Knurling the boolit ?

[Traffer]

May not be particularly applicable to this topic, but you can "knurl" things by placing the item to be knurled in a vice with two files on each side in the jaws, tighten the vice just a bit depending on the material to be knurled & tap the end of the files towards the vice. The rotation of the item in the file "teeth" & proper pressure on it dependent on type of material, will sometimes knurl the item in between.

I recall some folks doing that to piston skirts to help keep oil up on the cylinder walls & piston skirts for lubrication. I reckon it would do the same for boolits, although I wonder if one did it for boolits that way & it might cause gas cutting if too far down on the base. Some folks will try this on some types of tool shafts to aid in gripping them when they are greasy/slippery. ( Think "drifts", screwdriver shafts & socket extensions for example).

Anyway, it was just a thought to share & if not applicable, then just forget about it. Consider it some possibly "useless" knowledge you now have in the back of your head, if ya did not know about it before. LOL

Your friends were some dam fine mechanics. Not many know that trick. The way I knurled the bullet in the picture was to lay the boolit on a file that was on a bench then take another identical file and roll the boolit between them. With a little practice it works very well. For those who want to hold grease on a 38 or any other long bearing surface slug (like a wad cutter) without grease grooves, this method may be just the ticket for you.
Fyi There is not much difference between knurling and canneluring a boolit. Knurling is more a term for making the checker pattern on a lathe though. Most people think of canneluring when making a pattern of cuts around a boolit or more likely a jacketed bullet. Cannelure machines are also used for making cannelure patterns on cases. They pretty much work the same though. By pressure they cut or mash dents into the bullet or case by rolling it between some type of forming tool.
Here is a link to a video I made about rolling a bullet between two files. I did a very poor job in the video but you get the idea here: https://www.dropbox.com/s/o8j2s3z0lu...Crimp.MP4?dl=0

[Ballistics in Scotland]

You can just lay one file on a table and put a bullet or two on it and place another file on top and roll them. If you place the files in opposite direction from one another you get a different pattern.

The tricky bit is knurling all of them to the same depth. A pair of metal rollers to determine the difference between the files would probably work

With rotary knurling devices, including proper lathe knurls, the depth of knurling determines the diameter, and thus the circumference. It starts out an irregular rough surface, and then settles down to regular knurling when the diameter becomes an exact multiple of the knurling pitch So the depth is self-indicating.

I think knurling would work with moderate pistol velocities, but wouldn't hold enough lube for a rifle bullet to reach the muzzle before running short. If you use a hard lube, the use of a toothed wheel in the bottom of lube grooves might reduce the tencency for it to break out.

[labradigger1]

Your friends were some dam fine mechanics. Not many know that trick. The way I knurled the bullet in the picture was to lay the boolit on a file that was on a bench then take another identical file and roll the boolit between them. With a little practice it works very well. For those who want to hold grease on a 38 or any other long bearing surface slug (like a wad cutter) without grease grooves, this method may be just the ticket for you.
Fyi There is not much difference between knurling and canneluring a boolit. Knurling is more a term for making the checker pattern on a lathe though. Most people think of canneluring when making a pattern of cuts around a boolit or more likely a jacketed bullet. Cannelure machines are also used for making cannelure patterns on cases. They pretty much work the same though. By pressure they cut or mash dents into the bullet or case by rolling it between some type of forming tool.
Here is a link to a video I made about rolling a bullet between two files. I did a very poor job in the video but you get the idea here: https://www.dropbox.com/s/o8j2s3z0lu...Crimp.MP4?dl=0

Knurling will increase diameter. Knurling displaces metal and it can’t flow in so it flows out.

[Traffer]

Yes knurling does increase the diameter. However, the knurled surface is also softer than without the knurl because it compresses down back onto itself. So the gain in diameter is not a big deal.

[Jack Stanley]

Knurling will increase diameter. Knurling displaces metal and it can’t flow in so it flows out.

Sounds like a good idea for low velocity and tumble lube if you don't want to leement the mold .

Jack

[reloader28]

Theres knurled bullets in my Speer or Hornady books. I always figured that was for lube

[country gent]

Swaged lead bullets have no lube grooves, lube grooves need to be rolled in or knurled afterwards to hold lubes. A lot of the swaged pistol bullets are knurled and dry lubed with mica. Another place it might help is with PC or high tech coatings. Knurling will increase the size. but the surface area is much less due to the diamonds so its softer and squeezes down easier.
The military converted some bigger pipe cutters to knurling tools for armorers to use to "fit" the op rod guides to M14s during rebuilds. The rolling between 2 files works for bullets also.

[Ateam]

I have used the file method to both increase the diameter of and achieve a better fit to sabots in smokeless muzzle loaders. Sometimes without the knurling, the projectile will "drill" the sabot, knurling gives it something to grab a hold of and usually fixes the situation.

[Ateam]

A word of caution.
I have seen aggressively file knurled J-words breaking off file teeth in the jacket (usually cheap Chinese files). This would result in a doozy of a bore scar if fired.

[Motor]

Knurling will increase the diameter of a bullet. I have knurled rods/axles when I needed a few thousandths to insure a snug fit. The cannalure tool will "cut" or "push" a groove in a round surface/rod/bullet just like a pipe cutter does (I actually made a "grooving" tool by dulling, rounding off the cutting wheel in a tubing cutter...).

Add to this list pistons for car and truck and other engines as well as valve guide bores and other bores. Of course doing small bores requires different style tooling.

For swedged or cast boolits it will increase the diameter and provide an excellent surface to hold lube and will be easy to size.

Motor

[longbow]

Corbin makes knurling tools to allow lubing of smooth swayed boolits.

I did the same thing for boolits from my push out moulds... look up Ideal Cylindrical molds. They were intended for PP boolits but if the mould is made about 0.093" undersize then knurled, it can be lived a
Then sized... or if you get it right just knurled, lived then loaded.

As already pointed out the pic in th OP is a cannelure tool but you can likely by knurling rollers too.

Longbow

[rmatchell]

The ch tool you have will work fine if you want to cannelure or even knurl if you wanted to reset it a few times, but your hands get sore after awhile with the small handle. Chuckbusters tool is hard to top for long term use.

On a side note if you want to tumble lube try mixing half a bottle of lee lube with a 1/4 pound of parfin in a pint jar filled with naptha. Drys hard and clean to load and shoot.

[DukeInFlorida]

Chuckbuster's Ultimate Cannelure Tool is absolutely the very BEST way to put a knurl on the outside of the cast boolits. He offers a diamond knurl wheel, in addition to the standard knurl/cannelure wheel. It would place a nice (approx 3/8") wide knurl on the boolit, which would give additional surface area for any coatings, such as the Lee Alox lube.

Chuckbuster is a Vendor Sponsor, and has his offerings here:
http://castboolits.gunloads.com/foru...06-Chuckbuster

[Digger]

Fascinating ....
so much info here with all this input .
Just another facet of our hobby/sideline for all to learn if not brought to light for others benefits ongoing here.
thank you much gentlemen !

[Traffer]

The tricky bit is knurling all of them to the same depth. A pair of metal rollers to determine the difference between the files would probably work

With rotary knurling devices, including proper lathe knurls, the depth of knurling determines the diameter, and thus the circumference. It starts out an irregular rough surface, and then settles down to regular knurling when the diameter becomes an exact multiple of the knurling pitch So the depth is self-indicating.

I think knurling would work with moderate pistol velocities, but wouldn't hold enough lube for a rifle bullet to reach the muzzle before running short. If you use a hard lube, the use of a toothed wheel in the bottom of lube grooves might reduce the tencency for it to break out.

Yup lot of room for experimentation in that. I thought of just using pieces of near .22" roller bearings to place between the files to act as stops so the crimp would be uniform between boolits. But I discontinued the experimentation when I started to powder coat. Powder coat works fine on the long bearing surface without any grooves or knurling.