Why are Lube Grooves the way they are?

[303Guy]

It seems to me that lube grooves are typically too wide and too deep leaving too little width to engage the rifling. Loverin designs seem better but still have narrow drive bands. So I'm wondering why the lube grooves shouldn't be shallower and narrower, perhaps with more of them?

[country gent]

Keep in mind the grooves have to carry enough lube for the trip down the barrel weather its a 16" or 34" length, the old maker dosnt know when they make the mold where it will be used, or what lube will be used. The grooves also have to allow enough area for the lube to grip and hold in. Lubes have to flow into these grooves also shallow wide grooves would up the pressure needed. Tumble lube bullets are coated completely nose bearing surfaces metplat base and grooves. The ration of groove to band also control friction in the barrel.

[JSnover]

What's important is the length of the bearing surface (with exceptions), I.e., the distance from the base to the front edge of the forward band. The amount of surface contact doesn't have to be all that much for most applications.

[Larry Gibson]

Most cast bullet designs are from "back in the day" when there weren't the modern lubes we have today. Unfortunately the designers of newer bullets look to the older designs for lube groove size, number and shape. The lube grooves for todays lubes (started with the classic NRA 50/50 lube) do not need to be ad wide or as deep as the grooves of old.....but they usually are. Lee started a more modern trend with the TL designs and narrower and shallower designs on his bullets. It was also thought back in the day that the lube grooves were supposed to collapse a bit and somewhat force the lube onto the barrel somewhat like a grease gun. With hard cast bullets that do not collapse and modern lubes it is found the huge, deep lube grooves are not needed.

Larry Gibson

[bhn22]

Yup, in a word... tradition. LBT uses really narrow lube grooves in some bullets, but by and large, people want to see the really large lube grooves that aren't really necessary anymore. Modern lube formulations are much more effective than beeswax and mutton tallow.

[longbow]

No arguments with what has been said but an observation or two. Elmer Keith seemed to like large square lube grooves in his "Keith" style SWC's and they work well in both handgun and rifle (in my experience anyway) yet there are also designs like Lyman's 311299 which has very little groove diameter bearing surface, relatively narrow driving bands, shallow and rounded lube grooves, yet that design is also a winner.

Also, many people say that using Loverin designs which have plenty of room for lube that they only lube one or two grooves which puts them in the same category of lube capacity that the 311299 has ~ small.

I have had no problems with my 316299 NOE boolits leading even with my home made lube so obviously they carry enough in a rifle barrel.

On the other side of the coin, I have had ACWW Keith 429421's collapse in the lube groove when using heavy loads (recovered boolits tell a tail). And when I say collapsed, I mean to the lands so that would certainly act as a grease gun and squirt about all the lube out. It can't be too good for accuracy though. I was doing penetration tests with those loads so accuracy was not checked. The fact that a book load of Blue Dot caused that boolit to collapse indicates that the alloy was not hard enough.

I have also had 316299's skid a bit showing wider grooves than lands in the boolit (again, recovered boolits tell a tale). Oven heat treating fixed that. A slower powder might also help if the acceleration is a little gentler.

My view is that many boolits have lube grooves that are too deep, leaving too small a diameter to resist the pressure of heavy loads. I think that if a boolit fits well, it does not take a lot of lube to make it through a barrel.

I guess I am with 303guy. I like a lot of bearing surface and relatively shallow lube grooves.

I am sure there are a lot of opinions here though. Different strokes.

Longbow

[btroj]

Only issue I have with some Lee moulds is the shallow grooves, they seem to be prone to letting to of the lube in storage.

Tradition is hard to stop in shooting sports.

[Mal Paso]

The market is controlled by the lube groove dealers.

A couple of the major loob groove dealers run this forum.

Just a word to the wise about being TOO critical of loob grooves.

[btroj]

So Waksupi is the Cheaper Than dirt of the loob groove world?

Can I be banned for saying that?

[longbow]

Oops! I meant to say "I love lube grooves! The more the Merrier!"

Are we good now?

[bhn22]

Nice recovery guys.

[GabbyM]

I've a couple rifle bullets with pencil thin lube groves. They do just fine.
Even the Saeco #243 which runs all the way down a 26” bore. My other 6mm boolit is a Lyman Loverin with lube galore. All that extra lube doesn’t seam to help or hurt it. Both bullets fail at the same velocity and powder charge. One is 87 grains the other 84 grains.

Maybe if you had a goofy washboard of a barrel surface. But really the gas either blows by to ruin the whole works or it doesn’t. I’ve never experienced much in between. Nor heard where a bigger gob of grease would fix that. Have heard the term “run out of lube”. When people get leading down towards the end of a barrel. However I’ve never been convinced that’s an accurate description of the problem being experienced.

Black powder boolits seam to benefit from great gobs of lard and wax. So perhaps the large grease groves are more of a holdover.

[prs]

My boolit's groove is bigger than your boolit's groove! Nah na na na nah na na na nah na....

prs

[Old School Big Bore]

My quarrel with most of the Lee designs is not so much the grooves but the bands. The front band is so dinky and hard to fill, you have to crank the heat and run the molds on the edge of warping to get a good fill, and then the boolits are so crystalized they look liable to crumble or shatter. Same with the base bands, they're so meager it's hard to get a sharp fill. Most of their designs would have benefitted from moving some lead from the center bands up and down to the base and front bands, using a taller groove. They got it right with their 45-200-SWC which is pretty much a copy of the H&G #68; if they had done that with their WCs and SWCs their boolits would have been easier to cast and perhaps more popular. ARRGH, this has turned into a Lee rant, I guess...

[waco]

So Waksupi is the Cheaper Than dirt of the loob groove world?

Can I be banned for saying that?

You can, and should be.......

[freebullet]

I can only add that with pan lube a large deep loob groov makes things easier in my experience.

[waksupi]

So Waksupi is the Cheaper Than dirt of the loob groove world?

Can I be banned for saying that?


Why, I oughta.........

[303Guy]

Thank you all. That's an interesting and informative insight.


I can only add that with pan lube a large deep loob groove makes things easier in my experience.OK, that was a surprise. I was thinking shallow and narrow grooves would be better for pan lubing.

I'm also surprised that wider bands make little or no difference. I was expecting deep and wide grooves to collapse easier, especially if close to the boolit base. I have observed lube being left in the grooves which may or may not get thrown out in flight.

What about the shape of the lube groove? Does it make any difference if they are square or angled? Square would increase the bearing area and would hold lube in better (as in preventing it from flinging out) but then angled grooves would fling it out more reliably.

[GabbyM]

Another thing that has not yet been mentioned.
Cutting tools are used to cut molds. There's a fact I wont have to don my flame suit for.
So you're grinding this cutter to make money with. Old mills used a thing called a cherry. Anyway you want it to last more than a few minutes. So do you grind a tooth on it that is .062" wide or .100" wide? Pretty obvious even to people who've not burned up a few hundred thousand dollars worth of tooling as I have.

Then you have the issue of being able to fill the mold when casting. Some of us know little groves need an expensive high tin alloy to fill nice.

In the end it needs to look like something John Wayne would shoot in a movie.
Then to be contrary . There are those Lyman molds with the little nose groves you couldn't fit a fishing line into.
Like my 225646. I know how they do that but I'm not telling. Can't understand why they don't charge extra for those however.

[eljefeoz]

Thanks for this.
I have asked this question in other places, and since this has begun anew, may I ask, how/what determines gas groove design?
Agreed, the mould manufacturer has to cater to a large variety of usage patterns ( and keeping economics as a priority) and lube.if one were designing a CB, for say a .309" or .286" smokeless load, to run with, say, NRA 50-50 or Ben's Red specifically, would the design parameters change so drastically? Yep, you guessed it, I'm a lube noob, and find it very therapeutic, making up lubes.
Cheers and TIA

[GabbyM]

Thank you all. That's an interesting and informative insight.

OK, that was a surprise. I was thinking shallow and narrow grooves would be better for pan lubing.

I'm also surprised that wider bands make little or no difference. I was expecting deep and wide grooves to collapse easier, especially if close to the boolit base. I have observed lube being left in the grooves which may or may not get thrown out in flight.

What about the shape of the lube groove? Does it make any difference if they are square or angled? Square would increase the bearing area and would hold lube in better (as in preventing it from flinging out) but then angled grooves would fling it out more reliably.

Square lube groves hold lube tighter. But are harder to fill out when casting. Plus don't drop from mold as easily as rounded groves. Dropping from a mold is the biggie. Skinny o ring sized channels of lube can tend to yank right off a bullet. That's why this forum has an entire category devoted to lube recopies. Add some lanolin or any of the other dozens of fixes for making a more sticky lube. All part of what keeps this site jumping.

[303Guy]

Good point there GabbyM. I'm planning to make moulds for myself using a groove cutting type boring bar so that would not be an issue. That's basically why the question came up. I must confess the Loverin design has a lot of appeal and is in fact what I'm planning on emulating. My plan is to step the boolit down in stages to fit the throat profile. But I need (or want) an understanding of why things are done the way they are and users are probably the best source of information (especially on this site where the knowledge, experience and logic base is pretty damn good).

[GabbyM]

Thanks for this.
I have asked this question in other places, and since this has begun anew, may I ask, how/what determines gas groove design?
Agreed, the mould manufacturer has to cater to a large variety of usage patterns ( and keeping economics as a priority) and lube.if one were designing a CB, for say a .309" or .286" smokeless load, to run with, say, NRA 50-50 or Ben's Red specifically, would the design parameters change so drastically? Yep, you guessed it, I'm a lube noob, and find it very therapeutic, making up lubes.
Cheers and TIA

Much of that simply is dependent upon what fits. So often things come in two sizes. To big and to small. Say your bullet body has a length of x. You want a lube grove width of y. Then you find 2y doesn't fit in x but 1y is not enough. So you end up with y+z. now and then xyz come together to make a fine looking boolit. It sells like hotcakes for a century no matter if it shoots for a hoot or not. About like a Ford Mustang. Things don't drive for nothing. But are perceived as cool.

[GabbyM]

Good point there GabbyM. I'm planning to make moulds for myself using a groove cutting type boring bar so that would not be an issue. That's basically why the question came up. I must confess the Loverin design has a lot of appeal and is in fact what I'm planning on emulating. My plan is to step the boolit down in stages to fit the throat profile. But I need (or want) an understanding of why things are done the way they are and users are probably the best source of information (especially on this site where the knowledge, experience and logic base is pretty damn good).


I’ve three Loverin style boolits. They are stubborn to drop from a mold. Simply due to all those groves. Tapered groves help immensely. Groves smaller at bottom than at surface. Thus a simple off the shelf circle saw on mandrel comes short. You end up needing a tapered cutter costing a pile of money or you grind it yourself to find the week is over and you’ve not put your product out the door yet.

The old style cherry cutter is hard to beat for a small shop with a knee mill. Thing is you can’t put some minimum wage fool or drunk relative on the machine then expect a cutter that takes a day to make to last more than fifteen minutes. If that long. Which is exactly why you don’t see bullet mold manufactures popping up like McDonalds drive ins.

About any tool grinding shop now days can make you a cherry cutter. Anything you can draw up on a CAD then send over the phone line. But there is that bill they send. Six axis CNC grinders don't come cheep.

[GabbyM]

If all you want to do is cut a mold now and then. Running them on a lath. Especially a single cavity that doesn't have to match up to a sister cavity. Is the easiest way to go. Just grind a set of bore bars and go with it. making multi cavity molds on a lathe is done with CNC lathes. Still not easy.

[303Guy]

Thanks, GabbyM. I'm always interested in how things are made. I haven't spent enough time on a lathe to become bored with it. Nor a milling machine. I have a lathe at home but only a small one (the largest bench top available). So, the more information the better. I won't be considering a multi cavity mold any time soon.

[monkeywrench]

If Elmer Keith said it. I believe it. That's final.

[JSnover]

Thanks for this.
I have asked this question in other places, and since this has begun anew, may I ask, how/what determines gas groove design?
Agreed, the mould manufacturer has to cater to a large variety of usage patterns ( and keeping economics as a priority) and lube.if one were designing a CB, for say a .309" or .286" smokeless load, to run with, say, NRA 50-50 or Ben's Red specifically, would the design parameters change so drastically? Yep, you guessed it, I'm a lube noob, and find it very therapeutic, making up lubes.
Cheers and TIA
Look up Mountain Molds (there are others but I designed my favorite mold using their site). Send them your question and please share the answer with us, I think it would be interesting to hear from a custom mold shop, what works and why.

[Mal Paso]

The current version of Lymans 429421 has a groove designed by the lubrication sales department. The 503 clone (also Elmer's) I shoot now takes a Lot less and I still get a good lube star at the crown.

Don't think Elmer intended it to have a reduced front band either.

[fredj338]

IMO, the less diruption you have in the bearing surface, the more accurate the bullet is likely to be. The grooves have to be wide & deep enough to hold a lube & the lube type could determine the depth of the groove. Why I prefer a single groove large enough to hold wax based lubes.

[nanuk]

Keep in mind the grooves have to carry enough lube for the trip down the barrel weather its a 16" or 34" length,....


But if the boolit doesn't collapse and force the loob to the barrel, all you are doing is carrying loob out the bore, and flinging it into the air.

and if the barrel is smooth, VERY LITTLE loob would be needed to seal the boolit, as the seal is pulled with the boolit....


I dunno, but it is interesting that some have said square, or flat bottomed grooves make a more accurate boolit than rounded grooves.

perhaps is it just magic??

[detox]

My most accurate .357 Magnum bullet tested has two shallow round cut grooves. RCBS 147gr 9mm mould #82077

[BABore]

A lube groove on a well designed boolit is more than just an afterthought. There are a multitude of things to consider. What is the boolits intended purpose, velocity range, bearing length, bearing surface, firearm consideration, and on and on. The shape, depth, width, and positioning of the groove(s) will determine how it distributes lube and even more importantly how you allow or not allow the boolit to upset or obturate.

Any 1st year engineering or architecture student knows about columns and their strengths. Rounded lube grooves offer the strong support of the Byzantine arch. Even a thinner base band will resist obturation with this type of groove. Lube pumping action is more restricted as well. Keith designed his SWC's with a deep, square groove for the opposite affect. The groove is more easily collasped to pump lube and allow the base to bump up to fit the large throats of his Colts (my opinion). The square cornered, flat groove is the weakest design in grooves and support columns. When you start angling the sides of the groove, you add strength and let the boolit release from the mold easier. The more angle, the stronger and easier it gets. If you want angled sides, but also want the groove to collaspe more readily, then you use groove depth as an aid. IMO the main reason you see rounded lube grooves or the flat bottom groove with a 25 to 45 degree per side angle is cutting tool integrity. The same goes for mold makers that limit the depth of the groove. It's not that they are experts in lube groove design. They just don't like breaking expensive tools inside mold blocks.

The depth, width, and placement of lube grooves can and are used to affect the balance and center of gravity of a boolit. For every boolit diameter and desired weight there is a bearing length that has to be considered. The rest is the non bearing portion of the nose and any bore riding length if it applies. Yes, a bore ride section is bearing length in terms of support in the barrel, but it doesn't require the same lube as driving bands. Based on the velocity range, barrel length and bearing surface of the boolit, you need a certain lube capacity. Noticed I switched terminolgy from bearing length to bearing surface. Bearing length is the total length including grooves. Surface is only the bands in contact with the barrel, added together. The lube capacity is based on the groove width and depth. Where you put that groove or grooves along the bearing length affect the balance and also driving band performance.

Quite a few years back I did some analysis on the original Keith boolit dimension. I modeled all of his semi wadcutter designs as solid models. All of the different calibers have almost identical lube capacities based on bearing surface. Bearing length as a percentage of OAL and CofG are also nearly identical. Not an accident I think.

The number of lube grooves can play an important part in the design and resulting accuracy. Smaller handgun boolits and certain rifle designs (silhoutte type) usually only have a single groove because that's all that will fit. Longer, heavier handgun, and more traditional rifle designs usually benefit from smaller multiple lube grooves. The lube capacity needs to be considered as usual, but you can error on the high side with mulitple grooves. You can choose not to lube all the grooves if it's not required, or you lube them all with a lube of lesser quality. The big thing is you have options. Once the base band, front band, and crimp groove (if required) are determined, the remainder of the bearing length can be made up of the desired lube grooves (capacity) and driving bands. They don't have to all be of equal lengths and usually are not if you are trying to juggle a proper CofG for the design.

When I was making molds I decided to run a little test with a 458 boolit design. I made up two 0.460 dia., 420 grain GC designs with a tapered bore ride nose. I turned the cherry's one right after the other and recorded all my setup's. Both designs had the same bearing lengths, bearing surface, lube capacity, crimp groove, etc. The only difference was the number of lube grooves and driving bands. One had a single big groove and two wide driving bands, the other had two grooves and three bands over the same exact lengths. The CofG's were both within a couple thousandths of each other. Cast from the same alloy they were within two grains of each other. I sized and lubed them with the same lube and worked up loads for both using multiple powders. With every load, the multiple lube grooved boolit out shot the single grooved boolit. 100 yard, 5-shot groups consistently ran 0.50" larger. Only one gun in one caliber, but worthwhile non the less.

[geargnasher]

Bruce, I have a question that has bugged me for years. I have a 35-220 and have seen excellent photos of the .30-silhouette. Both appear to have a small nick in the cutter in the center of the lube groove which leaves a slightly raised ring dead-center of the groove on the boolits. Is this intentional for the purpose of creating a more uniform crush area, as with other types of engineered, cylindrical crush zones?

Gear

[soldierbilly1]

My boolit's groove is bigger than your boolit's groove! Nah na na na nah na na na nah na....

prs

ahhh. groove envy. very pervasive billy boy

[felix]

The more weight on the outside of the boolit, the better. As well, the less weight on the inside of the boolit, the better. A general rule: Hollow points only shoot mo'better than boat tails only. That's why wheels prefer to have spokes instead of a solid mass. Therefore, multi SHALLOW lube grooves are most desirable whenever possible. ... felix

[cwheel]

I'm getting quite the education here, very timely discussion. Going to try to make my first set of mold blocks here, cut a cherry, make my first mold. My mill has set idle for almost 6 months now, and I can't seam to find a 38/.357 mold that I want to my next run with. The lube grove thing is one of my questions as well, the preceeding posts have answered my questions to the point I'm ready to give it a go. Single cavity first to test the design, 6 cavity once ( if ) the bugs are worked out. Thanks to the OP and all those who answered.
Chris

[Oreo]

A few things I haven't seen mentioned yet that I came across while researching the design for the 10mm wfn (Mihec group buy) boolit I designed:

When the boolit exits the muzzle ideally it should shed all the lube immediately, or carry it all the way to the target. Shedding being preferred. If the lube half sheds then the boolit is destabilized somewhat and accuracy suffers. Even if the lube is retained it may not be as perfectly balanced as shedding the lube completely thus the preference. So, you design for that but as was mentioned in previous posts there is some trade off because you want a boolit that will retain the lube in the groove till it is loaded.

Other considerations are that Elmer Keith tried a 90° square grease groove but the mold wouldn't release the boolits. There needs to be at least some draft angle.

Also, it seems that there are more forces pumping the lube then just compression of the groove. There is centrifugal force from the rifling as well as the acceleration of the boolit causing the lube to slosh toward the rear of the boolit. The gasses that blow by the boolit before the boolit is fully engraved in the rifling may also carry some lube forward of the boolit.

And finally, in my research I came across some mention of poor lube groove design causing diesel combustion of the lube (which was bad for accuracy.) This was mentioned in regards to lube grooves that were too deep and that the lube groove only needed to be just a hair deeper then the lands of the rifling.

[44man]

I don't like to horn in on anyone's business but I also deal in lube grooves. Postage is very cheap sending them!
I HATE one large groove just from an accuracy standpoint in my revolvers. Something else is going on I can't put my finger on and it might be balance.
I started to make two to three grooves in my home made molds and even though they carry the same amount as one big groove and the drive areas are also the same in total, they are much more accurate.
TL? One of my best is the RD 265 gr in the .44 but I refuse to unbless it with any TL. I use Felix and the bugger will hold 1-1/4" at 100 yards from my old SBH.
The Keith with the very huge groove will not go in my revolvers any more.

[390ish]

The only Loverin style mould I shoot is a Lyman 160 grain 8mm. I must say it performs better than just about any other rifle mould I own. I switch up between pan lube and Alox. The only difference I. An tell is the amount of smoke. I end up with Alox on the bottoms of gas checks and that makes for a bit of the smokey stuff upon ignition. I need to find a few loads to work up in 7.62x54 for Lyman 311284. It shot so well with full tilt loads out of a Krag. I am lucky enough to be able to shoot my surplus rifles at 150 yards and like to generate velocity to a degree that I am not too far from the distance shown on the iron sights when shooting. The 311284 has about as square of grooves as I have seen on a rifle mould.

[LuckySavage]

It seems to me that lube grooves are typically too wide and too deep leaving too little width to engage the rifling. Loverin designs seem better but still have narrow drive bands. So I'm wondering why the lube grooves shouldn't be shallower and narrower, perhaps with more of them?

'Cause Elmer Keith said so. :kidding:

[Garyshome]

In the end it needs to look like something John Wayne would shoot in a movie. I would like to watch some John Wayne stuff again it's been a long time, that is some good stuff!

[btroj]

Are multiple grooves more accurate partly because they give the lead moved aside by the lands engraving a place to go?

Could it be that a bullet with multiple grooves, with lube, make multiple small seals with the bore rather than one large one and this does a better job?

Lube grooves are large on many bullets because the bullets were designed decades ago. That doesn't mean it is best, or bad, it just is what it is.

Babore, what does your experience tell about the reasons why. Any clues?

[Oreo]

Its interesting to hear accountsof multiple lube grooves being more accurate then a single groove. When I was doing my research I found far more accounts of a single groove being more accurate and for that reason multiple groove boolits were typically loaded with only one groove lubed. I suspect there is not a clear answer on this issue.

As for grooves providing a place for lead displaced by rifling to go, I don't buy it. I don't want the lead to go anywhere. I want it to be swaged snug to the bore.

[felix]

.....the lube groove only needed to be just a hair deeper then the lands of the rifling.

Correct! ... felix

[felix]

I want ...the boolit... to be swaged snug to the bore.

Absolutely. Ideally, the lead should be tough enough that it does not puncture leaving fins at the boolit's tail. The composition of such can be found with combination trials in conjunction with the boolit's design for a given load-gun combo. ... felix

[62chevy]

... lube groove only needed to be just a hair deeper then the lands of the rifling.


Correct! ... felix

How much deeper? one or two thousands or more?

[btroj]

Those fins are what I was speaking of Felix.

So, grooves only .010 deep or so. Isn't it a bit tough to keep lube in the grooves? Unless the lube has some good cohesion it isn't going to stick together enough to stay put.

I doubt Lee uses grooves much deeper than that.

[BABore]

Bruce, I have a question that has bugged me for years. I have a 35-220 and have seen excellent photos of the .30-silhouette. Both appear to have a small nick in the cutter in the center of the lube groove which leaves a slightly raised ring dead-center of the groove on the boolits. Is this intentional for the purpose of creating a more uniform crush area, as with other types of engineered, cylindrical crush zones?

Gear

What you have there is a very "Ebay" rare example of a split lube groove design so upon compression the lube is pumped in a specific direction.[smilie=1:


This was one of the first cherry's I made for myself prior to making molds commercially. After turning to just over the desired size, I would hand polish with emery cloth starting at 80 grit and progressing to 400 grit. After fluting, deburring, and sharpening, what used to be a full round is now four very thin cutting edges of the original shape. That little ridge you see is the result of a very fine scratch that was never polished out. The bottom of a lube groove is one of the hardest areas to finish properly. As I progressed in my skills I was more careful and polished the cherrys out to 1000 grit. I also purchased some hard stick abrasives that were 0.5mm wide x 5.0mm high. they allowed me to get to the bottom of narrow grooves and finish them right. Personally, I preferred a little radial roughness to the bottom of a lube groove as the lube would adhere better. Customers like them mirror smooth sous they perty.:grin:

[Digital Dan]

Thinking that some moulds survive the test of time and some don't. There's a sign.

Most of what I've read in this thread centers around CBs and smokeless powder loads which generally have short barrels. Different metrics play in the BP world.

My .02 worth is a pragmatic approach; it works or it doesn't. Someone else will get different mileage.

[BABore]

Are multiple grooves more accurate partly because they give the lead moved aside by the lands engraving a place to go?

Could it be that a bullet with multiple grooves, with lube, make multiple small seals with the bore rather than one large one and this does a better job?

Lube grooves are large on many bullets because the bullets were designed decades ago. That doesn't mean it is best, or bad, it just is what it is.

Babore, what does your experience tell about the reasons why. Any clues?

It all depends on the boolit. Before you get to the lube groove(s), other design criteria needs to be met. Having some great LG's does little good if the front driving band skids because it's to short or the base band is too wimpy or too long. Look at the Lyman 358446. The LG's are adequate for the design even for the shallow round grooves. But look at the base band. It is longer than even the 358429. Heavy base and shallow, structurally strong LG's. Ever try to get a 358446 to shoot slow even with soft alloy? They suck! Drive it at magnum velocities and it begins to shine. Then the short front driving band skids and you can starve for lube in a longer barreled gun. You don't have these difficulties with the 358429. I could only get the 446 to shoot well at magnum velocity by using a tough alloy like 50/50, WD and using a super slick lube. It does ok, but other designs are better and easier to get to shoot. Likely why you always see them on the "For Sale" market.

If I were to remake the design, I would take some off of the base and add a portion back to a full diameter top band and a portion back to the band below the crimp groove. That would leave a distance to be filled with two LG's and a skinny DB, or a single, bigger LG. I would keep it simple and just go with a single LG and basically have a 358429 slightly light.

Hard to get into the minds of some of the older designs. Some are (seem) very well thought out. Others seem to shoot for a specific boolit length and shape with everything inbetween an afterthought. In some cases the LG size and capacity reflected the lube of the times and not letting go of the blackpowder era. In others it seemed like "Oh yeah, I better get a groove in their someplace". It's much easier to design a boolit when your going in with a specific goal in mind. Much harder to do when additional minds and goals are involved. Overall, when the design allows, the top and bottom bands are not sacrificed, and lube capacity is acheivable, I've found multiple LG's to be better. It all depends!

[felix]

Yep, grooves only .010 deep or even less, depending upon the stickiness of the lube (and land height and design). Tailor the lube to the boolit instead, starting with very shallow ROUND (high-angle) grooves using an offset "drill" idea. Stepwise, use a larger drill to increase the groove width for one location when considering a multi-groove when necessary via live testing. Any crimp groove should be the narrowest lube groove and no deeper than to hide the thickness of the cases used. Actually less depth as to just barely NOT allow the boolit to enter the case upon recoil. ... felix

Adding to what BABore has implied to me in his latest post is this: If the boolit is hard to size as compared to another having the same bearing surface, and tends to return to as cast dimensions after a day or two, that design would be chosen to test fire first. Statically, the best boolit will shoot best in outer space. Dynamically, the best boolit will shoot best at sea level AND at high altitude BOTH. ... felix

[303Guy]

I've experimented with a melt on lube and needed to fiddle with it to get the lube to fill the groove as it solidified. With this thought came the idea that shallower, narrower grooves would be easier to fill this way.

I've experimented with smooth sided boolits and dipping the nose in molten lube to leave a thick layer which would support the nose in the throat. The other thing I did was to 'glue' the boolit in the neck with the lube (this required using a card wad to seal the case). I tried knurling the boolits too. Recovered boolits sometimes still had knurling in the groove impressions. The only accuracy test I did was with the original un-knurled idea and it did seem to work.

So with the idea of pan lubing or hot dip lubing it would seem that multiple shallow grooves would be in order. It'll be too hard to make rounded grooves with a boring bar so angled grooves is what I'd go for. This thread has given me some insight so as to form a starting point.

I was wondering also how lube groove design would affect the BC of a boolit?

[Oreo]

Lube grooves reduce BC proportional to their volume (weight loss).

[longbow]

303guy:

I use a hot tumble lube method that I quite like. It seems to be working for me anyway. I use my home made lube in a cast iron frying pan... just enough lube to form a film on the bottom of the pan then put boolits in, let them heat for a minute or so then roll them around to get the lube distributed. Works very much like tumble lubing with LLA except no drying time. Just a short cooling time required.

it might no work well with some lubes but the one I made seems to be okay with repeated melting and reheating.

I've used this method with tumble lube grooves, regular lube grooves and knurled boolits. It works with all.

In fact, I have been getting quite good accuracy and no leading with my new Mihec 316410 130 gr. PB with standard lube grooves. Not talking benchrest accuracy here mind you, we'll call it good plinking accuracy ~ as good as any other method I have tried and good enough for me.

Now that the gun is scoped, I will do some longer range shooting off the bench to see if I can tell any difference between lubes and lube methods.

Smaller, fewer, shallower lube grooves should reduce drag and increase BC. The BP guys have played with microgrooves and no groove boolits in an attempt to get higher BC's for long range shooting. I think that is one reason PP is popular in BPCR ~ the smooth PP boolits have high BC's and no leading.

Longbow

[felix]

I was wondering also how lube groove design would affect the BC of a boolit?

As per boat tail, it just might help going through the sound barrier. Of course, BC deals with the slip stream shape more than anything else when weight is NOT taken into account, so who really knows? Maybe those who researched the Herter wasp bullet design way back in the day might shed some light on that specific factor. Maybe a penetration test would be a commensurate test assuming all boolits tested were of the same alloy. A trajectory trace would be a genuine test, depending on what characteristic is really being contemplated. ... felix

[Digital Dan]

The Lyman 257312 shoots 5 by 1.5" with LLA tumble lube from an ancient Marlin lever gun.

http://img.photobucket.com/albums/v298/muddler/Guns/IMG_2025_zps41d165eb.jpg (http://smg.photobucket.com/user/muddler/media/Guns/IMG_2025_zps41d165eb.jpg.html)

http://img.photobucket.com/albums/v298/muddler/Guns/5c1ce865-c76f-4d47-9893-ba72f3bd13c0_zps5eb32efe.jpg (http://smg.photobucket.com/user/muddler/media/Guns/5c1ce865-c76f-4d47-9893-ba72f3bd13c0_zps5eb32efe.jpg.html)

It shoots about the same pan lubed with SPG. The Ideal 257283 which is essentially the same bullet w/o the gas check does the same with a wide variety of alloys.

[10 ga]

If the loob gruves are shallow and narrow ya cant charge as much for them when ya sell them. Everybody wants deeper and wider!

10 ga

[felix]

Why sell something that works well? ... felix

[felix]

Apparently, that 257xxx boolit is a well balanced one! ... felix

[JeffinNZ]

Digital Dan: Your .25cal boolits have caught a dose of 'wobbly bottom syndrome'! I can see oval holes.

Back to the grooves, I agree on tradition. The theory of "if a little lube is good, a lot must be better". In actual fact I have found the opposite and use the least I can.

Of course the more grooves, the less alloy you use and being of good Scottish stock that appeals to me!

[eljefeoz]

Just a quick thank you to all.very educative.

[eljefeoz]

Look up Mountain Molds (there are others but I designed my favorite mold using their site). Send them your question and please share the answer with us, I think it would be interesting to hear from a custom mold shop, what works and why.
Thanks for that tip.
As a non technical person, I find the rationale(s) and explanations offered here -especially BAbore ,Felix et al,very interesting and informative.I am looking for a .423 mould,and have visited the Mountain Moulds excellent site. But to design a mold, even with all that software help, will be a daunting task, if I don't know what works,and what I should be ordering. I will lurk around and learn a bit.Right now,I think I shall be looking at a Loverin type mold for a .314 project...

[Oreo]

A good way to start a new design is to look at existing designs to learn what design aspects you like or don't / need or dont. It's perfectly acceptable to copy features that work and modify as needed. Start with a nose shape and boolit weight in mind, get it sketched up on the mountain molds site, and then work the lube groove(s) in.

[Digital Dan]

Digital Dan: Your .25cal boolits have caught a dose of 'wobbly bottom syndrome'! I can see oval holes.

Back to the grooves, I agree on tradition. The theory of "if a little lube is good, a lot must be better". In actual fact I have found the opposite and use the least I can.

Of course the more grooves, the less alloy you use and being of good Scottish stock that appeals to me!

Indeed, but their wobble appears to be consistant. Minor background on that is that the 257312 bullets were purchased prior to receipt of the Ideal 257283 mould. The purchased bullets stand out as the poorest quality cast bullets I've seen in every regard except that they shoot fairly well...despite the voids, slag inclusions and 3-5 grain weight variations. The bullets pictured previously are from the Ideal mould and do not wobble. They don't shoot noticeably better at 50 but might do so at 100. Given the same dispersion there is no indication of flyers as pictured above.

Such is the hazard of buying cast bullets.

[JSnover]

I scratched my head for a long time when I designed mine and came up with bigger grooves, but not because I wanted more lube. I calculated the "best" length for my boolit based on my caliber, rifling, and intended velocity (online calculators are a godsend!). Then I decided on the nose profile I wanted for my purpose. Then I increased the depth and width of my grooves to displace some of the weight; I moved it forward to get the right length. At this point all I can say is it is promising. I haven't been able to shoot it enough to know what it can actually do.

[Highwaller]

I just joined Cast Boolits and would greatly appreciate some help.
I'm not new to reloading and casting. I started hand loading in '65 and casting
in '70. Problem is, I've been out of the loop for the last 20 yrs. and am behind
the times. My interests (for now) center around the .444 Marlin cartridge.
I'll be shooting an 1885 High Wall with a Badger Bbl. Any suggestions and
experience using the advances I've missed in the last two decades will be greatly
appreciated.

Highwaller

[JSnover]

You have come to the right place, Highwller. Welcome aboard, good luck :)

[303Guy]

Welcome aboard Highwller. :drinks:

Would that be a 'normal' grooved barrel then? 44man has done a lot of work with 44's (revolvers) and would undoubtedly have some pointers.

[karlrudin]

My question about grooves is, why they are there in solid copper bullets when those bullets dont get lubed?

[detox]

My guess........................................assum ption......................not been confirmed.......not varified..........abstract speculation..................who knows?

[303Guy]

In solid copper bullets? Those are not lube grooves, those are there to allow the rifling to impress without swaging the whole bullet which would raise pressure somewhat. I day say lubing them (not filling them) might actually improve performance and eliminate copper fouling.

[eljefeoz]

My question about grooves is, why they are there in solid copper bullets when those bullets dont get lubed?

Driving bands. There's a 150+ page thread on accurate reloading, by Michael Mccoury,on his B&M magnums, and the research which led to adopting that design.
Cheers

[44man]

Welcome aboard Highwller. :drinks:

Would that be a 'normal' grooved barrel then? 44man has done a lot of work with 44's (revolvers) and would undoubtedly have some pointers.
I don't know what the Badger barrel has on the .444 high wall. My Browning has 8 lands and grooves in the 45-70 so it needs a boolit like a micro groove Marlin.
The BFR badger barrels have 6 lands and grooves like Ruger but are more concise with every BFR measuring perfect as advertised. They are also hand lapped.
Babore is precise making a design with a lot of thought but has found more grooves work better for accuracy. ME, I make mistakes cutting a cherry because I don't draw out a design, I cut where I think while on the lathe. I have no measurements at all on paper.
I made the .475 boolit with a narrow .080" base band and more GG's, (three) and it shoots so good with many groups at 100 yards of 1/2" that I made the .500 JRH boolit the same. It worked and I have so many boolits in the same hole at 100 it is crazy. WHY? I sure don't know why it works like it does but recovered boolits show no distortion. The PB is out shooting a GC boolit.
I made a boolit with shallow GG's and it sucks even though it looks the same.
The .475 boolit has kept shots on a 6" swinger at 400 yards, first a sighter, next 4 hit the steel.
My 45-70 boolit out of the BFR revolver will clang a steel ram at 547 yards every shot.
Don't ask me to draw a boolit or explain anything because I can't, it was pure LUCK and I don't believe what I read.
I sent boolits out and something was changed when a mold was made, they shoot good but just can't match my mistakes. I have no stinking idea why the narrow base band works so good or why more GG's work better.
I use as much lube as I can, can't see why anyone would short lube and leave a groove empty. If you can tell from that, your gun should be a nail driver at 500 yards.

[geargnasher]

The reason to lube only one groove is when the lube is incorrect for the purpose (most being used aren't ideal when you split hairs) and either one has trouble with lube hydroplane or purge in the barrel or erratic jettisoning of the balance (remainder) of the lube all the way to the target. With lube tuned to the purpose same as powder and charge weight, one can lube every groove on a Loverin and it still work fine.

Gear

[303Guy]

44man, might I suggest sending samples to someone to measure up?

gear, My first cast boolit attempt for one of my 303's was intended to use the hydroplaning principle. That's the one that had a thick coating of lube on the nose.

[Old Dawg]

I have recovered enough bullets from berms to know that most grooves are much deeper than they need be. All that lube still left in the grooves was unnecessary in the first place.

[popper]

Btroj - I did a 9mm design reducing the depth to 0.010". It shoots fine, with HiTek coating. I wasn't able to recover any to see the 'fin' on the BB. My present thought is to go BB even though culling is more difficult. I'm also thinking that a short shank GC design may be better, experimenting with that in 30/30. IMHO, the thin rear band just gets blown thru and pushes lube into the bore. Somewhat same opinion of multi-groove designs. That effect really sucks for PCd boolits. I recovered some FB 40SW. They all had the 'tail' from bbl sizing, I didn't see much rifling tail.

[Outpost75]

+1 on what Larry said. Adding to that, effective bullet lubes work on the boundary layer principle, the same as motor oil in an internal combustion engine. To prevent leading, the lube must flow and coat the bore, to provide prevent lead residues abraded from the bullet surface by friction or ablation from adhereing to the bore surface. It is the surface area covered, not the depth of the grooves. If you recover bullets in a water tank with lube still in their grooves, the lube is not working.

I have had Erik Ohlen reduce the depth and width of lube grooves to reduce the volume of NRA 50-50 lube used, with good results. With the H&G #50 in .38 Special, 50-yard grouping is improved by lubing only one lube groove.

I like LLA for most applications, but will fill a single groove, crimp groove and the heel gap in front of the GC before overcoating the entire bullet with diluted LLA for heavy loads over 2000 fps.

[44man]

44man, might I suggest sending samples to someone to measure up?

gear, My first cast boolit attempt for one of my 303's was intended to use the hydroplaning principle. That's the one that had a thick coating of lube on the nose.
I have but the design has been changed just enough. Base band made larger, etc. Damned it all to hell, I can't explain it. Just why does my narrow base band shoot so good?
I will not tell you I am smarter, only some luck fell in place ONLY from mistakes that I worried about after reading what was needed.
Gear has tried to explain lube differences and why one groove is enough but nothing I have found yet. Different lubes can ruin or turn your gun into a mosquito shooter. I have not gone far enough to say only one groove needs lube.

[longbow]

44man:

I'd be interested in seeing your designs and can make a 3D model from a photograph if you want one drawn up exactly as you make it.

All I need is a couple of good digital photos of the side view and a couple of dimensions taken with a micrometer ~ diameter and length mostly but more are better.

If you don't want to share, no problem. If you do, I am sure many would be interested. This is easy to do and I don't mind putting a bit of work into it.

Longbow

[geargnasher]

I'm also interested in your "luck" design, 44man, I remember you mentioning it and the narrow base band "mistake" many times. AccurateMolds will duplicate anything that can be drawn except for certain lube groove angles, hollow point, etc.

My next .38/357 Magnum mould will be a multi-cavity RFN with about a 45% meplat, and NOSE POUR.

Here's the dealie-o with lube: It really doesn't matter how or what it does provided it does it exacty the same way every shot. All the theories you read about regarding pumping, slinging, groove pressure, fluid seal, blowing past the boolit on ignition, dieseling, leaving a film behind, "wet point", matching lubricity/viscosity/specific heat/"melt curve"/liquifaction under pressure/to the load, film strength, long/short phase transition, muzzle jettison/fling-off, yada yada yada are all probably quite true and most are at play to one extent or another in all "systems". Unfortunately, no one I know has a foolproof method to predict how a lube needs to be formulated to meet the requirements of a given system because the problem is so complex and variable. Ultimately, one simply has to make a reasonable assumption, observe the results, and then make corrections as necessary.

"Boundary lubrication" is a term referring to the point where a lubricant has been stressed to the point that fluid film separation characteristics have broken down and metal-to-metal wear is about to occur. In greases, the solid lubricants like graphite, Moly disulfide, organic moly, and other organo-metallic compounds or even sturdy polymer additives like PTFE serve as final boundary lubricants when the oils have boiled off due to excessive heat or pressure/shock loading. Boundary lubrication is the last-ditch additive package to save parts from being destroyed. If one studies all aspects and definitions of fluid lubrication of sliding metal parts, it will be discovered that just about every description of grease/oil-type lubrication occurs when a boolit is fired though a gun, from initial "fluid film" through the "boundary" stage and a mix of everything in between.

Gear

[303Guy]

...but the design has been changed just enough. Base band made larger, etc.Someone thought it can't be right and made an 'improvement' which actually wasn't. There may be other changes as well which would be measurable. Perhaps sent samples of the original and the 'copy' to someone to measure. Something could be learned from it.

I'm particularly interested in plain base boolits and right there I can see more than one possibility. I'm in favour of nose pour too. A nose pour can be either a flat nose or a hollow nose. The hollow nose can't use a sprue plate though but is likely unnecessary.

[44man]

I will take pictures of my boolits for you. Day is done for now, made bean soup.
I can not measure or make drawings so you need to just look.

[longbow]

Don't need drawings but a diameter and overall length measurement would be nice. Do you have micrometer or vernier caliper?

If you have no micrometer or vernier caliper then the photos will have to do or maybe you can get someone to take a measurement or two.

I'd ask you to mail a boolit or two to me but that would be a bad thing as I am in Canada so you would be "exporting" reloading components ~ a no-no if you don't have an FFL and licensing.

Take the photos dead sideways so the flat ends of the boolit are just not visible. That will minimize distortion.

Longbow

[longbow]

Bump!

Looking for photos! I am curious.

[Mal Paso]

So am I. What kind of beans?

[Old Dawg]

Why do revolver bullets need all those grooves while pistol bullets of similar weight and velocity don't?

[Old Dawg]

Why are there 700-plus religious denominations in the United States? Same reason there are so many bullet designs.

[Sensai]

Will pistol lube grooves fit on rifle boolits? If you can't find .22 lube grooves can you just get .44 lube grooves and cut them in half? [smilie=1:

[Oreo]

Just cut them in half and install sideways. You'll be fine.

[popper]

BAbore - A few ideas as to why your short band shoots better than the long band. less lead tail at the base. FB 40 has a tail, GC recovered from a 308 has no tail. Lube doesn't make a tail. Large band FB won't shoot 'slow', big tail, too strong to compress the lube, with light load. My conclusion is the alloy and rear band size must be fitted to the pressure. Small shallow grooves only need to hold the proper amount of lube. Draft or V grooves are easier to make than rounded.