How Hard is it to Crown Your Own Barrel?

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Ranger30-06

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Pardon me if this is a really stupid question, but I have been thinking about this for a while.


My question is: How hard is it to crown a barrel yourself? I mean like take a Dremel and a pointed grinding bit, stick it in the end of the barrel as straight as possible, smooth it out with a polishing bit, then clean up the barrel with a normal cleaning brush. Isn't that all gunsmiths do? Am I missing something?

Thanks.
 
Yep!!
No way you can do it with a Dremel and get even close to a perfect edge, which is the whole purpose of crowning in the first place.

The old gunsmith Tried & True way is:

1. Cut the barrel if necessary.
2. True it up perfectly square with a file and a machinists square.
3. Use a large round head brass screw in a drill with #240 valve grinding compound.
4. Rock and rotate the drill continuously while spinning it and it will lap a perfect crown.

rc
 
That "old gunsmith tried and true way" was never used by any gunsmith I know, and I am a bit surprised to see rcmodel advocating it. A really good crown job needs a good lathe, not a brass bolt which can cut into one side or another with no way to keep it in line with the bore.

If a lathe is not available, there are some crowning tools (Brownells sells them) that can do a good job if used carefully.

Jim
 
No less a gunsmith then Roy McFarland wrote a gunsmith book published in 1965.

In it, he writes about using a brass screw lap to cut a perfect crown, and how to do it.

I used the method on the first 03A3 Springfield sporter I built.
It shot 1 MOA then, and it still shoots 1 MOA now.
It worked then, and it will still work now.

A large round-head brass screw used in constant motion in all directions will not cut more on one side, or off center, because it can't.
It is self-centering in the bore, and the constant movement & rotation keeps it from cutting more on one side then the other.

At least it is a heck of a lot better then trying to grind a crown free-hand with a Dremel tool!!
Or even chucking a barrel in a 3-jaw lathe chuck instead of dial indicating it in a 4-jaw to center the bore!

If you don't have a lathe or know how to use one if you did?
You do with what you got.

If you haven't done it, don't knock it!

rc
 
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I redid the crown on my TC Encore .223 rifle because it looks like the tooling that Thompson used to do the crown was badly worn. I didn't try shooting it before the recrown, but after the recrown the barrel shot better than MOA at 100 yards.

I used a method similar to the procedure described by rcmodel which is, by the way, identical to the method recommended by James V. Howe, in his work "The Modern Gunsmith", published originally in 1934.

Howe recommended using "flour emery" and olive oil to create a home-made lapping compound and referred to the entire operation as "lapping the muzzle". He also gave general guidance on picking the specific screw-head diameter for a given muzzle size. What's interesting is that Howe recommended "lapping the muzzle" using the brass screw method even in the case where a gunsmith might have a lathe available.
 
The method described by rcmodel was and is used by traditional gunsmiths without a lathe. It is hard to mess up. Round will seek the center of a cylinder.
 
Oh they work.

But I can't see paying $14.00 bucks for something a $1 brass Round Head screw ot bolt from the hardware store would do as well.

rc
 
I have a .303 British SMLE that needed some crown work. I took it to a gunsmith to be recrowned. He charged me $25.00 and it looked like he took a Dremel tool to it. I could see the grinding marks and the crown was lopsided. I took my case chamfering tool and reworked the crown with it. After about 20 minutes the marks were gone and the crown was even. I haven't shot it since, but I am looking forward to seeing what the improvement might be.
 
Dave Manson makes a a great piloted hand turned crowning tool. Here is a youtube video of him using it: http://www.youtube.com/watch?v=-Xpzv1Spsnk

The only way to get a perfectly square crown is parallel off the bore and this tool does that. I've used this tool and it works great if you don't have a lathe or can't get the action chucked up in the lathe. That said, the price of this tool is high for a one-off job.
 
The Brownell's gun smithing book advocates the brass screw method, so that's a pretty credible recommendation.
 
I'm lucky enough to be able to all my barrels in to work and chuck them up in the lathe and make everything perfect,I usually put a recessed target crown on them. Several of my handguns the before and after groups were quite different,so now it is one of the first things I do when I get a new gun.
 
I have and have read those books. I still wouldn't (and didn't) use a brass screw to cut a crown. I did have the luxury of a lathe with a hollow headstock which makes things a lot easier.

Jim
 
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