Shape of crowning tool

[Hal]

What shape of cutting tool do you use to cut the barrel crown with ?
Any other thoughts about cutting the crown.
Do you polish the crown to finish the job.

Thanks for you help.

Hal

 

[tobnpr]

I use this:

BARREL CROWNING LATHE BIT | Brownells

A difficult tool to grind correctly. These are expertly done to give maximum cutter strength and proper clearance as cutter tip enters bore and shank approaches barrel. By taking careful cuts and moving table back and forth, any degree of crown sh...

www.brownells.com

 

[jkohler]

i usually give mine crowns a touch with 600 paper after checking with a loupe

 

[B Nettesheim]

I grind mine out of hss, never got what I would call a satisfactory finish with carbide, ground like anything else but finish honed very sharp with a small radius. It doesn’t get touched after that.

 

[dnellans]

I use this:

BARREL CROWNING LATHE BIT | Brownells

A difficult tool to grind correctly. These are expertly done to give maximum cutter strength and proper clearance as cutter tip enters bore and shank approaches barrel. By taking careful cuts and moving table back and forth, any degree of crown sh...

www.brownells.com

“A difficult tool to grind correctly. These are expertly done to give maximum cutter strength and proper clearance as cutter tip enters bore and shank approaches barrel.”

As the cutter tip enters the bore???

 

[Dusty Stevens]

“A difficult tool to grind correctly. These are expertly done to give maximum cutter strength and proper clearance as cutter tip enters bore and shank approaches barrel.”

As the cutter tip enters the bore???

Theyre saying after the tip goes past the bore edge alot of tools will drag on the crown under the bore, so advancing the tip into the bore to advance toward the chuck to cut outwards most tools touch the barrel front under the bore

 

[Ksracer]

The small Micro 100 bars aren't terrible expensive. You can get them with different minimum radius, length, and nose profile.

A lot of people also use a piloted 60* center tool in the lathe.

Micro 100 BB-1801000 Boring Tool - Right Hand.180" Min Bore Dia, 1" Max Bore Depth.045" Proj.055" Offset.006" Radius, 1/4" Shank Dia, 2-1/2" OAL, Uncoated https://a.co/d/2ziN8Tl

 

[boltfluter]

Micro 100 boring bars are the way to go. Easy peasy and work great!
Paul

 

[LVLAaron]

You can get a solid carbide 6mm bar and a pack of brand name 25.51 inserts for less than a micro 100 bar... and it'll work better.

 

[GenePoole]

You can get a solid carbide 6mm bar and a pack of brand name 25.51 inserts for less than a micro 100 bar... and it'll work better.

Single-pointing a slight dish at 11° makes the best crowns. Even a regular small boring bar works fine. I like to leave a sharp transition (no chamfer, just hit with a bit of Scotch Brite to make sure there are no burrs). Some like a slight 45° chamfer which is probably fine.

 

[LVLAaron]

That's exactly how I cut mine. Slight recess, 11 degree.

If it's a barrel for me, I'll leave it sharp. If it's for not me, I'll cut a 45 chamfer just enough to get the lands and kiss the bore.

I'm probably paranoid, but I feel like sharp is better... but more likely to ding/wear out/whatever...

 

[gunsandgunsmithing]

Like many things, there's more than one way that has proven to work well. I prefer a very sharp hss tool bit for crowning. It's about the only thing I do any more with hss but it's my preferred method and tool for the job. I grind my own and polish it sharp and smooth. It requires touching up occasionally but no big deal. This cutter has one job and only one, and it never takes a heavy cut. Being really sharp keeps the heat down and lets me crown at high rpm, usually 1255rpm on the final pass.

 

[GenePoole]

I don't think they wear out. That particular barrel pictured was built for @avidflyer and has over 1500 shots and just a couple of months ago set a range record for the last f-class club match of 2022 at BRRC. 200-17X F-TR.

 

[butchlambert]

Many years ago Jackie Schmidt made a cemented carbide crowning tool. It works great. If you see this Jackie, will you post a description and pic?

 

[tobnpr]

A lot of people also use a piloted 60* center tool in the lathe.

?

 

[Ksracer]

?

Tool C in the picture. It's run in until it just cleans the lands up and breaks the edge of the bore. I suppose you could say that it really just breaks the edge, but I consider the last thing the bullet touches to be the "crown". In this case, the piloted tool cuts the crown and everything else is just the end of the barrel. Potato Patoto.

FWIW, I don't like the traditional "recessed" crowns on a muzzle that gets threaded. That lip around the edge turns into a carbon trap with a brake or suppressor.

 

[Judd]

@jackieschmidt

Many years ago Jackie Schmidt made a cemented carbide crowning tool. It works great. If you see this Jackie, will you post a description and pic?

Just put an @ in front of his user ID and the board will notify him he’s being “summonsed “

I just use a small boring bar...it’s the only thing it’s used for and it’ll do quite a few before she either starts screaming at me or crappy finish.