muzzle crowning

[Hatman/2nd line]

Does anyone have any info on crowning a barrel?

 

[Cruzatte]

Do you mean coning? To the best of my knowledge, muzzle loading rifle barrels come crowned from the maker.

 

[rich pierce]

The crown or edge transition from the face of the muzzle to the bore is critical to accuracy. If at all sharp then the sharp edges will cut the patch with tight patch/ ball combinations and good accuracy cannot be obtained. Some think a simple countersink will suffice but many times it will not. The part that matters is the last transition to the bore. Getting that edge rounded allows loading of tight combinations without cutting patches at the muzzle. I’ve seen guys lap barrels and try every ball/patch/lube combo and not fix patch cutting till they fixed the crown.
one way depending on caliber is to use finger or thumb and press 320 grit wet or dry sandpaper into the muzzle. Rotate right and left, turn the barrel 90 degrees, repeat with new paper, go around the barrel 4 or 5 times. Get your readers or magnifying glass out and inspect that edge. Alter your technique until it’s nice and smooth, very slightly rounded. All this within 1/8” of muzzle. Almost no metal removed.

 

[pooch156]

If memory serves me correctly the tools necessary for proper crowning of a barrel are quite expensive. I leave that up to the trained gunsmiths as it must be done properly.

 

[Artificer]

The crown or edge transition from the face of the muzzle to the bore is critical to accuracy. If at all sharp then the sharp edges will cut the patch with tight patch/ ball combinations and good accuracy cannot be obtained. Some think a simple countersink will suffice but many times it will not. The part that matters is the last transition to the bore. Getting that edge rounded allows loading of tight combinations without cutting patches at the muzzle. I’ve seen guys lap barrels and try every ball/patch/lube combo and not fix patch cutting till they fixed the crown.
one way depending on caliber is to use finger or thumb and press 320 grit wet or dry sandpaper into the muzzle. Rotate right and left, turn the barrel 90 degrees, repeat with new paper, go around the barrel 4 or 5 times. Get your readers or magnifying glass out and inspect that edge. Alter your technique until it’s nice and smooth, very slightly rounded. All this within 1/8” of muzzle. Almost no metal removed.

Great illustration, Rich,

Gus

 

[Kansas Kid]

It doesn’t really matter as long as it even all the way around the muzzle is square and don’t cut patches .

 

[andy52]

Brownells has hand crowning cutters up to .50 cal for Muzzleloaders the cost of the tools to face and crown a barrel is about 150 bucks.

 

[SDSmlf]

I take the ‘thumb and sandpaper’ on bore crowns a little further, just for the sake of consistency, at least in my opinion.

I use a series of ball bearings, from about one and half times the bore diameter, to right around bore diameter, and use sandpaper of different grits from 120/180 up to 320 or finer (I take it up to 1000 grit for a mirror finish). A couple of turns of muzzle over each ball bearing with progressively finer sandpaper over them gives a smooth barrel crown to bore transition

Basic idea is to hold the sandpaper over the ball bearing (you can place ball on the floor and hold paper with your feet, maybe on a pad or thin carpet if you don’t have a lathe to chuck up the barrel in) and rotate the barrel bore on the bearing with the paper on it. Easy to keep barrel square with the floor. I’ll start with the larger diameter bearing and roughest grit paper and end with a smaller ball bearing near bore diameter, repeating with progressively finer grit sandpaper. I stop when I have a slight chamfer on bore and rifling lands that is highly polished.

I use Dykem (or a Sharpie) to mark the inside the bore so I can easily see when I starting to clean up everything without going too far. Note the 60° chamfer in the photograph was cut on a lathe, I just use the ball bearings to break sharpe edges and polish.

Just note with either method. If your barrel is already finished, you are going to remove finish from the face of the bore if you don’t protect it. I’ve used ‘masking’ tape with a hole punched through it (use a wad punch), but only on other people’s gun’s, not worrying about it on mine.

 

[rich pierce]

That’s a shooter right there.

 

[oldwood]

I'm with Rich. 320 emery cloth w/thumb, maybe a little 400 grit w/thumb for cleanup. A tool can be made out of a 2 " paper clip to check for burs at the muzzle. Straighten one wire segment of the clip and bend a 1/8 " right angle in the wire . A burr can be in a groove or on a land and is easily detected by the paper clip tool. Just slowly drag the clip out of the muzzle on each land and groove. A good crown has no burrs. .........oldwood

 

[Tb54]

Just a variation of SDSmlf’s bearing idea...

years ago I read an article about Recrowning, in a gun magazine, useing the same procedure but with valve grinding compound

 

[pmccoywss]

I used the steel ball and valve grinding method when I built my rifle in 1976. Make sure the barrel is cut square to the bore. I used an old leather glove and rolled the steel ball with grinding compound with the palm of my hand while watching tv. Worked fine.

 

[csaduck]

I used a Dremel tool and fine sandpaper with a ball bearing to get this right.

 

[user 34300]

The best way to crown a muzzle is with a lathe. Piloted cutters are OK, assuming the pilot fits your particular barrel. These cutters and pilots are expensive. Everything else is a matter of luck as to whether the rifle will shoot accurately and where the bore is pointed.

 

[Vaino]

I use a suitably sized ball bearing w/ fine valve grinding compound....the ball bearing has 2 flats ground on for clamping a small Vise Grips. ....much easier to rotate the ball bearing

To ensure that the face of the muzzle is square to the bore, a "V" block is clamped on a straight bbl w/ a small height of the muzzle above the "V" block surface. It's then filed level w/ the "V" block surface and lightly stoned.

For a swamped bbl, shims are paced on both angled surfaces at the "V" block end opposite the muzzle end and the shim thickness is determined w/ a simple trig calculation.....Fred

 

[Zonie]

I form the crown on the barrels I've shortened by using a conical grinding wheel. The kind made to be used in an electric drill. The wheel with a 45° angle works well but one with a 60° included angle would also work.

I DO NOT use a electric drill to do this job. Instead, by inserting the conical grinding wheel into the muzzle and holding the drive shank in line with the bore, I use my fingers to rotate the wheel back and forth while rotating the barrel with my free hand.
I stop the grinding just after the size of the cone reaches or has passed slightly deeper than the rifling grooves.

I follow this up by using my thumb and a 1" X 1" piece of wet/dry silicone carbide sandpaper, again, rotating it back and forth as I rotate the barrel slowly.
This removes all of the sharp edges that can cut a cloth patch and leaves a nice, smooth, rounded edge which finishes the job.

 

[Professor flintlock]

I use a round carbide burr bit (a good one not chinese) put it in a bit brace .Place it over the end of a square barrel using light pressure and a swiveling motion cut your crown when it looks good quit.Not real difficult. It works quite well . Few guys outshoot me and I've done many rifles and pistols this way

 

[hanshi]

I crown all my rifles by starting out with a sandpaper wrapped "plumb bob". Because of the long, tapered shape it works for any caliber. And as zonie mentioned a finger rotated conical grinding bit from a Dremel tool set is also used. But the final polish usually comes from sandpaper and thumb - with 0000 steel wool used for the final polish.

 

[Eric Krewson]

I use the thumb method with sandpaper, I have done two so far with excellent accuracy as the results. Just did a GM drop-in for a TC but haven't shot it yet to test my work, The crown was cutting patches all the way around as the barrel came from the factory.