centrifugal force on lube

[bmortell]

calculated centrifugal force on the lube of a 44 250 k boolit with stick alox in the lube groove. calculating centrifugal force requires a radius .198 inch (center mass to center of lube) rpm 45,000 (1/20 twist vel.1250fps) and a mass .07g or atleast thats the best measurement i could get. so all this gives us 1.757 pounds force to jettison our .07grams lube away from the boolit. or in other words any given spot of lube has 11,000 times its wieght in centrifugal force. makes ya wonder how some comercial cast bullets have lube still on impact. feel free to double check after all this was one of those middle of the night hmm i wonder moments

[357maximum]

Please do not take this as being fecetious, but there is a member here who's signature goes something like this: "If numbers killed, I would hunt with a calculator".....alot of wisdom imparted in that short sentence. A paper target and actual field/range experience is of far more use than a calculator. Professor GUN is alot better at sorting the real world from theory than any numbers driven device.

[Wingnutt]

I've argued this point fer years now. A bullet will never travel for a minute, so why say it is going 4,500 rpm? Might as well say it is doing 270,000 revolutions per hour. For all practical purposes of a 1,250 projectile, its flight time at 100 yds is .24 of a second and will make approximately 180 revolutions. I just consider revolutions per minute as a misleading force in firearm ballistics....

[Larry Gibson]

Not sure what the OP is trying to say but centrifugal force does spin of lubes. Perhaps not all lube on all bullets in all circumstance but in enough that it can indeed have a "cause and effect".

Note the lube that spun off cast bullets on all 3 skyscreens and the diffusers. Start screen was 15' from muzzle.

Larry Gibson

Attachment 106018

[Wingnutt]

I didn't mean to post that I was going to argue, and I don't deny centrifucal force. I'm just saying not to blow revolutions to extremes by giving it a minute to fly downrange. A pistol shot at pistol distance, say 30 yds at 1,250 fps will impact about .072 of a second and will revolve close to 54 times. I'm not sure which is the greater force that expells the lube, but I would consider acceleration as a factor also...

[btroj]

We use rpm because it is a standard unit. Same reason we use fps when we shoot at ranges measured in yards.

Bullet lube needs to font off fully or it can unbalance a bullet. Nothing worse than finding lube boogers on a 100 yard target. Far rather get it on the chrono like Larry gets. Better yet is to have it gone before the chrono.

[bmortell]

just to clarify my purpose of this was to figure out how i found some buletts with lube still in the grooves. so i figured if i do the math of the force on the lube i should get small insignificant forces, really how hard do you think it would be to make wax fall out of a groove, not much i was thinkin. so i was suprised when 1 3/4 pounds couldnt remove lube even with the other factors. my angle of looking at this was its comparable to cd spinning at say 30k rpm, it doesent have to remain at that speed, as any period of time at that rpm will make it come appart

[M-Tecs]

I've argued this point fer years now. A bullet will never travel for a minute, so why say it is going 4,500 rpm? Might as well say it is doing 270,000 revolutions per hour. For all practical purposes of a 1,250 projectile, its flight time at 100 yds is .24 of a second and will make approximately 180 revolutions. I just consider revolutions per minute as a misleading force in firearm ballistics....

Only counting revolutions to the target doesn’t take in account the increased centrifugal forces placed on the bullet by increased velocity.

Most jacketed bullets don’t have any issues being fired out of a 7 twist barrel at 2,000 fps but a lot of them will come apart when fired at 4,000 fps out of the same 7 twist barrel. If you don’t like RPM divide by 60 and use RPS.

Other than RPM how else do we measure this force?

[btroj]

What lube? Some fling off, some stick tight.

357Max doesn't sweat it because he uses lubes that pretty much always go away right at the muzzle.

Don't get too wrapped up in this unless the target shows problems. Grouping issues or flyers could be signs of a problem.

Like 357 Max said, if groups are good don't worry what happens otherwise, the target is always gets the final say.

[Grump]

Anyone ever TEST accuracy of Boolits with a quarter or a half of the lube groove dry or less than half-filled?

I'm with the "results first" crowd, numbers are interesting and I play with them often enough myself, but really, what difference has it made on target. Btroj has a handle on this through his experience I presume, but what degree of flyers from unequal lube jettison are we talking about here? Is it the same for rifles and pistols? How far out of the group?

I had some truly spectacularly BAD accuracy/lack thereof from some .40 S&W "hard cast" commercial cast bullet reloads I bought maybe 10 years ago. Besides leading the barrel like a sewer pipe after maybe 20 rounds, I was finding blue lube goobers on the target fully 25 yards away.

[bmortell]

grump you test idea i found interesting, and since yall are saying we like boolits and targets not science data. i made 10 44 mag bullets that were 250k's ww+tin with lyman orange magic over 10.5gr unique. 5 were full of lube others were half filled (one side) shot from 6in and open sights aprox 25 to 30 yards. also i fired back and forth between each group as to spread any eye or hand fatigue evenly so to speak. the regular ones printed 2.030inch total group size, 3 measured .543 in the center of the group, one was to the right that i wouldnt of called as a flier. one was high that i would of called from eye fatigue. so from this i took that they would like to print 1.5 to 1.75 if i did my part perfect.

now for the interesting ones. total group size 2.715in none touching, spread randomly across the group. if someone could test with a scoped gun and two groups of each info would be much more precise. but i would say we have conclusive results so far. unequal lube jettison apears to deviate bullet path a couple moa in a random direction, in extreme cases mind you. but id imagine that could happen with a lube thats on the verge of holding on to the bullet. so choosing a lube that leaves the bullet quickly and reliably should give better groups all else bieng equal.

[Idz]

While the math may be right I think you are using the wrong physics. It appears you're calculating a point mass spinning about an axis when you have a spinning ring. The ring fails due to hoop stresses exceeding the tensile strength of the lube. You have to use the formulas from a text like "Roark's Stress and Strain" to get meaningful numbers.

[geargnasher]

grump you test idea i found interesting, and since yall are saying we like boolits and targets not science data. i made 10 44 mag bullets that were 250k's ww+tin with lyman orange magic over 10.5gr unique. 5 were full of lube others were half filled (one side) shot from 6in and open sights aprox 25 to 30 yards. also i fired back and forth between each group as to spread any eye or hand fatigue evenly so to speak. the regular ones printed 2.030inch total group size, 3 measured .543 in the center of the group, one was to the right that i wouldnt of called as a flier. one was high that i would of called from eye fatigue. so from this i took that they would like to print 1.5 to 1.75 if i did my part perfect.

now for the interesting ones. total group size 2.715in none touching, spread randomly across the group. if someone could test with a scoped gun and two groups of each info would be much more precise. but i would say we have conclusive results so far. unequal lube jettison apears to deviate bullet path a couple moa in a random direction, in extreme cases mind you. but id imagine that could happen with a lube thats on the verge of holding on to the bullet. so choosing a lube that leaves the bullet quickly and reliably should give better groups all else bieng equal.

I have done this and can confirm a .30-caliber rifle bullet can deviate as much as 1.5 MOA at 100 yards due inconsistent jettison. This is why I only use soft lubes and shoot through cardboard at point-blank range to ascertain the uniformity of the jettison and confirm that it all left the bullet in the muzzle plume.

Gear

[John Boy]

* Flame temperature of smokeless powder is about 2700 F
* Flame temperature of black powder is about 5250 F
Anyone know of a lube that melts higher than these temperatures?

Have I ever seen any lube from any barrel length with any twist ratio? NEVER!
Therefore centrifugal force on lube has absolutely zero impact leaving lube on a muzzle exited lead bullet

[M-Tecs]

* Flame temperature of smokeless powder is about 2700 F
* Flame temperature of black powder is about 5250 F
Anyone know of a lube that melts higher than these temperatures?

Have I ever seen any lube from any barrel length with any twist ratio? NEVER!
Therefore centrifugal force on lube has absolutely zero impact leaving lube on a muzzle exited lead bullet

John

I am not understanding what you are saying. The flame temperate of the powder doesn’t melt the lube or a lead bullet. As we know lead melts at 622 F. If you are stating some lubes don’t stay on the bullet you need to lead mine a pistol berm. Most of the hard lubes don’t come off.

[Del-Ray]

I love hard lubes. If the berm wasn't full of commerical cast hard lube bullets I'd have to use some of my own beeswax when I re melt them.

There are times I have to decant the wax floating on the top there's so much.

[gwpercle]

When melting down some range scrap I noticed some, but not all, the boolits had lube still in the grooves. All were commerical cast type with hard lube still in the groove. Either a hard red or hard blue. Didn't know how to calculate why it was still in there, but did come to the conclusion it wasn't flung off in flight or left in the barrel and I would continue using soft lubes in the hope some was coating the barrel. I always look for a lube star on the muzzel.
Gary

[runfiverun]

to much of a lube star ain't a good thing either.

[Grump]

BMortel:

EXACTLY the type of test I was interested in.

One variable I'm not sure of: Was your chosen lube one that flings off or one that stays put?

I'm currently using one that stays put, and recently had some small concerns about "how much" of a flyer I might be causing when ignoring the 1/12th or less of the circle gap in lube on a few of my "grade 2" boolits.

I know that the weight component of that small of a lube gap is quite small, lube being far less dense than any lead alloy...

Anyway, I would expect almost no accuracy/flier effects from a lube that fully flings off, even at 50% empty lube groove on one side...

Gear's report is for rifles at 100 using a fling-off lube that doesn't fling consistently. Now for all you winter-testing people in the Extreme Lube thread, does the firing cycle make every fling-off lube jettison regardless of ambient temps down to like Zero F or even 10 or 20 below??? My suspicion is that friction heating going down a rifle bore would equalize that out even for such a short exposure time to the heat...same for conduction of powder flame temp through the boolit to the lube mass. My understanding of low-temp challenges to rifle accuracy is that most if not all problems are from friction/lubricity/whatever of the residues left in the bore (what's his name's "C.O.R.E." principle).

Correct me if I''m wrong.

Thanks!

[runfiverun]

well one of our lube tweaks was to start using paratack it is a long strand binding sticky [it's in bens red too]
throughout the paper testing I noticed a pattern in the pic's gear and brad had posted and a trend.
I could actually count the lands and grooves in their guns [plus the rifling depth to an extent] without even knowing what brand they were.
we learned to control and manipulate the fling off by controlling the additions and the paratack level in the lube.
by making the fling off more consistent and into a finer spray the uneven ness with which it jettisoned affected the group size by allowing the boolit to become balanced quicker.
it made me a firm believer in adding poe type oils to my lubes too...