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Thread: Square lube groove vs rounded - pros and cons

  1. #1
    Boolit Master DrCaveman's Avatar
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    Square lube groove vs rounded - pros and cons

    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

  2. #2
    Boolit Master

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    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 !
    GP100man

  3. #3
    Boolit Grand Master Char-Gar's Avatar
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    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.
    Disclaimer: The above is not holy writ. It is just my opinion based on my experience and knowledge. Your mileage may vary.

  4. #4
    Boolit Master DrCaveman's Avatar
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    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

  5. #5
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    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?

  6. #6
    Boolit Grand Master

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    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
    If it was easy, anybody could do it.

  7. #7
    Boolit Master turbo1889's Avatar
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    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.
    Last edited by turbo1889; 05-20-2013 at 01:26 AM.

  8. #8
    Boolit Grand Master Char-Gar's Avatar
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    Quote Originally Posted by DrCaveman View Post
    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.
    Disclaimer: The above is not holy writ. It is just my opinion based on my experience and knowledge. Your mileage may vary.

  9. #9
    Boolit Master
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    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+.
    It's all chicken, even the beak!

  10. #10
    Boolit Master

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    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

  11. #11
    Boolit Master
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    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.

  12. #12
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    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.
    Last edited by Oreo; 05-20-2013 at 11:49 AM.

  13. #13
    Boolit Grand Master

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    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.

  14. #14
    Boolit Master
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    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.

  15. #15
    Banned 45 2.1's Avatar
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    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.

  16. #16
    Boolit Master turbo1889's Avatar
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    Quote Originally Posted by Oreo View Post
    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.

    Quote Originally Posted by 45 2.1 View Post
    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.

  17. #17
    Boolit Grand Master Char-Gar's Avatar
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    Quote Originally Posted by 45 2.1 View Post
    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.
    Disclaimer: The above is not holy writ. It is just my opinion based on my experience and knowledge. Your mileage may vary.

  18. #18
    Banned 45 2.1's Avatar
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    Quote Originally Posted by turbo1889 View Post
    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.

  19. #19
    Boolit Grand Master Char-Gar's Avatar
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    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.
    Last edited by Char-Gar; 05-20-2013 at 03:19 PM.
    Disclaimer: The above is not holy writ. It is just my opinion based on my experience and knowledge. Your mileage may vary.

  20. #20
    Banned 45 2.1's Avatar
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    Quote Originally Posted by Char-Gar View Post
    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.

    Quote Originally Posted by Char-Gar View Post
    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.

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BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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