lube grooves and accuracy

[hiram]

I have seen boolits with 1 wide lube groove, and I have seen boolits with 2 narrower lube grooves.

Given one and the same caliber, weight, and boolit profile, has anyone ever checked into which style is more accurate?

[44man]

I have seen boolits with 1 wide lube groove, and I have seen boolits with 2 narrower lube grooves.

Given one and the same caliber, weight, and boolit profile, has anyone ever checked into which style is more accurate?
Yes but don't quote me.
I make my own molds and one large groove has never matched two or more. Even a TL, RD boolit will shoot great with a good lube that is better then Alox.
Boolit balance or lube distribution? Don't ask, no idea. I know I will never make another mold with one large groove.

[Marlin Junky]

I think base thickness and groove depth are more important than number of grooves but then again, it really depends on internal ballistics which can vary all over the map. However, I doubt I'll ever have enough time on my hands and money to back up my hypothesis.

MJ

[turbo1889]

My limited experience with ordering custom molds cut to my specifications indicates that a series of multiple narrow lube grooves and bands along the body combined with a thick base-band (for a plain base boolit) provide the best results.

One can go too narrow on the body bands and lube grooves in some situations. The standard Lee TL profile has bands that are only 0.01” wide with shallow V-shaped grooves that are 0.04” wide by 0.01” deep. For anything other then an oversize bore-riding section that is intended to engrave in the rifling those little bands are too narrow. For a tumble lube profile that must stand up to seating in a case neck without getting squeezed down in diameter when cast from hard alloy making the bands twice as wide (0.02”) is what I would suggest. For conventional type lube grooves I don’t like to go smaller then 0.05” wide body bands and lube grooves and I prefer sharp angled “Keith” type lube grooves that are at least 0.02” deep for conventional non-tumble lube grooves.

Ultimately, my preferred design that I have settled on is what I call a hybrid boolit mold that is basically a modernization of the old proven performance classic tapered Loverin boolit design. A base band that is at least 0.10” but not more then 0.20” thick, followed by a couple conventional lube grooves and drive bands that are between 0.05” & 0.10” thick, followed by a series of full diameter TL grooves (preferably shaped like 0.01” deep mini crimp grooves) with 0.02” wide bands between them that serve to fill the guns throat and double as a series of crimp grooves to allow many different crimping points for various throat depths, optionally followed by a series of smaller diameter TL grooves that are Lee standard 0.01” thick bands and are several thousandths of an inch over the minor bore diameter and are intended to engrave in the guns rifling if it is a bore riding boolit design, and finally a short nose cap on top of all that:

http://farm6.static.flickr.com/5176/5437753130_c92c83c91d.jpg (http://www.flickr.com/photos/54455625@N04/5437753130/)

[44man]

I think base thickness and groove depth are more important than number of grooves but then again, it really depends on internal ballistics which can vary all over the map. However, I doubt I'll ever have enough time on my hands and money to back up my hypothesis.

MJ
You will not believe my best revolver boolits. Base bands are smaller then those between the GG's.
The base on my .500 JRH boolit is .075" and .070" on my .475 boolit, both do under 1" at 100 yards. ALLOY!
Another junk theory that does not hold water! :holysheep
Large base bands are for soft lead that skids like mad.

[turbo1889]

Very interesting on the base-band issue 44man. So you are saying that a thin base band works just fine with hard alloy but doesn't work with softer alloy?

I think that would be an argument for a thicker base band if you wanted to use the mold with a variety of alloys but thin base bands are just fine (and possibly preferred) if you intend to use hard alloy only.

Also, does this continue to hold up with loads in bottle necked rifle cartridges or not?

[longbow]

An observation that may play into things here is that I have seen my Lyman 429421 collapse in the lube groove area with it's one large and quite deep lube groove.

Also, someone posted photos recently of some .357 boolits suffering from the same problem. I can't find the post though.

In my case the loads were fairly hot and the alloy was fairly soft so not too much surprise.

The lead can only take so much stress then it yields. When it yields it crushes and swells the shank which in turn produces more cross sectional area to resist further yielding.

My thoughts are:

- most large groove boolits I have seen also have deep grooves so relatively small cross sectional area at the shank
- most boolits with small grooves have shallower grooves so more cross sectional area, so will resist more load
- in both cases yielding will result in shorter fatter shank where yielding occurs but the longer shank is more likely to allow base tipping or off center distortion than shorter shank

I think more narrower grooves, even if they are as deep as a larger groove, would crush more evenly so preserving accuracy.

Remember, even low pressure handgun and rifle load pressures are well over the yield strength of the strongest heat treated lead alloy available which is about 12,500 PSI. The boolit is going to yield. What matters is how much and where the lead goes.

Longbow

[Marlin Junky]

Large base bands are for soft lead that skids like mad.

Or, perhaps the faster twists more typical of rifles?

MJ

[gray wolf]

Does it make a difference for a pistol bullet ? I ask because I am thinking of the H&G #68 SWC
and some other pistol bullets with one GG.

Sam

[44man]

Or, perhaps the faster twists more typical of rifles?

MJ
Nothing faster then BFR twists! The 45-70 is 1 in 14" and the .475 is 1 in 15". Both will out shoot rifles. I forget the .500 JRH twist but it should be 1 in 15".
I am going to tell you the honest truth. I cut the cherries and made the molds before I found the base bands were small. I believed all the written word until I shot the boolits. Yes, I cussed until I seen what they did and I will never change my boolits.
I made molds with one large GG and a fat base and they do not come near what my "wrong" boolits do.
I have no idea, don't ask, I can't explain it. I do things the stupid way. I cut cherries by look, never paper pictures. Plunge in a GG here, looks good! I have no idea what the boolit will weigh.
When they go in one hole at 50, is it any wonder I buck the written word?
Ask me to design the perfect boolit----ARE YOU OUT OF YOUR MIND?????:kidding: throw out the pictures and be a stupid, lucky boob like me.

[turbo1889]

Does it make a difference for a pistol bullet ? I ask because I am thinking of the H&G #68 SWC
and some other pistol bullets with one GG.

Sam

My experience is much more limited in pistols then in rifles. That said I usually have better results in my 357-mag with boolits that have two or more lube grooves over single lube groove boolits. Doesn't seem to matter with the 38-spl. Possibly the pressure level difference between the two ???

[turbo1889]

. . . throw out the pictures and be a stupid, lucky boob like me.

That is basically what I did when I was first working with full bore solid shotgun slugs for rifled bore slug guns. I got some 5/8" diameter (0.625" = 20ga. rifled bore on the larger end of the spectrum) aluminum rod and stated cutting and grinding all different shapes and shooting them as prototypes from a 20ga. mounted solid to a 55-gal drum filled with concrete at a 100-yard target board and comparing group sizes. Once I figured out what worked and what didn't then I put it to paper and went from there to get a mold cut to cast lead slugs from.

[geargnasher]

I think it was BABore that did a simple experiment with two similar boolits in a similar load situation, one having two lube grooves and one only one groove. His results, while very isolated, indicated that the two-groove outshot the single in that one instance. He drew no conclusions but posted the results to be interpreted (or not).

IME, with platforms capable of telling the difference with me pulling the trigger, the double-groove pistol-type boolit will outshoot the single, giant lube groove disigns pretty consistently. I don't know if it has anything to do with the base band or not.

In rifles, Loverin designs have always been the easiest to get to shoot straight, but I think it's due to the fully-supported, short, roun, nose rather than scads of grooves. I almost always found the best accuracy with Loverins while only filling the bottom two, or even just one, lube groove.

Gear

[cajun shooter]

It does depend on how the bullet is being used. I know that 44 man shoots handguns for the most part with smokeless powder. The question seemed to cover a broader area than that. If shooting BP then I have found at the shorter ranges that it's amount over number of grooves. Now that statement also has a different answer also when it comes to design. I have found with BP that certain rifle bullets with 4-5 lube grooves shoot better than one with just two at the base area. Again you have amount but it takes the lube grooves to spread it over a larger area with the driving bands giving needed support. None of the Lee bullets work well with BP because of the bullet design that has very shallow grooves that hold too little lube. Many years ago they had a writer of a gun rag do a test with the 38 spl WC bullet. To my surprise, his best groups were when only one lube groove was filled. Now his bullet was a cast bullet with four lube grooves that were of normal depth and width. I am not speaking of the swaged Speer bullet that has a shallow pattern and a lube coating over the entire bullet. I have seen this bullet shoot out the x-ring at 50 yd line. But as we all know what works in one gun might be different in another.

[pdawg_shooter]

By turbo1898: My limited experience with ordering custom molds cut to my specifications indicates that a series of multiple narrow lube grooves and bands along the body combined with a thick base-band (for a plain base boolit) provide the best results.

Gee, isn't that a Loverin design?

[Larry Gibson]

Alloy position in in the lube grooves with relation to center of spin from casting, sizing or set back during accelleration causing imbalance of the bullet can be greater in larger lube grooves than in multiple smaller ones. The imbalance causes inaccuracy in flight and obviously inaccuracy on target. Bullets with shallow multiple grooves will most often be more accurate like the Loverns are.

Larry Gibson

[Bass Ackward]

It's really barrel length.

Barrel length is the over riding handgun factor to longer range accuracy and flexibility.

Make a narrow base band and you better be accelerating that design real slow and ultra hard or you have had it. For what velocity levels are most cast bullets with one groove and one wade base band designed? How hard were they expected to be to do that? And what was the maximum barrel lengths on a handgun back then?

Then it's forcing cone length. What happens to lube exposed to heat and high pressure when the base breaks seal? What happens if you have two bands and the first one is already up the pipe protected by steel? Do longer, heavier bullets protect lube better? That bullet carries more lube under pressure till muzzle exit.

Get a long enough barrel on a handgun and you can do almost anything. Cut that same barrel back and you better shorten your range or accuracy expectations or get different opinions on GCs. :grin:

[44man]

It's really barrel length.

Barrel length is the over riding handgun factor to longer range accuracy and flexibility.

Make a narrow base band and you better be accelerating that design real slow and ultra hard or you have had it. For what velocity levels are most cast bullets with one groove and one wade base band designed? How hard were they expected to be to do that? And what was the maximum barrel lengths on a handgun back then?

Then it's forcing cone length. What happens to lube exposed to heat and high pressure when the base breaks seal? What happens if you have two bands and the first one is already up the pipe protected by steel? Do longer, heavier bullets protect lube better? That bullet carries more lube under pressure till muzzle exit.

Get a long enough barrel on a handgun and you can do almost anything. Cut that same barrel back and you better shorten your range or accuracy expectations or get different opinions on GCs. :grin:
OH, OH, I was expecting you! :bigsmyl2: Of course I can't make sense of what you said! :veryconfu

[turbo1889]

By turbo1898: My limited experience with ordering custom molds cut to my specifications indicates that a series of multiple narrow lube grooves and bands along the body combined with a thick base-band (for a plain base boolit) provide the best results.

Gee, isn't that a Loverin design?

And in the exact same post you reference just a few lines down I said:


. . . . Ultimately, my preferred design that I have settled on is what I call a hybrid boolit mold that is basically a modernization of the old proven performance classic tapered Loverin boolit design. . . .

So that would be affirmative. I just personally prefer standard type lube grooves inside the case neck and TL type lube grooves on the nose of the boolit that is outside the case rather then all standard type lube grooves as found in the classic Loverin design.

[geargnasher]

Turbo, I can see the micro-groove throat and bore-fitting portions of the boolit making it much more versatile since it could be made slightly oversized and engrave more easily upon chambering in several different guns, or with different alloys in the same gun.

I often tumble-lube bore-riders with 45/45/10 before applying gas checks and lubing conventionally, and when I can I apply the gas checks and push-through size to the correct dimension and then lube in an overize bas-first die. I'm thinking the micro-grooves would make this even more viable.

BTW, are you responsible for the multitude of these designs showing up on Accurate Mold's catalogue? I've been wondering who's design that was.

Gear

[turbo1889]

Turbo, I can see the micro-groove throat and bore-fitting portions of the boolit making it much more versatile since it could be made slightly oversized and engrave more easily upon chambering in several different guns, or with different alloys in the same gun.

I often tumble-lube bore-riders with 45/45/10 before applying gas checks and lubing conventionally, and when I can I apply the gas checks and push-through size to the correct dimension and then lube in an oversize bas-first die. I'm thinking the micro-grooves would make this even more viable.

BTW, are you responsible for the multitude of these designs showing up on Accurate Mold's catalogue? I've been wondering who's design that was.

Gear

Yes, indeed that was the main idea of that design from the beginning. I have had trouble in the past with the narrow little bands on the Lee TL profile getting squeezed down in diameter and making the boolits undersize diameter when seated in a case mouth just due to the neck-tension (using a TL profile with wider drive bands like the ranch dog molds alleviates this problem by the way) and I thought I could use this to my advantage. That combined with good results with the DD ring on a couple good NEI molds (good as in Walt not his daughter made them) is what led me to try that design idea. If one DD groove on the bore rider section engraving into the rifling is a good idea why not a whole bunch of them neatly arranged in a row? Then the whole problem I usually have with crimp grooves never being in the right spot for me along with the "crush to fit" properties led me to think about using a series of them instead of a conventional front drive band to fill the guns throat and provide a series of different crimp grooves to accommodate different throat lengths on different guns.

The secondary idea was indeed lube related. Specifically, that the conventional Loverin type boolits I was getting good results with previously had a problem in that often I would end up having to fill at least one groove with lube that wasn’t enclosed in the neck (only after figuring out that I couldn’t get away with less lube of course since sometimes I could get away with just filling the bottom groove or two that was inside the neck) and no matter what I did that exposed lube always seemed to attract all kinds of crud like a magnet that I did not want to be running through my bore. With tumble lube coating on the other hand it is possible to mix certain batches that dry to a hard varnish like finish and aren’t sticky thus allowing a lube coating that didn’t pick up crud. Now this does work on conventional Loverin type boolits as well of course as well but I liked the idea of having TL grooves on the part of the boolit outside the case that I intended to dip lube after the cartridge was loaded in such tumble lube mixes.

As to the mold designs showing up in the AM catalog that are of this type of design. AM#36-210C and AM#31-180B are mine. They were the first generation prototypes to test out the design idea and see how it worked, one revolver boolit designed to fit a revolver type straight cylinder throat and one bottle neck rifle cartridge boolit designed to fit a rifle throat with a bore riding section that was over diameter by a couple thousands of an inch to engrave in the rifling. I chose a 36-cal revolver boolit and a “fat 30-cal” rifle boolit because of the multitude of different styles and types of guns I have in those sizes. I got good results with both boolits and learned a few things too about how I could make the designs better. I’ve got a second generation rifle boolit design (the one I posted a diagram of earlier) sent into Tom@AM for approval but I haven’t gotten a reply back yet and it isn’t showing up in his catalog, but I’m probably just being impatient considering I sent it into him along with another design just yesterday. Now the AM#51-720W design isn’t mine but I think someone else copied my basic idea only in 50-BMG size. There was also another big boolit up there (I think 45-70) that wasn’t mine but appeared to also use the same basic idea but it isn’t listed any more and was removed from his catalog when he did that big update a while ago when he also got rid of everything smaller then 30-cal. It might have been a tooling issue because the reason he stopped doing stuff smaller then 30-cal is because he upgraded to larger tooling sizes; if I remember correctly it had a very pointy nose and although I’m not a machinist I think small tooling goes along with long pointy noses.

Long story short, I’m responsible for some of them but not all of them. There seem to be others out there using the basic idea as well. I’ve also got a second generation design that I want to try in the 9mm, 380, and 357-sig that has a bore riding nose like the rifle boolits do. I’m curious to see if a bore rider with rifling engraving bands will work in a semi-auto pistol or not. Haven’t sent that design into Tom yet though, I want the second generation rifle boolit to try out in my 30-06 and other non-fat 30-caliber guns first and my funds are limited so I can only buy a new mold every so often.

[geargnasher]

I like the idea very much, and I'm very interested to see how they work, and I appreciate the detailed explanation. I might try to trade you out of a few second-generation .30s to try in my new Winchester M70 .30-06. That gun is one of the very last run of New Haven guns, and is pretty much lousy, including the throat. I don't know what boolit would fit it. It has a ball seat that is very unusual to me, it carries .3105" for almost .100", then quickly tapers to .3095 for a short way, and THEN the lands begin to show up. None of the boolit designs I have quite fill it. It has a chamber neck of .342-344, a bore of .3015, and a groove of exactly .3090" so I can see that if the reamer had a .299 pilot it could have "wallered" a little, but the surface is smooth and the whole chamber measures round. It's the two-step, pause, and then the lands that gets me.

I, too, have the issue of the crimp groove never being in the right place, and although I seldom use it in bolt guns, it is nice to have with really slow powders or hunting ammo. I used to post-lube my bore-riders like you do, but that was before I started using 45/45/10. I used to just thin the liquid Alox with petroleum naptha, dip the boolits and the first 1/16" of the case neck, and hang them to drip-dry using clothespins and a wire strung across a corner of the shop. Back in college I used plain turtle wax, Alox, and the cheapest paint thinner I could find in about a 30/50/20 respective proportion, but for the bore-riders it never occured to me to pre-tumble until Recluse's formula came along. It is much faster and even less sticky to use that formula and method to tumble-lube once before checks/sizing/groove lube rather than post-lube just the noses with liquid Alox.

Anyhow, I think it's a great idea and can't wait to see if your guns agree!

Gear

[turbo1889]

Thanks for the kind words and info Gear.

As a side note, I don't want people to start thinking I'm getting a big head about "my" boolit design. Simply put, I've had good results so far, but one guy shooting his own custom boolit design through his guns isn't really a scientifically stable analysis of the design now is it.

Provided Tom gives me the green light on the G2 design specs and I don't have any more bumps in the road I would be more then happy to send you a handful or two as cast since I would welcome an independent perspective from someone like yourself that I respect Gear. I'll PM you when the time comes.

Now, there is a point I have been debating and haven’t completely decided on. For both of my G1 designs I specifically and deliberately chose a plain base and no gas check with the reasoning being that problems with the design would show up more prominently with a PB boolit compared to a GC boolit. Normally, for bottle neck rifle cartridges where I have a lot of case capacity to work with I have a preference for PB boolit designs since through the use of slower burning powders and a filler I can usually get a PB to do what I want it to do while saving the extra expense and hassle of a GC. Now I know that for the 36-cal revolver boolit a G2 design would include a GC instead of a plain base since I ran into troubles with it in 357-max and hot 357-mag loads that I believe a GC would have easily cured and those smaller cases don’t give me near as much wiggle room to work with slow powder and filler to solve the issues instead of using a GC. With the G1 “fat 30-cal” rifle boolit I really didn’t have any issues where I felt I needed a GC but at the same time only a few loads I tried didn’t make use of larger volumes of slower burning powders and/or fillers since I had a lot more case capacity to work with.

I’m considering paying the extra $15 to have one of the cavities cut with a GC shank for a two cavity mold that drops both PB and one GC boolits both for the advantage of doing a direct comparison and since I may want a GCed boolit every once in a while for loads that use a few grains of fast burning powder without a filler (10gr. of Unique load comes to mind) instead of my usual recipe of larger quantities of slower burning powder with fillers. What do you think Gear, would the extra $15 be worth it to you if you were the one ordering? Thoughts?

[geargnasher]

I would sure go for the extra $15 to have the option. I will cost five times that much to get another mould cut with the shank, so might as well do it now. My take on it is the versatility of the design, and the GC option only increases that. I totally agree with your approach of a casefull of slow powder under a PB boolit, or even using some compacting filler from the shoulder up, but sometimes accuracy falls off even with doing that before I'm at the velocity levels I might desire, and a check will bring the useable velocity envelope up quite a bit. For just punching paper at 1600 fps I can hold high or dial it in, but many times 22-2300 fps has a better trajectory for hunting.

Gear

[Bass Ackward]

OH, OH, I was expecting you! :bigsmyl2: Of course I can't make sense of what you said! :veryconfu


At least you tried to think about it.

Use the longest barrel possible for lead. It covers for the mistakes you make and makes you feel smarter. :grin:

[Bret4207]

I don't think there is a single "best". I think with all the variables involved, many of which have been mentioned, all we can do is narrow things down to generalities. Myself, I generally like Loverin designs, strong bases, strong bands, enough length to provide proper alignment. That's my biggest issue with the Lee grooves, even a seating die that's cocked off a little or TP that's off can wedge them in crooked and it's hard to see. Depth, width, number of lube grooves? I don't know if anyone can say THIS IS THE BEST! Some might try, but change the alloy or lube or barrel and it'll go to krap.

I think this question is one of those that's always going to have a lot of opinion involved.

[Whistler]

Use the longest barrel possible for lead. It covers for the mistakes you make and makes you feel smarter. :grin:

This statement intrigues me, as my "problem guns" are those with short barrels (2.5" - 4"). Whatever I do, I simply cannot get them to stop leading. I've tried soft lead, hard lead, reamed the throats, loaded light, loaded medium, loaded hot, tumble lube, conventional lube, light boolits, heavy boolits, .357-360"... you name it. They still lead in the entire length of the short barrels.

Can anyone explain as to why?

[44man]

This statement intrigues me, as my "problem guns" are those with short barrels (2.5" - 4"). Whatever I do, I simply cannot get them to stop leading. I've tried soft lead, hard lead, reamed the throats, loaded light, loaded medium, loaded hot, tumble lube, conventional lube, light boolits, heavy boolits, .357-360"... you name it. They still lead in the entire length of the short barrels.

Can anyone explain as to why?
I have to agree with my friend Bass. Short is a problem but also with jacketed.
Load "light" and just what do you do? You dump all the pressure at once. Medium is not much better. Loading "hot" with the wrong powder is as bad.
The boolit must fit. It must be tough enough to take the rifling, it must have the longest, extended pressure curve. Just how long is the curve in 4"?
Extending the curve with slow powders in short barrels is really funny.
As much as I hate to say it, some guns just need jacketed, they just plain lead up.
Maybe the worst thing is to look for super velocity in a short barrel.

[Whistler]

I use my snubbies for competition (service class) where the requirements are 158gn bullet going at least 500fps. I've tried pressure ranges all the way from 9000 PSI up to 16 000 PSI based on Quickload calculations and I've tried fast (like Vihtavuori N310) and medium (Like N320-N340) with pretty much the same leading in all cases.

[geargnasher]

Whistler, my wife has a model 36 Chief's Special with a 1-7/8" barrel. Once I reamed the cylinder throats to .3580" (they were .356-ish before), it quit leading. Mild to max, it just plain shoots. The only lead that sticks is just a bit in the rough-as-a-cob forcing cone, right where the lands ramp up, and only a bit gets stuck in the machine marks, that's all. I don't own any shorty magnums, but I can see it could be a loading paradox indeed. Perhaps a dual-reaction powder is needed, one that reacts like 296 until the boolit is nearly out of the barrel, and a second reaction that's endothermic and sucks down the pressure! Only in cartoons....

Gear

[Whistler]

I have my chamber throats reamed to .3585" and the forcing cone cut to 11 degrees.
I have also polished the machine marks.

Being a .357 Magnum chambered revolver, it may be a cartridge OAL dependent issue. I will try seating the .38 Special cartridges to .357 Mag OAL and compensate with more powder to reach the same muzzle velocity. Perhaps it will lower the velocity at the forcing cone and allow for a better seal.

[Bass Ackward]

I have my chamber throats reamed to .3585" and the forcing cone cut to 11 degrees.
I have also polished the machine marks.

Being a .357 Magnum chambered revolver, it may be a cartridge OAL dependent issue. I will try seating the .38 Special cartridges to .357 Mag OAL and compensate with more powder to reach the same muzzle velocity. Perhaps it will lower the velocity at the forcing cone and allow for a better seal.



Just understand that leading is separate, gun specific issue. Barrel length is a generality.

The point I was trying to make is that while a snub nose can be accurate, accurate has to be redefined in terms of range. You won't see too many on the line dinging the 200 m Rams. And what you "NEED" in the way of lube or bullet design in this discussion is totally dependent on ..... maybe I can use the word "exceeding the norm" for that gun.

Generally, the shorter the barrel you have, the more options you are going to need. The more finicky it will be to every factor of design. And GCs really help here.

If you get a much longer barrel it will be much easier and allow more ..... mistakes and operator error or ultimately result in better accuracy. The only way to ruin the advantage of a longer barrel on a handgun is to over match it to case capacity. Then you lose options again.

That's why barrel length is not fixed by definition. a 5" 45 ACP is a much longer barrel than a 10" 45-70 in terms of flexibility. Range ultimately defines the accuracy.

That's why we never speak the same language in these threads.