Gentlemen-

I have a question...

Do tumble lube designs offer an accuracy (or other) improvement over regular designs when using tumble lubes?

I can see that there may be more surface area for lube to adhere to however the way the lube does it's job must be different than the "hydrolic" method Veral Smith proposes for conventional grooved bullet designs. That method suggests that lube grooves must be full to do the proper job.

Thanks-

Sky C.

If the boolet is cast/sized to be .001 to .002 over groove diamter, then the tops of the tumble lube grooves are being crushed down - widening the supporting area - and much more so than with regular grooves because the slope of the grooves is shallow compared to the sides of the normal grooves (in many cases) perpendicular to the bore.

To me it means good support AND because the effect is dependant on only a few thousandths of an inch - the differences between barrels is likely to be very much in evidence. That also implies that a bit more experimenting may be needed to match the boolet to the bore and to find the right combination of alloy and powder.

IMHO.

SO -

what do the recovered bullets look like? Do they support the theory?

Hi All!

This probably 'bores' everyone to tears...so for the 2 people left reading....

I wondered about leftoverdj's theory on a gas problem. I think that may be a lot of it.

For my example..let us assume the folowing:

.357 bore and a tumble lube bullet that is .358 on front, rear and tumble lube bands

we are shooting this bullet at JUST below where a grease lube bullet would fail...

Let us use our mind's eye ( I love Shakespeare!) to slow the movement of the bullet as it leaves the case and first enters the bore.

Ok, here we go. The big light has just hit the back of the bullet and this bullet is 'floating' on gas as it leaves the case and enters the leade/bore. Gas is on all sides. As the slug moves forward, it finally finds a spot where the first band Seals the bore. So far-so good. The first band is constructed like a normal grooved bullet. The first band is big and strong enough to withstand this pressure without serious damage.

But the slug is moving forward. Now the first tumble lube band(TLB form here on) moves forward and seals the bore. For a slight instant, all the INCREASING gas pressure is on this band. Since we have already assumed that we are just below where the bigger bands would fail, this band will fail and let gas by.

I doubt it would fail all the way around...rather a weaker spot would let a 'jet' of gas past until the pressure equalized in the first 'groove'. ( this weaker spot could be an imperfection in bullet or bore.)

The first band is now damaged. But the bullet moves and the second band now must seal out what it cannot. The same thing happens to it. On and On and on...all the TL bands must fail somewhere- just like the compartments of the Titanic.

Finally, the rear band seals the bore and the bullet is on it's way...damaged.

We have started at the 'high end'. If we reduce the pressure until any TL band will not fail- that is probably the upper limit of the TL velocity.

My apologies to all... there are many more factors than the simple few I've listed. I just wanted this to be a starting point...

Yes, I have too much time on my hands to think...

Dale

...so it's critical that the boolit be the right size for the bore.



To big and it eat's up the grease grooves. To small and there is not an adequate seal. To soft, the bullet will loose it's shape and loose it's seal. To hard and the bullet won't obturate and seal.



The grease holds the integrity of the TL bands together as a gasket, allowing the bullet of the right size for the bore, and proper hardness for the powder load to do it's job.



There, the world is a safer place and I can once again- rest well..



If only I knew what I was talkin' about..

I have the TL 240grn Lee mould for the 44 caliber but have never been able to push it as fast as the plain base cast bullet out of the Lyman #429421 245grn Keith type bullet out of my 44 Marlin rifle for some reason. The alloy lead I use was about the same for both. I don't know why, it's just the bullet design I guess. BM

Bill

I guess I can chime in on this...

I've got the Lee 200gr tumble lube semi wad cutter in 45 for my 1911. I ran em through my Ideal luber sized to .454, with LBT soft blue lube.

I've lubed all but the top 2-3 grooves. Hasn't leaded yet, but so far my velocities are only bout 800 fps.

It makes a real clean bullet, and will be interesting to see how far I can push em'.

Mountiangun:


????? "when the groove diameter exceeds the bore diameter" ?????

Clarification please.

Thanks-

Sky C.

This is an interesting thread. Like the other posters, I've never seen a scientific inquiry into optimal tumble lube design.

Buckshot once mentioned an old Paul Matthews article where Paul experimented with groove diameter and found that performance degrades noticeably when the groove diameter exceeds the bore diameter. I haven't read the article myself, but find it easy to believe.

The Lee tumble lube bullets are intended to be shot without sizing, so they may be undersize for some applications.

What mountaingun meant to say was that Paul Matthews experimented with shallow depth lube grooves. When the bottom of the lube groove approached the lands, the bullet leaded the barrel and degraded accuracy considerably. When it touched the lands it did not shoot well at all.

I think I may have found that "magical" balance between the groove depth, barrel diameter, and bullet size with this Lee Tumble lube boolit.

The boolit cast at bout .454 with wheel weights, and the sizing and lubing barely touches the lead- leaving the gooves to hold lube.

But the bore of my 1911 is bout .452, so the sized boolit is about .002 bigger. I get a totally black bore, with no splash or streaks of lead what so ever, and it's turning out to be darn accurate.

This is a brand new 1911 with only 2 (factory test) condom boolits fired and so far I've fired about 120 lead tumble lubers.

Hi All! Another way to put this...Loverin designs are supposed to shoot well. The main differences between Loverin and Tumble lube designs 'at the groove diameter' are:

shape (one is rounded..the other square)
thickness (one is thin & the other is much thicker)
number of bands/grooves
lube type
(have I MISSED SOMETHING?)

What I am trying to say is this...imagine a TL bullet cast very near to groove size. The front band and the rear band are ok ...but...the TL bands are just barely supporting the bullet. The radius of the bands is all that touches the bottom of the grooves. In this example...the bands do very little to align the bullet...in fact the bullet MIGHT shoot better if .002+ oversize ...or if the TL bands weren't there at all...

here's a thought...is there a way to use the cad program to determine how much bearing area there is on just the TL bands to a depth of .001? .002 and .003 should be done also. These bands would have so little strength until the bullet shifted how much in the bore? .002? If you know the bearing area and the strength of the alloy...one should be able to figure or compare bullet alignment forces... I'm not smart enough but maybe one of you is...

The idea of the rifling bottoming out in the lube groove is an interesting one. If that premise of poor results is true...then TL bulets would ( and may) prove it... I need to think more on this...Dale

The reason was the accuracy of the Lee TL bullets. I can't remember exactly how fast that I pushed them but decided to use them for plinkers. Before I got the lubisizer, I tumble lubed all cast bullets with a mixture of alox and super moly. When I got the 245grn Lyman mould, I could barely catch the crimp groove and keep the OAL below 1.700". I was able to cycle the Marlin with a OAL of 1.690"+ so I went with that. I use the full power loads with H110-296, AA#9, #2400, LilGun etc. My favorite load is the 23.5-24.5grn LilGun and regular primer at around 1800fps with very little leading out of a hard alloy mix. I really haven't worked with the Lee TL's that much after I found such a accurate 100yd load with the Keith type bullet. My rifle has the 20" barrel with ballard rifling and a 1-38" twist. BM

Bill

another few thoughts...

I think the Lee production designs do the following... the front and rear bands steer the bullet in the barrell. The microbands present lube to the bore and little else. ( They do offer some bore riding benefit...but it should be nothing compared to what the groove riding diameter is doing.

I have pulled a few 'mistakes in reloading' and think the microbands are easily damaged.Damaged bands would have to degrade accuracy.

I would like to test my thoughts by designing an 8mm plinker.
Probably 150 grain @ .325. Mostly bore riding.It would be tumble lube but not with microbands. I would want the bands 3 or 4 times as big ( or more) with a noticeable 'flat' for strength. I would deem these bands macrobands....'big bands'.

Anyone have input?

Thanks, Dale

I wonder just how much lube is necessary. I have recovered bullets with full lube grooves...minus where the rifling imprinted of course. I don't remember having any trouble with those slugs. So I would have to 'assume' that 75% or more of the lube on the bullet is not needed.

I still think it may go back to the damaged bands and how they upset stable flight. I guess we should do some testing... increase velocity/pressure in steps and examine the bullets.Eventually, accuracy would degrade. Surely the signs of failure would be there on the bullet.

I also don't believe most bullet lube is needed. Having picked up a lot of scrap bullets behinds the targets I got to thinking. If all of that lube is still left in the grooves what did it lubricate? Did those missing chunks of lube come out upon impact or upon exiting the barrel. If upon exiting it must have left the bullet unbalanced.

It would be interesting if someone could test a smooth 'paper patched' style bullet with a dip lube.

Hi All! I guess I'll show my ignorance once again... Since Mr Lee designed these slugs, what does he have to say about them? I would think he done a series of tests...or at least had a lot of feedback from satisfied or unsatisfied customers. It might make for a real interesting evening to sit and chat with him....


I know the .38 and the .45 tumble lube designs do just fine at low pistol pressures...even in rifles. I have the trouble as pressure/velocity increases...

I finally got the benchrest built to do a little testing...but winter and work have interfered with my fun.

Mr Lee. If you ever read this, please post a reply and try to educate me...please... Dale

I shoot the standard RCBS 180 sp out of several '06's (up to 1800fps) with a thin layer of tumble lube on them. I do the same with the Lee 313 gr. 44. Good accuracy and no leading.

Hi doug!

Hi Doug!

I assume you have a gas check bullet for your '06 and are using the gas check? Just wondering...
Thanks, Dale

Yes, I use the gas check on both of thoses bullets. What I wanted to point out was that tumble lubing works with standard moulds (grease groove does not need to be filled). I bought a tumble lube 44 cal but have not tested it yet.

Doug

Hi DougH9-

Thanks for the input. This is what I was hoping to find out. I'm hoping to work up some loads with PB bullets and tumble lubing for some of my "fun" rifles. Wanting to find a way to process many bullets for plinking with less time invested in handling each bullet as is needed when installing GC's or running bullets thru a sizer.

Best regards-

Sky C.

Sky,
Like Doug, I tumble lube 'standard' boolits, and then run them thru a Lee sizer die. So far I've managed to avoid buying a lubrisizer, seems to me a damn expensive way to get some lube in the grooves. For higher velocity, eg 1700fps +, I find gas checks essential to prevent leading., and will often tumble lube twice.
Not as 'neat' as a lubrisizer, and I do have to wipe lube off the case neck after boolit seating and crimping using a turps dampened rag, but then I don't have $200 and then all the different dies for each caliber and nose shape invested. And reading here on the boards about all the time and trouble people have with them, just a whole nother piece of gear to fiddle and tweak and buy expensive bits for.
I have been experimenting with 'enhancing' the liquid alox formulation by thinning out my FWFL based concoction with some extra mineral turps and getting the TL lube a bit thickerer. I also find that using a heavy freezer bag for the tumble lubing itself gets a more thorough coating.
Sizing does seem to help in the interests of uniformity and concentricy in the overall accuracy stakes, and while a PIA, I'm a big fan of gas checks.
Cheers,
R*2