Lube grooves....

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Tasmanian Rebel
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Re: Lube grooves....

Post by Tasmanian Rebel »

Mike, I think you may be correct but frankly I don't believe I have actually looked at the bottom of the grooves under magnification. They are pretty shallow so probably doesn't make much difference. Someone here may have a diagram of Dan's Money bullet design and could see much easier.
Keith Lay
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Re: Lube grooves....

Post by Tasmanian Rebel »

Jonny,when I got into the sport in 2003 most shooters were blow-tubing between shots and big grooves were thought to be helpful. Over maybe a period of 4-5 years blow-tubing fell out of favor and wiping between shots became more popular-particularly in the west where single digit humidities were common and after a long string of shots the barrel would get so hot and dry you'd blow yourself blue in the face and you would still foul out. I still like to use a blow-tube for offhand shots as it's a lot simpler thing without so many moving parts but use a powder like Goex or KIK which seems to hydrate better using a blow-tube.
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beltfed
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Re: Lube grooves....

Post by beltfed »

The mini groove bullets I have designed have had a 10 degree taper on the grease grooves.
Easier release from the mold in addition to likely better "distribution" of the lube on the bore and release of the lube upon
exit from the muzzle. Dan T; had suggested a taper of the groove "wall" .
beltfed/arnie
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JonnyV
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Re: Lube grooves....

Post by JonnyV »

I've seen those photos of bullets in flight as well, and it's pretty certain that there will be a shockwave coming off the leading edge of every lube groove on a bullet...whether that helps or hurts I don't know....if you had chunks of lube hanging on to the bullet, and other chunks fly off on the other side, could you then end up with only a partial shock wave instead of a uniform one?

Maybe formulating a lube to fly off evenly and easily upon exit from the barrel would be of great benefit....if chunks stuck to the bullet on one side, they might destabilize the thing just by their weight being off-center....Somewhere else on this forum I read a comment having to do with "center of form" and "center of gravity"...there was also another discussion about how some lubes proved more accurate than others even though no leading was observed from either one....maybe the difference was how easily they were shed from the bullet once out of the bore? An unbalanced bullet is obviously going askew right?

I think the form tube experiment might shed some light, at least it would allow a guy to see if there's a pattern to how the lube sheds off the bullet...might make a good video too! I even have some old bullets lubed with Carnauba Red to compare too.....
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DAVE ROELLE
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Re: Lube grooves....

Post by DAVE ROELLE »

With CNC lathe bored cavities, groove shape should be easily controlled, and lots of shape options possible.

Perhaps collaboration with Shiloh could spark a research program

Dave
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powderburner
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Re: Lube grooves....

Post by powderburner »

Way back when i was shooting lubed bullets i got a victory mould with vertical sides on the backs of the grooves and a taper on the front of the grooves. It held a lot of lube and left a great lube star even at 100 degrees but would always lead.
I always thought the bullet was blowing the grease out of the grooves and didnt have a good seal in the bore. The pgt bullets shank was identical to this bullet except for straight sided grooves. It did not lead and also made a good lube star.
The theory to it was to get the lube out of the grooves on the trip down the barrel . I do think the leading was coming from blow by because the grooves wernt sealing the gasses.
I always felt the lube grooves with square sides acted like o rings and sealed the bore when filled with lube.
Fyrexel cut the volume of lube down on cast bullets and improved a curacy but he was also shooting smokeless two different venues.
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Etienne Brule
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Re: Lube grooves....

Post by Etienne Brule »

I looked back at some fired bullets in the snow a few years ago.

I had done this test to see any nose slump.

Original post:

viewtopic.php?f=2&t=26019



When I look again at those bullets, I notice that some lube is still in many grooves ...


I lifted the lube so it can be seen...

Image

So ... do they need such wide grooves ??? ... Too much lube ... ?? Any other conclusions ... ??

Gerald
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JonnyV
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Re: Lube grooves....

Post by JonnyV »

That looks like most of the lube is still present in the grooves… do you remember which lube recipe it was? How did those bullets perform overall? That’s a great photo…!
Etienne Brule
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Re: Lube grooves....

Post by Etienne Brule »

The lube is SPG.

About half of grooves of most of bullets are empty: some bullets have all their grooves empty

Image

Gerald
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Re: Lube grooves....

Post by DAG4570 »

The question is, did they loose the lube in flight or after hitting the snow? I don't think the lube would stick out like that while still flying through the air.

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Re: Lube grooves....

Post by Etienne Brule »

DAG4570 wrote: Tue Jul 20, 2021 8:54 am The question is, did they loose the lube in flight or after hitting the snow? I don't think the lube would stick out like that while still flying through the air.

Dave
Hi Dave,

The first pic: I wrote: "I lifted the lube so it can be seen..."

I sticked the lube out just before taking the pic...

Gerald
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JonnyV
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Re: Lube grooves....

Post by JonnyV »

In that second picture with the three bullets, it looks like all of them exited the barrel with full lube grooves as well… I can’t quite tell from the photo, are those lube grooves 90° or do they have an angle cut to them?

I’m starting to wonder if shallow round bottom lube grooves on the way to go…?? What’s the point of sending all that lube down range?
mdeland
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Re: Lube grooves....

Post by mdeland »

Gerald, could I talk you into measuring (mic-ing) the width and depth of the grooves in the fired snow bullets and compare them to freshly cast bullets. Also could you check to see if each groove farther along on the bullet are all the same as before? I'm curious to know if the lube grooves have compressed at firing or if the lube maintains their size and shape and if the grooves closer to the base show any more compression than do the grooves farther forward.
mdeland
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Re: Lube grooves....

Post by mdeland »

A couple of observations I've made is that most leading in my barrels occurs in the throat area and I used to think this was caused primarily by gas leakage but then I began to realize from looking through bores with a Hawkeye that leading seemed to occur near any constriction in a bore, usually right at or just after it begins to open up again.
Now in the throat area with black powder use I now believe the front of the powder column itself along with the wad and bullet base completely seals the bore from from gas blow by for several inches until the front of the powder column is burning and it is the constriction of the throat itself that is pealing off the lead and soldering it to the bore wall.
When one thinks about it, leading is nothing more than high speed soldering . The three prime ingredients to make a good solder joint are heat, flux and lead/tin solder. All are present in cast bullet shooting with in the load, (heat from friction in the throat, the lube is the flux and the bullet the solder.
The plug gauges I have are what began to show me the apparent correlation between constriction and barrel leading when it's occurring up bore . The first constriction in any bore is the throat and that is where most of my leading occurs. I'm still investigating what I think is happening here but I've seen it enough to be reasonably sure this is the event chain that is the primary cause of barrel leading.
Etienne Brule
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Re: Lube grooves....

Post by Etienne Brule »

mdeland wrote: Tue Jul 20, 2021 12:52 pm Gerald, could I talk you into measuring (mic-ing) the width and depth of the grooves in the fired snow bullets and compare them to freshly cast bullets. Also could you check to see if each groove farther along on the bullet are all the same as before? I'm curious to know if the lube grooves have compressed at firing or if the lube maintains their size and shape and if the grooves closer to the base show any more compression than do the grooves farther forward.

Not so easy to measure... with the groove angles ...

Gerald

Image
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