Tumble Lube vs Boolit Design

[steve4102]

I am told that the Tumble lube on the drive bands is what gives the bullet it's lubing properties and not the Tumble lube that ran over into the lube groove. Is this correct?

If so, then why the multiple lube grooves in Lee's Tumble lube molds? Would not a Tumble lube boolit be more effective if it had no grooves at all? Similar to the Precision Black Bullets design?

http://www.precisionbullets.com/

[WilliamDahl]

I would think that the lube grooves provide a place for the drive bands to deform into as it is basically being swagged while going down the barrel.

[longbow]

I am going to hazard a guess that most if not all the tumble lube is wiped off the drive bands when the boolit is seated. My take is that you just don't need as much lube as most boolit lube grooves provide and there is enough tumble lube contacting the bore to work even with regular lube grooves.

Don't forget that any bore riding nose is also covered with lube so helps too.

I think the tumble lube grooves simply provide a shallower recess for the thin tumble lube to make contact with the bore.

As for smooth boolits, again, most of the tumble lube would get scraped off when the boolit is seated. I have seen this first hand as I make push out smooth boolit moulds. Knurled lightly they work better with tumble lube than smooth boolits do.

Not sure about those Precision Black Bullets but that may be an epoxy coating or something like moly that doesn't wipe off easily.

My take anyway.

Longbow

[Airman Basic]

"Knurled lightly they work better with tumble lube than smooth boolits do."

That reminds me of some swaged lead bullets I got from Hornady, I think. Had a knurled bearing surface that would seem to work great with tumble lube. Wonder if there's a way to cast or swage those things at home?

[longbow]

Poop! It happened again!

I just responded and somehow my response got lost. Might be a senior moment but...

Anyway, I use home made moulds like the old Ideal cylindrical moulds to cast smooth boolits then use a home made knurling tool to lightly knurl them. Works pretty well.

Not saying I am going to beat the socks off the benchrest guys but boolits from my home made moulds shoot as well or better than what I get from commercial moulds from my guns.

The moulds are pretty easy to make if you have a lathe (I do).

I also made a simple knurler after trying plain smooth boolits with tumble lube. they shoot okay but I got some leading in my .303. My .44 Marlin did pretty well with smooth boolits but I used a grease cookie under them. Hard to do with a bottleneck case.

Anyway, that's what I based my comments on. I have made and shot smooth boolits tumble lubed and they work but tend to lead some unless there is a grease cookie under them. I think most of the lube is wiped off the bearing surface as they are seated.

For my .303's I made a smooth 314299 so nose bore rider with about the same bearing surface and shape as the Lyman 314299. It shoots not bad but does lead a bit even though the long nose bore rider is lubed.

A slightly different design with knurling does not and shoots very well for me.

If you can make or have a smooth cylindrical mould made, you can buy a knurler from Corbin:

http://www.corbins.com/hct-2.htm

They are a bit pricey so I made my own. I am cheap!

Longbow

[WilliamDahl]

If you can make or have a smooth cylindrical mould made, you can buy a knurler from Corbin:

http://www.corbins.com/hct-2.htm

They are a bit pricey so I made my own. I am cheap!


Interesting way of doing it. I was thinking more along the line of a pair of pliers with two half cylinder knurled sections that clamped around the bullet and gave it the knurled look.

[longbow]

I forgot on the second post... the simple approach is to use a coarse file and roll the boolit under the file and on top of a hard surface like a steel plate. Simple and effective. It puts enough "texture" on the boolit to hold the lube and brings diameter up a thou or two.

Maybe not quite as precise as a knurler but should be effective.

Longbow

[dromia]

My 310 Cadet boolits from a old Lee GB and an Accurate mould I had Tom make to the same design are smooth sided, I tumble lube them in Xlox or 45/45/10 and they work just fine up to 1250 fps.

Being a heeled boolit the lube on the bore riding part doesn't come off when it is seated into the case.

[steve4102]

I am going to hazard a guess that most if not all the tumble lube is wiped off the drive bands when the boolit is seated. My take is that you just don't need as much lube as most boolit lube grooves provide and there is enough tumble lube contacting the bore to work even with regular lube grooves.

Don't forget that any bore riding nose is also covered with lube so helps too.

I think the tumble lube grooves simply provide a shallower recess for the thin tumble lube to make contact with the bore.

As for smooth boolits, again, most of the tumble lube would get scraped off when the boolit is seated. I have seen this first hand as I make push out smooth boolit moulds. Knurled lightly they work better with tumble lube than smooth boolits do.

Not sure about those Precision Black Bullets but that may be an epoxy coating or something like moly that doesn't wipe off easily.

My take anyway.

Longbow


So, if most of the Tumble lube is scraped off during seating, how does it work? Is it the lube in the groove, the small amount left on the bands, or the entire bullet coating?

Some say they wipe the exposed seated bullet clean of all tumble lube, is this a bad Idea as it is needed to aid in lubrication?

[grumman581]

I forgot on the second post... the simple approach is to use a coarse file and roll the boolit under the file and on top of a hard surface like a steel plate. Simple and effective. It puts enough "texture" on the boolit to hold the lube and brings diameter up a thou or two.

Maybe not quite as precise as a knurler but should be effective.


I decided to experiment with this tonight to see what would happen, so I took a few tumble lube bullets out of my scrap pile and used a file/rasp that had 4 different profiles. I used the tumble lube bullets since they had the closest to a smooth profile of any of the bullets that I had on hand. The ends of the rasp/file had either a wood rasp profile or a course cut profile. One side was flat and the other side was curved. I think they call it a "4 in 1 rasp / file".

http://www.leevalley.com/US/images/item/Woodworking/Sharpening/62w3235s1.jpg

The above photo shows the flat file portion with a single cut file profile. The one that I have has a double cut profile.

I didn't even bother trying the curved side since I figured that it wouldn't be any use and all the examples that I had seen so far were with flat knurling on the bullets.

I tried it with an 18" piece of yellow pine 2x4 acting and a piece of 1/2" thick tempered glass acting as backing plates. The glass did not work good with either of the rasp/file profiles. The bullet would just slide across the glass and not rotate, so you would get a few marks on the top edge of the bullet where it was touching the file/rasp, but the bullet would not rotate so that you could continue marking it all the way around.

The soft yellow pine 2x4 provided better grip on the bullet, so it would rotate under the rasp/file. With the rasp though, the indentations that it created were too far apart, so I do not think that it would do very well. With the course file profile, it came out a lot better. The only possible problem that I saw was that the board started to get indented a bit after doing a few bullets, so it's *possible* that the board would eventually wear out. Of course, by doing it with only one file, you need to push twice the distance you would if you were using two files. Even so, the half length of the 4 in 1 rasp/file was long enough for a single bullet -- it's just a bit short to comfortably hold in two hands.

I think that you could knurl bullets pretty quickly this way if you used two course files, mounted one flat on your work table and another to a block of wood that had a handle on the top of it (kind of like a clothes iron maybe).

How well a knurled bullet performs vs a normal tumble lubed bullet, I'll leave that for the rest of ya'll to decide, but it is possible to knurl the bullet with a course file.

[grumman581]

Well, I stopped off at Harbor Freight this evening and picked up 2 identical course files. I rolled a few bullets between the two files and this is what I came up with:

80428

The alloy is water quenched wheel weights with no added tin. I believe that the mold that I used was the Lee TL452-200-SWC. I suspect that I did not press down hard enough on the first couple of attempts. The bullets have not been lubed yet.

[steve4102]

How does that affect size?

[grumman581]

How does that affect size?

I did not take before and after measurements, so I don't know. I'll try it again later and take those measurement.

[grumman581]

OK... Got a chance to take some measurements today for .45ACP bullets before and after knurling... The source bullet was an as-dropped water quenched wheelweight alloy bullet from the 6-cavity Lee TL452-200-SWC mold. They had not been resized nor lubed prior to this. Here's the results for 4 tests:

.458 -> .464
.453 -> .458
.452 -> .457
.453 -> .457

That first one was a bit large... Probably didn't close the mold tight enough when I was casting...

[longbow]

My original knurler was designed to make "microgrooves" kinda like Lee tumble lube grooves but much narrower. The goal was to put a fairly deep set of close spaced narrow grooves in the boolits. It worked but I got too much skidding and a bit of skid resulted in a ruined boolit.

That knurler raised diameter by up to 0.003". I even used it on "J" bullets for my .303. Some Federal factory rounds were shooting very poorly so I pulled bullets and mic'd. They were 0.311" which is a tad small for my Lee Enfields. all of which run around 0.314" groove diameter. A trip through the knurler brought them up to 0.314" and tightened groups up dramatically.

I was not after the diamond knurl, I wanted grooves but in the end the skidding beat me and I have gone to a slightly different set up that puts narrow diamond grooves in now. Still seems to work fine but doesn't raise diameter as much.

As for the tumble lube wiping off question, my take is that most boolits have some nose bore rider portion and that helps lube by leading the way. Also, regardless of how tightly the boolit seals it still leaks gas so I am convinced that the leaking gas picks up some tumble lube from the grooves. In any case, some tumble lube in regular grooves will contact the rifling.

An example of how much lube effect you can get form a nose bore rider ~ I made a smooth push out mould modeled after the Lyman 314299 which has a long nose bore rider and driving surface that if groove diameter. I tumble lubed these then loaded. Of course most of the lube on the bore diameter surface wiped off and pulled boolits showed a virtually clean surface (I am sure there would be a very small amount of lube left... but not much). These shot well without leading using moderate loads.

I decided to try dip lubing only the noses after loading to keep tumble lube out of my seating die. Well, the dip lube came out a little thick. Not super thick, just noticeably thicker than tumble lube. Accuracy was rather poor so I wondered if thick lube was too much of a good thing and scraped most off with my thumbnail. Accuracy returned. Boolits were likely floating on a film of lube and possibly even being hydraulically sized down due to thick lube.

As for file knurled boolits, I have tried that too and found that size did increase quite a bit but the little peaks were not too sturdy and flattened out easily so when seated, they "sized" back some. Effective diameter increase was only a couple though for what I did.

I am not about to say that knurling will replace cast in lube grooves but it does serve a purpose and works in some cases.

Also, I am not using LLA anymore, I make my own lube, melt in a cast iron frying pan with boolits laying in the pan then roll them around in the thin film of lube ~ what I call hot tumble lubing. So far it is working well for me for both knurled and GG cast boolits. And hot tumble lubing requires only a few minutes for the boolits to cool down so they can be handled and loaded, not hours to days of drying time.

Longbow