Crowning Tool(s)

[Gary]

Finally got some time to make these for Crowning some of my old .22's, all single shot bolt guns. The double ended piece will be parted and the shanks reduced to approx. 3/8" to use in my drill. I have some fine valve grinding compound I plan to use as well. Lightly does it from what I hear. 60 degree on one end and 45 on the other.

 

[James Nicholson]

Since one is 45 and one is 60, do you use the 60 first and then the 45 to further clean up the crown?

 

[KeithB]

I recognize that brass! Good work.

 

[Gary]

You should Keith; the upper piece is yours and the lower is Waco's. Thanks again to both of youse guys.
James; I plan to use the tools as the existing crowned barrels allow. some of the existing crowns are cut so that a 45 degree tool wouldn't touch the area to be crowned/lapped.

 

[mattw]

Brass is strong enough for a lapping surface on a steel barrel? Or do you plan on it wearing in to fit the barrel?

 

[Brad]

Brass is softer than steel and holds abrasive well for lapping a crown.

 

[Gary]

What Brad said.

 

[mattw]

Ah, thanks for indulging my lack of knowledge. Have never touched a crown, have always had it done. I have an old 22 that has a dink in the crown and is not worth a gunsmiths time, but maybe my time.

 

[Brad]

With abrasives the old adage is that softer cuts harder. Softer material allows the abrasive to embed in it and this is what does the lapping. Same reason we fire lap with soft lead bullets.

 

[mattw]

What kind of compound do you use? One of the Clovers in grease?

 

[Brad]

Yep. Silicon carbide by choice. Maybe 400-800 grit for a final polish. Need coarser if doing more cutting.

 

[mattw]

Darn, I just keep coming up with reasons to use the lathe that I don't own and wish I did!

 

[Brad]

I did that right up until I owned the lathe I wanted. Now this a mill, should be here next month.

 

[Kevin Stenberg]

A question from a non metal worker. Without a pilot to hold reamer square how can you true the crown.
Unless the barrel and polisher are held in a lathe?

 

[Brad]

Big difference between a crown and a crown!
Doing what Bill did is refacing the entire muzzle square to the bore.
When we polish the crown we mean removing the little burr thrown up where the bore meets the crown. This lapping is minimal, it only removes enough metal to clean up the burr and possibly a little more.

Using a round bottomed lap in a drill with abrasive works well. You move the drill in random arcs to keeps the abrasive fresh and prevent the lap from cutting off kilter.

You could even use a marble and abrasive if needed. Just roll the marble with the palm of your hand.

 

[porthos]

it makes me fell better if i push a tight fitting patch to about 1/2 inch from the muzzle. after lapping i clean up with q-tips, then push the patch out thru the muzzle, followed by a few more.