" that I know I have around here somewhere,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

[Alan in Vermont]

If your interested in the un square bases concept, use a recovery box for an undamaged boolit to look at. The easy way to test this is long range groups...................

Doing that, would you judge that the ones with out of square bases would be the ones outside your "core" and be irrevelant?

[Jailer]

Turbo1889,

Care to share what you found from shooting into snow? We don't get much down our way! ;)


Well I'm not Turbo1889 but I'll share. He's right, it is the best to recover fired bullets with no impact damage.

These were shot from a Glock 21. You'll notice on the TL boolits 2 distinct things. Evidence of skid and gas cutting at the base. This was a few I fired in the winter while I was first casting and figuring things out.

http://i19.photobucket.com/albums/b180/Jailer/posting%20pics/230TC453.jpg (http://s19.photobucket.com/user/Jailer/media/posting%20pics/230TC453.jpg.html)
http://i19.photobucket.com/albums/b180/Jailer/posting%20pics/recoveredGlockboolits5.jpg (http://s19.photobucket.com/user/Jailer/media/posting%20pics/recoveredGlockboolits5.jpg.html)

[DrCaveman]

Jailer

Those are interesting. Without unfired boolits to compare, im not totally sure, BUT, it appears that the lube groove in your TC boolits is about the same length as it was when cast. So, at 45 acp pressure, i guess the compression/deformation isnt happening.

On the other side of the coin, it seems that extreme deformation is happening with the tumble lube design. Was there a big accuracy difference?

Is that residual LLA on the nose of the TL SWC? If so, i guess lee's claims about its durability are validated.

That is the best photographic documentation of polygonal rifling impressions that i have seen. I trust there was no significant leading?

[45 2.1]

Doing that, would you judge that the ones with out of square bases would be the ones outside your "core" and be irrevelant?

Ya know, I just love the sniper mentality here. If you don't like something, just assassinate it or them by saying cute witticisms. We have quite a few people on this forum that do that regularly. If you really don't understand what is talked about a nice direct question without the gas would do. You need to talk to some of the long range black powder cartridge shooters. Ask them what happens to their shot when a strong gust of wind coincides at the instant the trigger is pulled, especially when they are testing loads and rifles....they will know and most would be able to tell you about where it should be on the target. Most folks here don't shoot far enough away to know what wind does to lead and they certainly can't shoot long range lead HV and have a small set of holes with one out due to windage.

[swheeler]

What I want to know is WTH is a "group core"? Do you get to pick what constitutes the "core"?

I believe this is the kind of group scoring used by an x-member here for his famous 6.5 Swede at high velocity. When you just pick those shots that hit closest to each other you never see the effects of rpm's, therefore it doesn't exist and all your groups are sub moa;);) it's core alright, rotten to the core.

[Char-Gar]

Long range shooting is a very flexible term. What is long range for some is not for others. I cut my teeth shooting 4 position high power in local, state and national competition. Ranges out to 600 yards were the norm. I did some 1,000 yard shooting as well, but not as regular fare. This was done with 03 Springfields and later National Match Garands. This is just to say, that I for one have a reasonable understanding of what is involved in shooting at longer ranges. I am certain that are others here, whose knowledge and experience far exceeds mine.

I do know that we were not allowed to shoot "core groups" and to disregard shots outside of the central cluster. Every shot counted then and still does now. This does not change.

How a fellow wants to evaluate and measure his own personal groups is his business...until...he comes to places like this and claims to be able to do something others have been unable to do. The next step is to claim superior knowledge and wisdom, without full disclosure of how his stats are arrived. If we all used the same methods of measurements, then perhaps he would have something to offer. If I only reported "core groups", then I also would appear to have superior knowledge and shooting skills. But to do so would be to misrepresent my knowledge and abilities.

Another thing that never changes is the odor of BS. It is very recognizable to the nose and to the eye when it appears in print. Perhaps folks should just allow it to pass and not call a foul on it, but perhaps not. There is continual influx of new shooters and new people on this and other boards and they should be able to depend on straight information to help them along the way. Nonsense and ridiculous claims all to often create false expectations and send them down the wrong path. This is not good or helpful to anyone.

Therefore my motivation for threads such as this, is not who knows more and who knows less, but maintaining a reasonable standard of honesty and reliability so that others may progress in their casting, shooting and loading. This does not make me popular with some folks, but that is just the price I will have to pay. Nobody unhappy with me is signing my paycheck

[swheeler]

A person has to learn to seperate the oats from the chaff on these forums, and yes, recycled oats does have a certain smell to it.

[Southron]

If you ever recover any of the cast bullets you have fired, you will note that there is still a lot of lube left in the grease grooves of your fired bullets. Apparently, it takes very little lube to adequately lubricate a bullet as it flies down the bore of your rifle or pistol.

Square VS Rounded grease grooves? I have never been able to tell a difference between the way they cast and shoot, so the actual shape of the grease groove is most likely a moot point.

I met Elmer Keith back in the mid-1970's and he was truly a "Larger Than Life" character. I think he was suffering from some type of age related dementia when I met him because his short conversation with me was rather confused. I was very nice and respectful to him. The man accomplished a lot in his life and I realize that sooner or later, if we are lucky, we all get old.

[Char-Gar]

If you ever recover any of the cast bullets you have fired, you will note that there is still a lot of lube left in the grease grooves of your fired bullets. Apparently, it takes very little lube to adequately lubricate a bullet as it flies down the bore of your rifle or pistol.

Square VS Rounded grease grooves? I have never been able to tell a difference between the way they cast and shoot, so the actual shape of the grease groove is most likely a moot point.

A good discussion, with no agreement can be had about just what cast bullet lubricant does. Many will posit that "lubricant" is a misnomer and it has little to do with lubricating the bullets path down the barrel, but forms a seal at the base of the bullet to keep the fire off of the sides of the bullet. The actual lubrication of the bore being very much a secondary function.

To be truthful, I really don't know what it does. I know what works and does not work, but I don't know why. I doubt if most of those who feel they know truly do, but rather advance theories and repeat what others have said. It must do something because it is needed in most instances. Note, I said most and not all.

I think I will go over to Cast Bullet Association board and ask Ed Harris what is the purpose of bullet lube. His is an opinion I would take pretty much as gospel.

I met Elmer Keith back in the mid-1970's and he was truly a "Larger Than Life" character. I think he was suffering from some type of age related dementia when I met him because his short conversation with me was rather confused. I was very nice and respectful to him. The man accomplished a lot in his life and I realize that sooner or later, if we are lucky, we all get old.

Like most people who suffer strokes, Keith had several smaller ones before he had the big one that pulled the pins out from under him and put him in a nursing home where he was until he died. I met him back in the mid-60s when he was still hitting on all eight cylinders.

[Jailer]

Jailer

Those are interesting. Without unfired boolits to compare, im not totally sure, BUT, it appears that the lube groove in your TC boolits is about the same length as it was when cast. So, at 45 acp pressure, i guess the compression/deformation isnt happening.

On the other side of the coin, it seems that extreme deformation is happening with the tumble lube design. Was there a big accuracy difference?

Is that residual LLA on the nose of the TL SWC? If so, i guess lee's claims about its durability are validated.

That is the best photographic documentation of polygonal rifling impressions that i have seen. I trust there was no significant leading?

There was leading with both of those designs because they were sized too small. And yes that is LLA left over on the nose and in the grooves in the SWC. The TC boolit is not deformed in any way. If it weren't for the rifling marks you swear it could be lubed and shot again.

[Alan in Vermont]

You need to talk to some of the long range black powder cartridge shooters. Ask them what happens to their shot when a strong gust of wind coincides at the instant the trigger is pulled, especially when they are testing loads and rifles....they will know and most would be able to tell you about where it should be on the target. Most folks here don't shoot far enough away to know what wind does to lead and they certainly can't shoot long range lead HV and have a small set of holes with one out due to windage.

I do know what happens when you get caught by the wind, it ends up a 9 or an 8, or it blows a really sweet group. I also know people who claim fantastic results, to the point of being beyond the laws of probability. A MOA rifle may be able to cut a one hole group, if you shoot it enough, but it's about impossible to shoot them on demand.

You never did explain your "core group". What is the criteria that makes a shot outside the core? How much of that determination is based on how badly you need an impressive number? There's a lot left to the ethics of the shooter when you start a process that allows picking and choosing which shots count.

Lacking any firm criteria I have to think that some of your claims are not so amazing when one considers the amount of smoke(screen) you have to overcome.

[45 2.1]

I do know what happens when you get caught by the wind, it ends up a 9 or an 8, or it blows a really sweet group. OK Alan, since you asked in a decent form, I'll explain it to you. In your first sentence you say "it blows a really sweet group".... that really sweet group would be a core group, one that would be a group if you hadn't had one out. I also know people who claim fantastic results, to the point of being beyond the laws of probability. The CBA record groups have less than 0.2 MOA possible, just how is what I said beyond the laws of probability? A MOA rifle may be able to cut a one hole group, if you shoot it enough, but it's about impossible to shoot them on demand. I never said it was a MOA rifle, just a production Rem. 700. Jacketed match reloads have shot quite a bit under MOA in it. We have people here that can probably do much better than you state... on demand.

You never did explain your "core group". That really sweet group with a errant wind caused flyer.... as you noted above by you. What is the criteria that makes a shot outside the core? Usually a horizontal deflection due to wind, but if shot far enough away there are other documented problems also. How much of that determination is based on how badly you need an impressive number? There were two of us shooting. The rifles owner had two wind driven flyers.... I didn't. There's a lot left to the ethics of the shooter when you start a process that allows picking and choosing which shots count. We were not shooting a match nor competing... anywhere. I was introducing a loading technique for my friend to learn. I explained why he had flyers. It's that simple. The problem is some folks here get their shorts in a bind when I start talking about HV long range riflery that they can't do and find impossible.

Lacking any firm criteria I have to think that some of your claims are not so amazing when one considers the amount of smoke(screen) you have to overcome.

[badgeredd]

A person has to learn to seperate the oats from the chaff on these forums, and yes, recycled oats does have a certain smell to it.

:D :lol: [smilie=1:

Well put Scott. MEASURED velocities and true groups are the only accepted criteria to most shooters looking for perfection.

I haven't found any great difference in boolits of the same design but differing lube groove shapes. I know from a machinists perspective roughly square/rectangular/trapezoidal lube grooves are easier to cut or make cutters for. My experience, limited as it might be, seems to point out that our newer modern lubes are superior to some of the old lubes and require less volume of lube to be effective.

Edd

[Char-Gar]

I did indeed go to the CBA site and asked the purpose of bullet lubricant and here is my question followed by two answers which in my estimation are very credible.

First my question:

"Guys, does anybody here know, really know the purpose of cast bullet lubricant. Is the purpose of lubricate the passage of the bullet down the barrel or form a seal/gasket at the base to keep the fire off the sides of the bullet base? Perhaps there is another alternative or some kind of combination.

I have been reading opinions and theories for years, but it seems like this would be a known and proven fact after the passage of this many years. Is there a conclusion or just a variety of opinions? I would really like to know."

Please guys, don't state you opinion as if it were a fact. I don't need any more of that. I am seeking knowledge and not more opinions, theories and speculation. I really do want to know.

Next and answer from Ed Harris:

"Ken Mollohan nailed this years ago. Our bullets lubes form an ablative coating which coats the bore to prevent adhesionof "vaporous lead" abraded from the surface of the bullet, by action of powder gases. This is described as the "boundary layer" principle of lubrication, and in my experience is correct."

Last an additional response from John Alexander CBA President;

"Ed is right that the only person that I know of that has looked into this question in depth with a series of well designed experiments to back up his theory is Ken Mollohan.

Ken reported his work in the Fouling Shot quite a while ago and more recently referred to it. I am sorry that I don't know the location of those articles.

I can sympathize with Charger's lack of interest in hearing more opinions and unsupported theories. We have lots of then about cast bullets and a shortage of the kind of actual controlled experimentation that Ken Mollohan did."

[felix]

Perfect answer. ... felix

Accuracy is maintained when the boundary is maintained, giving a consistent shot-to-shot boolit acceleration curve. ... felix

[Char-Gar]

Perfect answer. ... felix

Accuracy is maintained when the boundary is maintained, giving a consistent shot-to-shot boolit acceleration curve. ... felix

Thanks Felix, you are a serious science guy and understand that stuff. While I have a good education (fine arts, law and theology), I am science deficient. I had to go an look that stuff, up but I think I have a good grasp on it now.

Until somebody comes up with a better answer, backed up with better science, I take this as the last word on the subject. I have grown very weary of opinions offered up as fact and it is good to have some facts based on experimentation. I am sad to say, that Ken passed away a few months back and we are without his vast body of knowledge any more. But he did leave much behind in his writings.

[DrCaveman]

Ok guys, this wisdom from harris/mollohan is much appreciated and seems to be more definitive than most statements on the subject.

What does this say about lube groove shape? It seems as though a consistent rate of delivery of lube to the bore is tantamount to maintaining the boundary...that is, unless the lube burns or boils off. So, the question is: which shape of lube groove will provide more uniform lube dispersion?

Since the dispersion of lube into the bore is related to the boolit spinning while hot gases are bringing the lube to liquid state, it makes sense that the process is more radial than linear. Therefore it makes sense that a radial (rounded) lube groove would fit into this paradigm somehow.

Remember, while lube function is part of the discussion, i was asking about mold design, so lets try to tie back to lube groove shape. Maybe the CBA guys have insight about that, too. Itd be nice to track down and republish those mollohan articles. Bet a bunch of threads on the forum would be assisted

[Oreo]

I haven't seen a link to this guy Mollohan's work yet so forgive me that I haven't read it before posting this.

That we know more about what the lube does and how is imo entirely separate from what the groove does and how. Whatever Mollohan had to say about lube doesn't change the real-world practical aspect of what works and what doesn't. What we as a group know from experience is that good results can be had from a wide range of groove profiles. We know that trying to scientifically calculate a precisely optimal groove profile for a specific application is a canyon of permutations as wide as it is deep. Imo, trial and error starting with the most likely candidates based on prior experience is likely to be the quickest path to success.

In a nut-shell: the only way to really know is to try and see and even then, someone else is likely to get different results.

[badgeredd]

I haven't seen a link to this guy Mollohan's work yet so forgive me that I haven't read it before posting this.

Whatever Mollohan had to say about lube doesn't change the real-world practical aspect of what works and what doesn't. What we as a group know from experience is that good results can be had from a wide range of groove profiles.

In a nut-shell: the only way to really know is to try and see and even then, someone else is likely to get different results.

Mollohan is/was our own Molly. His observations have been based on real world applications. For that reason, anything I find written by him has my attention. We are poorer for his passing to the shooting fields beyond.

Edd

[Char-Gar]

Gentlemen. The Fouling Shot is the journal/magazine published by the Cast Bullet Association and a source of very good information that pre-dates the internet and places such as this. Back issues are available either on disc or paper and Molly's work, as well as that of Ed Harris and others are there to be read.

The CBA also puts on regular matches in several different classes with cast bullets. This is the practical application of cast bullet shooting. The shooter who shoots the smallest group, in a given class, at a given range wins. This is not theory, or opinion, it is holes in paper.

The CBA also has Postal Matches for those unable to travel to the matches. Putting your rifle, your load and your skills up against another's can be intimidating, but it does weed out the blow hards and posers.

Match results are published in The Fouling Shot, and this includes the rifle, bullet, alloy, sizing diameter, powder, powder charge and bullet lubricant. Time spent analyzing this information will yield a huge benefit in cast bullet learning, for this is not Internet gas, but real holes in real paper. A membership in the Cast Bullet Association that includes a subscription to The Fouling Shot is a very good expenditure of a few bucks each year for those interested in cast bullet shooting.

I suppose one could do a study of the bullets used to win these matches and gain some information about lube grooves, their size, configuration, depths and so forth. However, I truly doubt if that is worth the time to do. It is my opinion, that other factors are far more important that flat bottom vs. round bottom lube grooves. To expend time on that would be "majoring on the minor". However some of us have an inquisitive nature and that just might be an itch that somebody needs to scratch. It is just something that does not interest me. It have enough problem putting what I do know into practice to concern myself with what I don't know, but that is just me.

Shooting competition (small bore, high power, bench rest, skeet, Bullseye Pistol and handgun falling plates has been a part of my life for a half century. It keep me involved and honest. I have never been the champion at anything, but that is not what it is all about. It is about discipline, riflecraft, accountability and the fellowship of shooters.

In this day of the Internet, we have become a group of posters and in the process much of has been lost. Some kind of organized competitive shooting even, keeps our skills honed and we have great fellowship with like minded people. There are always a few tightly wound folks to whom winning is everything, but 95% are just there to have fun and hang out with others shooters at the range. I compete on a weekly basis and would find life and shooting much less rewarding without that.

[Oreo]

Mollohan is/was our own Molly. His observations have been based on real world applications. For that reason, anything I find written by him has my attention. We are poorer for his passing to the shooting fields beyond.

Edd
I mean the man no disrespect and if you guys say he pioneered an area of knowledge then I believe it. I don't see how that diminishes what I posted, but maybe it would be more clear to me if I read his work. As the scope of his work has been presented here, I stand by my own words.

Did the man have a lube groove preference of his own? Keith is the only name that ever comes up about lube grooves. If Mollohan had similar or differing thoughts that would be welcome info.

[Char-Gar]

I mean the man no disrespect and if you guys say he pioneered an area of knowledge then I believe it. I don't see how that diminishes what I posted, but maybe it would be more clear to me if I read his work. As the scope of his work has been presented here, I stand by my own words.

Did the man have a lube groove preference of his own? Keith is the only name that ever comes up about lube grooves. If Mollohan had similar or differing thoughts that would be welcome info.

I don't think anybody took what you said as disrespectful, nor diminished your post. I don't have any answers to your questions and I try and keep my mouth shut when faced with my own ignorance.