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Thread: single lube groove or two smaller ones?

  1. #1
    Boolit Master Oklahoma Rebel's Avatar
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    single lube groove or two smaller ones?

    http://www.accuratemolds.com/img/bul...37-280TB-D.png does a boolit design such as this usually work better (accuracy, cleanliness) with one big .2 deep lube groove, or two smaller ones half the width but same depth? would take a little musical chairs but I could change it to two if I get enough sensible answers saying to change it, or if its better to leave well enough alone. thanks!-Travis
    Last edited by Oklahoma Rebel; 11-02-2017 at 10:30 AM. Reason: spelin' wus rong!
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  2. #2
    Boolit Master


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    Depends on if you listen to Elmer or not.

    Elmer Keith was a proponent of a single, large lube groove. Of course, lube technology has changed a bit in the intervening decades.

  3. #3
    Boolit Master


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    I still like a Keith style bullet.

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    I'd say use that boolit mold just the way it is. Looks great to me.
    You actually end up with part of a lube groove just in front of the gas check.

  5. #5
    Boolit Master


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    I like the meplat.

  6. #6
    Boolit Master Oklahoma Rebel's Avatar
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    cool, and thanks for the compliment lar45,coming from you that means a lot! I designed it myself! my dad put in on autocad for me, even though tom didn't need that, just a detailed drawing. I may have to make minor tweaks to it when I get my gun. every time I am soo close to getting it, something else comes up! I guess that's what being grown up is all about. life really isn't fair, they said it, but I never listened! lol
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  7. #7
    Boolit Master quail4jake's Avatar
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    Now evaluate the theory and success of Loverin style boolits, I am!

  8. #8
    Boolit Master Oklahoma Rebel's Avatar
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    to be honest, I know they are the multi-groove tapered designed boolits, but that's about it...they gradually get smaller from base to nose, right?
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  9. #9
    Boolit Master Oklahoma Rebel's Avatar
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    do you guys think the loaded OAL of this boolit/cartridge, crimped in the crimp groove, of 3.181 leaves enough room for loading considering the saami length is set at 3.291? I am just a bit concerned that the meplat may cause feeding issues, so I made sure to give it a bit of extra room. I know you can only give a halfway answer because all guns are different, this one being a CZ550FS 9.3X62.
    An armed man in a citizen.
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  10. #10
    Boolit Master quail4jake's Avatar
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    That's right, Rebel and you and I will partner in answering your question. I just ordered a 6,5 mould from NOE in a Loverin style, this is my first so I'll tell you how we do! Some of the theory behind the multi narrow driving band boolits is the upset of the entire length on acceleration to apply hydrostatic force to all those lube grooves and slick the boolit down the bore, then there's the theory of gradual engraving of the incrementally larger driving bands and filling the throat with a tapered, self centering boolit! I clearly need more education in this corner of interior ballistics (as well as a lot of other things!).
    OK, then there's the Elmer Kieth philosophy that says "don't over think it" or "Hell, I was there!". Mr Kieth is a man I truly admire and his boolit designs are unquestionably successful, with wide driving bands and one big groove for a couple pints of soft alox loob, made of squishy 16:1 alloy. How did he ever become so successful without IT? BALLS! just good old fashioned try it and see BALLS! One of my favorites,
    Truthfully, I think in the end we will find that narrow or wide driving bands have specific applications in which each works best. Now to find the sweet spot!

  11. #11
    Boolit Master Oklahoma Rebel's Avatar
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    well good luck with your 6.5, I think the idea of having a boolit that starts narrow and gets wider towards the base does make sense, as far as helping to start and keep the boolit centered, especially when going from throat to rifling. as far as having the multiple grooves, I can see why having more grooves over more length of the boolit would seem to be better, but I think that a single deep groove makes a nice floating reservoir of lube, with gas pushing some out in front of the groove (lets face it, we cant seal out all those gas molecules!) while leaving behind a nice slick surface for the next boolit in line. i'll go check out that mold from noe, by the way, how many grains is the mold you ordered? which 6.5 are ya shooting? have a good'un!-Travis
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  12. #12
    Boolit Master quail4jake's Avatar
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    This is a 6,5x55 Mauser and the boolit is the 270-149 RN GC from NOE. There is a great thread on Cast Boolits from 2005 about H. Guy Loverin, educational and comical. Best of luck!

  13. #13
    Boolit Master Oklahoma Rebel's Avatar
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    Quote Originally Posted by Oklahoma Rebel View Post
    do you guys think the loaded OAL of this boolit/cartridge, crimped in the crimp groove, of 3.181 leaves enough room for loading considering the saami length is set at 3.291? I am just a bit concerned that the meplat may cause feeding issues, so I made sure to give it a bit of extra room. I know you can only give a educated guess answer because all guns are different, this one being a CZ550FS 9.3X62.
    is .11 giving the cartridge a reasonable amount of extra space to feed that flat point?
    An armed man in a citizen.
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  14. #14
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    it depends.
    do the feed rails aim the nose of the round up, or does the bolt just push the round forward and rely on a feed ramp to guide the round into place.

    I will tell you the secret to the multi and long drive band bullets.
    it has to do with metal displacement and [dang I forgot the word but it occurs from the back of the accelerating bullet]
    anyway your moving stuff under pressure, allowing it somewhere to go without distortion makes the difference.

  15. #15
    Boolit Master


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    Obturation?

  16. #16
    Boolit Master Oklahoma Rebel's Avatar
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    yup! that makes sense, and as it does so a loverin design would seep lube from almost its length also it spins of and some sprays forward with any gas leakage. it is mauser type action, I think its called controlled feeding? the rim slides up under a big claw and I think the cartridge points up a bit. like ii said various disasters have delayed the buying of the gun
    An armed man in a citizen.
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  17. #17
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    it's slump.
    as the bullet is banged up by pressure the design of the bullet can change and the unsupported nose wants to stay where it is when the back of the boolit is shoved forward.
    if that area is supported then the slump is taken up and moved along.
    however if you don't have a place for that extra lead to go you end up with a lump of trying to be cylinder shaped piece of lead.

    I use a boolit design sorta similar to the one Travis show's but with stronger rear drive bands
    part of that is because I want a slightly rearward center of gravity and part is to move weight away from a less supported nose area.
    I can also rely on the big single lube groove to suck up the lead displacement and the area above the gas check to take up the displaced lead from the rear drive band.
    I'm however limited to long slow launches.

    now Gearknasher will like your design for the most part [no I didn't ask him] except maybe he would vote for some slightly stronger drive bands.
    he likes a crimp groove near the front just to insure the lead has a place to flow before hitting that middle drive band.
    but his launch system is just a bit more violent than mine is.

    the key to both systems is to make sure you are engaging the rifling and keeping it engaged without disrupting the shape of the boolit under acceleration.

    those loverign designs are there to be more extreme in the engraving process.
    they have plenty of room for the excess lead to flow but the entire bullet will change shape when fired at extreme speeds.
    the angles of slope built in allow the bullet to change shape predictably and reliably [slump into another shape] they ain't there to hold 1/2grain of lube.
    you only need to lube the bottom groove.

    the point of the whole thing is to get the bullet from the mold to the paper/deer whatever without damaging it.
    well that really doesn't happen so an appropriate design takes that change into account and allows it to happen, only it does so without really damaging the integrity or balance of the bullet.

  18. #18
    Boolit Master

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    I like to keep things simple. Bullet design is one of those that I barely have a basic understanding of. However I am more than happy to experiment with any bullet and powder combination to see if I can make something accurate. Never know what you might find.
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  19. #19
    Boolit Master
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    Elmer Keith was designing the perfect revolver boolit.

    He wanted a thick, square shoulder that would support a heavy crimp plus the ability to fill the chamber throat and jump straight across the cylinder gap into the forcing cone with a minimum of gas blow-by. What lube was necessary only had to deal with 6 or 7 inches of barrel.

    A rifle boolit needs to fill the leade, perhaps support itself on the bore, certainly fill the grooves without slumping or deforming, and stay lubed through 24 inches of barrel, sometimes more. Here, multiple smaller grooves do the lubing duties without the potential of collapsing and distorting the boolit.

    I’ve noticed that the Keith and “High Velo-Pen” designs with big/deep lube grooves give usable but unspectacular accuracy, at best, in rifles, while the Keith design, especially, shoots significantly better than others in revolvers.

    The only partial exception to this general trend is the “Big Lube” .44-40 boolit used in rifles with black powder. Cast oversized out of Lyman #2 type alloys, it deals with the BP fouling better than other designs and the hard alloy helps keep the lube groove from collapsing. So it shoots about as well as other designs with smokeless, and better than most with black.

    I’d go with the two grooves, myself.

  20. #20
    Boolit Master

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    To me, the number of grease grooves are only important in relationship to how well it shoots.
    But, even then, accuracy is more important than grease grooves.
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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check