Eleven degree muzzle crown

[Backwoods]

Okay, I'm in the process of rebarreling a pair of Pedersoli rolling blocks which are to have 11 degree target crowns. The 11 degree part isn't a problem but I am unsure about the treatment of the edge of the bore and crown. Do I leave the edge "sharp" so to speak or do I break the edge with a crowning ball like a normal crown? The sharp edge looks easily damaged but the use of the crowning ball would seem to be counter-productive. Any input here would be much appreciated.

Don in Ohio

 

[Badger Arms]

This is theory more than reality, but I'll bite. The 11 degree recessed crown is meant to prevent damage to the crown. They call it a 'target' crown because the rifle is accurate enough that damage to the crown will degrade accuracy. It's the consistancy of the crown that's more important than the shape of it. The recessing ensures this consistancy.

Me, I'd break the edge for the reason you said. On an accurate rifle, MAKE SURE YOU PROTECT THE CROWN at all costs. Being anal-retentive about this is a good thing.

 

[Traveler]

I used to do a lot of crowning/recrowning. For a while I was wondering what the manufacturers were doing, I saw so many poorly crowned barrels.

I cut the new crown out from the center to minimize any flash. I also hone the newly cut crown with compound at the actual bore. With an 11 degree cut I always leave a small flat area of 1/16" (or so) on the muzzle face, and break the outside edge slightly. I like the look of such a crown, although if the bore is not perfectly centered (which can and does happen) it becomes pretty obvious.

 

[mete]

The 11 degree was supposed to be the most accurate. But absolute necessity is to have the crown perpendicular to the bore and no burrs. Recessing in one way or another protects the crown. A clean edge is important but doing the 11degrees then crowning with a ball makes no sense.

 

[mete]

The 11 degree was supposed to be the most accurate. But absolute necessity is to have the crown perpendicular to the bore and no burrs. Recessing in one way or another protects the crown. A clean edge is important but doing the 11degrees then crowning with a ball makes no sense.

 

[Backwoods]

Thanks for the input. I was pretty careful to do all I could to ensure the crowns were centered. My lathe only has 3/4 inch bore thru the headstock so I had to clamp an aluminum sleeve flush with the muzzle and turn it concentric while the bore was on the dead center. I then cut the crown while the bushing rode in the steady rest.

I actually don't have much concern about my rifle, I can get very picky about how it gets cleaned and cared for. The problem is the other one that belongs to my shooting partner. Now he can get a "little" ham-handed, particularly if things aren't going smoothly. The fact that it's difficult to clean a rolling block from any place but the muzzle doesn't help either. I quess I'll have deliver a stern lecture about what should done and what shouldn't.

Thanks again

Don in Ohio

 

[Traveler]

There is a lot of merit to polishing after making any cut at the muzzle (or anywhere else for that matter). You can cut a new crown just by polishing, but it would take on heck of a long time. However any cut can be smoothed no matter how fine the finish.

For a good explaination of the process refer to McPhearson's "Accurizing the Factory Rifle".

 

[Jim Watson]

If they are to be shot with black powder, dead flat and polished bright is best and authentic. Square bullet exit and easy to clean; any style of recessed crown is harder to get the lube star and fouling off of. Just bevel the corners so the muzzle doesn't cut the gun case. My 1900 Highwall is like that and has a very slight "brass ball" crown to deburr the corners of the rifling at the muzzle. You just don't knock the barrel into hard objects.