Author Topic: useful crowning tool????? (Read 2373 times)

sabbatus · « **on:** March 07, 2011, 02:22:03 PM »

walking around the tool department on the home depot i found a ryobi countersink. package says useful for countersinking, deburring, and chamfering. i think it will work for crowning shorty barrels. i got the 3/4 inch one as it will cover all barrel sizes, it cuts at 82 degrees. all for about $8.00. tried it on a piece of thick wall cold rolled cleaned up the "muzzle" of that pipe nicely. what do you guys think ?

Yak Angler · « **Reply #1 on:** March 07, 2011, 02:37:44 PM »

It looks like it should work to start the crown cutting process, on any barrels i have recrowned i find less aggressive tooling to work the best for the final touch up. That bit looks like it will cut deep and fast into barrel grade steel which will likely leave some burring that will need touched up with a fine grit stone in order to get the polished surface at the end. Only one way to know forsure though so keep us updated on how it works.

sabbatus · « **Reply #2 on:** March 07, 2011, 02:47:39 PM »

i already figure that touch up is necessary, after all that is one area that should be as clean as possible. but getting the initial cut is what i was after

JeffDavis · « **Reply #3 on:** March 07, 2011, 02:49:25 PM »

Did you put it in a drill or did you hand turn it? I would think it would do ok if you found a nutdriver that fit the shank and turned it by hand.

Bill3006 · « **Reply #4 on:** March 07, 2011, 05:32:00 PM »

I think that tool is for countersinking holes for flat-head machine screws. I've used it for such, and the counter sinks are kind of rough. The angle isn't probably the best for a crown either. But if you give it a try, the worst that can happen would be that you need to trim some off the barrel and recrown it with a different method.

sabbatus · « **Reply #5 on:** March 07, 2011, 05:39:28 PM »

turned it by hand, a standard nut driver fits it perfectly. i will give it a good try when i decide to shorten another barrel.

tomf52 · « **Reply #6 on:** March 08, 2011, 01:23:53 AM »

How would you keep it in alignment with the center axis of the barrel? A lean in any direction would be a negative thing.

bikerbeans · « **Reply #7 on:** March 08, 2011, 01:38:55 AM »

If you chop a barrel, maybe practice with the countersink on the cutoff section of barrel and see how it goes?

BB

SHOOTALL · « **Reply #8 on:** March 08, 2011, 02:09:11 AM »

how does the cutting direction line up with the rifeling ? It would seem that if they run in opposing directions they would chatter and do a poor job. Most crown in the 11 degree range to avoid a funnel but there are others, Some use a round head brass machine screw with lapping compound which may be something to consider as if you are not 100% stright with the bore it is not as important with the round head.

gcrank1 · « **Reply #9 on:** March 08, 2011, 03:18:58 AM »

Use it lightly, straight and square and take off the visible land height then just a tiny smidge of the bottom of the groove. I use a head mounted magnifier when doing critical things like this.
Finish dress and it should be fine.
NEVER use power on a tool like that on a muzzle (fools rush in where angels fear to tread).

SHOOTALL · « **Reply #10 on:** March 08, 2011, 03:47:43 AM »

you will know when you go for group !

gendoc · « **Reply #11 on:** March 08, 2011, 12:22:19 PM »

it ain't really hard to crown a chopped barrel. ya jus gotta know what ya need ta do !!!
flat blank crown or recessed ? its up to you !!! get tha right tool for tha select job....
tha finish touch is my favorite

Delkal · « **Reply #12 on:** March 13, 2011, 11:54:06 AM »

The cut will be angled too deep. One of the "magic" crowns is the 11 degree target crown. The cutter is 180-11-11=168 degrees.

You will be better off crowning with a rounded brass nut on a bolt and some grinding compound (search it). I've touched up a number of barrels this way with no disasters, it will give a better angle.

gcrank1 · « **Reply #13 on:** March 13, 2011, 12:02:49 PM »

Short, maybe, a small handful of world-class bench rest shooters I doubt that the vast majority of riflemen will be able to make a meaningful difference in group size with any well done crown, given any reasonable angle.

guns-o-fun · « **Reply #14 on:** March 13, 2011, 12:47:10 PM »

The hardest part of crowning a barrel is getting it cut off square to begin with. If you mess that up, Brownell's has a 90 degree cutter that can straighten things out. Just be careful if you use any power tool other than a lathe. I have started using an old fashion bit brace and with that it's really hard to apply pressure with a bias and get out of square with the bore.

Delkal · « **Reply #15 on:** March 13, 2011, 12:57:29 PM »

I agree. An even crown is 90%+ of the equation. What I like about crowning with a round head brass nut is that it leaves a very shallow, self centering crown. I'm not sure of the exact angle but that is all that is needed (usually). Then go out and shoot it, see if it helps. If it doesn't then you can resort to more drastic cutting. Just go slow!

This countersink could work if you are very careful and keep things level but if it doesn't the only thing left to do is cut the barrel again and start over.

Hit or Miss · « **Reply #16 on:** March 13, 2011, 03:02:56 PM »

I used a brass acorn nut to finish lap the crown on my .223. Now if the weather and my schedule will align I'll be able to put it on paper to see if it helped.

aromakr · « **Reply #17 on:** March 14, 2011, 01:39:08 PM »

I think you are going to find the bit will jump when it contacts the lands and will chatter giving a very ruff finish.
Bob

gcrank1 · « **Reply #18 on:** March 14, 2011, 02:50:22 PM »

The 'trick' is to bring the flutes up to contact on the land(s) and with just a bit of downpressure rotate the cutter (by hand!) to just shave the land(s). As it gets them all down evenly, then only give it that tad of rotation more to chamfer the bottom of the grooves, make yourself stop, and use that acorn nut idea to finish the job. It is easy to try to do this too fast; take your time.
If you could have a muzzle perfectly flat with no crown at all, and no burrs, it would shoot fine. Things being what they are, that chamfer 'ring' around the muzzle must also be straight. square, and even to release the gas pressure evenly from behind the bullet as it exits the muzzle.

gendoc · « **Reply #19 on:** March 14, 2011, 03:00:32 PM »

blake, i bet you cud tell ifin you dug outta bullet from a "specimen" ifin it was from a chopped or factory barrel !!!!

it can be dun... and your very close

bikerbeans · « **Reply #20 on:** March 15, 2011, 01:58:12 AM »

Quote from: gendoc on March 14, 2011, 03:00:32 PM

blake, i bet you cud tell ifin you dug outta bullet from a "specimen" ifin it was from a chopped or factory barrel !!!! it can be dun... and your very close

Doc,

How many legs did that "specimen" have?

BB

ironglow · « **Reply #21 on:** March 15, 2011, 02:09:52 AM »

I wouldn't use it, as others here said, the crown would be too deep and any lean on the tool could leave a mess. Also as some said, the big challenge is to cut or file the barrel squarely.
Larry Potterfield (of Midway) gives good advice; http://www.youtube.com/watch?v=OorpZlG28fI

gcrank1 · « **Reply #22 on:** March 15, 2011, 06:05:44 AM »

FWIW, I have watched a few of his videos; no doubt there is a lot of good info in them, but then I saw him use a powered hand drill for a job that really requires at least a drill press and jigging up.
As Ive mentioned in the past, not unless you are very skilled and/or lucky..........something like that encourages someone to get in way over their head and really mess it up fast, in an expensive way.

McDerry · « **Reply #23 on:** March 15, 2011, 06:52:17 AM »

11 degree target crown is about $35 these days.

gendoc · « **Reply #24 on:** March 15, 2011, 01:09:43 PM »

Quote from: bikerbeans on March 15, 2011, 01:58:12 AM

Quote from: gendoc on March 14, 2011, 03:00:32 PM
blake, i bet you cud tell ifin you dug outta bullet from a "specimen" ifin it was from a chopped or factory barrel !!!! it can be dun... and your very close

Doc,

How many legs did that "specimen" have?

BB

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