Nagging Question "Lube Grouve Locations ?"

[Ian]

Hell, I'd give a lot just to see the first 18" of travel out of the muzzle of any traditionally-lubed .30 caliber bullet fired at at least 2,000 fps filmed at 200,000 frames per second so the blowby and lube jettison could be observed. Sans that, I have to rely on my "Splatto-graphs" to capture the pattern and volume of lube at muzzle exit.

 

[fiver]

the best I have seen is a 22 lr caught in slow motion.
that little hollow heel disappears.

I'd like to see the first inch of travel in a clear barrel.

the best I have to go on is what happens when I swage a boolit in a swage die.
just bumping one up .001 makes some changes.
changing the shape of something like the 429241 to a rnfp makes some drastic changes to the rest of the boolit.
what impresses me is bumping a 324 diameter LEE style boolit up to 358 and how the little T/L grooves behave.

 

[9.3X62AL]

Another of the GREAT threads that get posted here.

I'm in elementary school comparatively speaking, as far as studying effects of the various forces in play when The Big Light hits the bullet base. On my gas check shanks, I have not strayed far from the Lyman form, that "fingernail's breadth" of clearance between the gas check lip and rear-most drive band. In my GC bullets, this has worked as well as can be expected. I don't ask a lot of my rifles with the castings--1800-1900 FPS only gets exceeded about 10% of the time.

I only have one bullet design with a larger gap, that being the Lyman #454490--a gas-checked 45 Colt SWC. I can't say that it shoots any worse or better than the #454424 or #454190 in revolvers with decent dimensions. Interestingly, "490" was the sole bullet that shot well from The Built Backwards Bisley with its .448" throats and .452" grooves. After the throats were improved, "490" shot about as well as it did previously. It still does, though I don't shoot many of them any more. In cast loads running 1000-1100 FPS, a gas check is rather superfluous. What does this "prove"? I have no idea, that is for the cats in the cubicle farms wearing propeller hats to figure out. Prior to the throat honing, I was happy that at least one cast bullet design shot worth a flop. Even jax were poetic downrange, and not a couplet in rhyme or a hint of iambic pentameter either. Aggravating stuff.

 

[35 shooter]

Fiver,

What happens with the tl grooves when bumped up like that?

 

[fiver]

they actually move but mostly retain their shape.
you just make a shorter fatter version of them.

I have had other designs that warp and twist the lube grooves when you push them like that.
I done one 44 bullet and the razor thin line of a lube groove looked like a Coca-Cola swirl.
it would somewhat be expected but it started full of lube.
it done it over and over again.
the thing was I fired them in my 24" lever gun and there was still enough lube there to do the job.

 

[35 shooter]

Thanks Fiver,

That's interesting, i was picturing them in my mind(not always a good thing for me to try to do) kind of clumping up and sort of just melding together.

Haven't tried any tl bullets in rifles yet...kinda, sorta interested in giving the new NOE rd 180 gr. tl a go in my .308.

 

[Bret4207]

Thing is, swaging isn't the same as the bump from a powder charge. It's kind of like the difference between peeing a rivet with a hammer or mashing it with a sledge. In both cases the rivet expands and moves, but you end up with 2 different forms in the end. That magic clear barrel would solve a lot of questions and probably show us some things we, or at least I, haven't quite grasped yet.

Wouldn't be much fun if we had it all down to a science, now would it?

 

[Brad]

Here is an interesting video.

This shows what kind of frame rate is required to see the bullet in flight. I bet a 20,000 fps rate with a good strobe would work.

Watch till towards the end. They show a short section viewed from the end of the gun where you can clearly see the bullet. As it rotates you can see debris flinging off in flight. This is with jacketed! Imagine what a cast bullet looks like with all that lube.

 

[9.3X62AL]

A very cool video. Many thanks, Brad.

 

[smokeywolf]

Always wanted to play with high speed cameras, but alas, that opportunity never materialized. Kept my ear to the ground for some years for an old Fastax camera.
The Fastax cameras are available now on "that auction site" for $200 to $300. Not sure where the 100 ft. rolls of 16mm double perf film can be had.

Problem with folks like us using a high speed camera is the expense of the film and processing.

With digital I'm thinking your storage device, probably a SSD (solid state drive) would have to be able to write something in the neighborhood of 4 gigabytes per second and that would be standard definition. For high def. your looking at closer to 12 gigabytes/sec.
Right now, the better SSDs are chugging along at about one half (0.5) GB/sec., which is just about what a 24P HD motion picture camera requires.

 

[JWFilips]

smokey....
Yes now days it is very easy digitally. We do high end HD video in my studio using a top notch Sony video camera. It is pretty amazing.
The new electronic chip drives are very fast and can easily record high frame rates