Paper patching CJ bullet from .358 to .366

[303Guy]

That knurling tool does a fine job. The difficulty mentioned of aligning the subsequent passes could be solved with a grooving tool. Such a tool could be made easily if one has a lathe - which I do. But that knurling sure looks good and can only work well.

[longbow]

I made my own knurling tool (not fancy but functional) and it works pretty well. It started out life just as you say as a grooving tool. I wanted to make "tumble lube" boolits out of the smooth boolits I get from my push out moulds so made a ribbed/grooved roll using a threading bit to create a rolled microgroove surface looking a lot like the Lee tumble lube boolits. This worked exceptionally well giving as good accuracy as GG boolits.

I found though that due to lack of grip the grooved roll would slip occasionally ruining a boolit. The more I used the tool the more it happened. Likely the surface roughness from machining smoothing off or filling with lead bits. In the end I decided to go with knurled rolls and that worked too so I stayed with that.

I've often wondered why the knurled surface isn't more common but I guess just casting GG boolits is easier when a guy is buying a GG mould. For me, I make the smooth moulds so wanted to get better/easier lube than grease cookies or extremely thin tumble lube (this being for bottle neck cartridges).

Lately I have been thinking of a hybrid roll using very narrow ribs then running a knurl over those to provide some traction on the lead. I like the grooves in some ways better than the knurl.

Lead Pot:

Do you knurl up then size back a bit or just set the knurler to produce the size you want and if so how consistent is that?

Longbow

[Lead pot]

I start low and adjust up till I get the diameter I want if I have a undersized bullet. Once I have the diameter I want I lock it in.
I also have a Sheldon lathe that I make a lot of stuff with and I can make different knurl patterns or the amount of aggressive I want.
There is a benefit for putting a knurl on a GG so there is no bare lead in contact with the bore if the rifle has a history of smearing lead.
A heavy knurl.

Light knurl.

Or just changing a cast bullet that starts as a PP diameter to a GG diameter.

But why mess around changing diameter of bullets when the unchanged proper bullet works as well as these 12 rounds shot with the .50-90 Shiloh with one sight change at 200 yards.

[yeahbub]

Tammons, I'd say you're idea has merit. I'm thinking they might benefit from being rolled under a file to rough up their surface a la Ross Siefried's article. I can't think of a reason it wouldn't work just fine. I think grip is what you're looking for rather than diameter changes with file rolling. Let us know the results you get.