Crowning a barrel

[peter nap]

I don't have a lathe anymore and need to crown a 30/06 barrel.

Sad, but I never did it without a lathe and I really don't want to buy one of those Brownells crowning bits for one gun.

I've read about using a carrige bolt and lapping compound. Anyone ever do this and any other suggestions?

BTW, this isn't a match grade barrel. It's on a 1917 Enfield that someone has done a very BAD job sportizering.

[Doughty]

I think you'll be okay with any round headed screw/bolt as long as it's brass and big enough. I used one with the straight slot in it and a hand drill. It sure improved the crown that I was working on. Make sure you have got light and magnifers so you can see good what you're doing.

Richard

[docone31]

Get a 1" coarse grit ball. Chuck it in a drill. Drill away.
Get a Carriage bolt that will fit the contour of the ball. Use lapping compound.
With both the grit ball, and the carriage bolt, move the drill around equally. This should give you an acceptable muzzle.
http://www272.pair.com/stevewag/muzzle/mz.html
This was a site That helped me do it.

[rob45]

IF the crown was originally made concentric and square (perpendicular) to the bore, then a MINOR repair can be done by lapping. Various implements can be used, but they all work on the concept of using a lapping/grinding compound to grind/polish the crown.

The oldest (and most economical) method is to use a glass marble or steel bearing. Simply apply compound to the marble. Place on the crown, apply moderate downward hand pressure while rolling the marble.

Another lapping tool is a brass muzzle lap. This tool is nothing more than a stud with a half-spherical end that you chuck into a drill and use the same way that you would a marble/bearing, only now you are using a drill to rotate it instead of the palm of your hand. These cost about $20 (maybe? Been a while since I bought one) and are definitely quicker than doing it by hand.
The use of a carriage bolt is the "poor boy's" alternative to using a brass muzzle lap.
Some report good results with it, but I have mixed feelings about using a bolt, and here's why:
A bolt is not necessarily finished to the same degree of perfection as what is needed to finish a crown. The head of the bolt needs to be perfectly spherical to accomplish the results you want.
With that said, please realize that those statements are based only upon my experience, and others have reported successful results using a carriage bolt. Always keep in mind that everyone's mileage varies.[smilie=l:

Unfortunately, you report that someone did a poor job of sporterizing your rifle. If the barrel was cut and recrowned, and they did not crown square to the bore in the first place, then no amount of lapping will fix it; you will have to cut a new crown. The crown must be square to the bore for any type of acceptable accuracy.

I use lapping to fix minor damage/blemishes. These are instances where the original crown was already square to the bore. Think factory guns that are likely to have been cleaned from the muzzle (muzzleloaders, certain lever actions, etc.).

If I am cutting a barrel to a shorter length, then obviously a new crown has to be cut using one of the piloted tools as sold by Brownells, as that is the only way to ensure squareness. If your crown is not square and you do not wish to invest in one of the crown cutting tools, then most gunsmiths usually charge $25-35 for that service.

Hope this helps.
Good Luck.

[JIMinPHX]

I used to use tool maker's balls in a hand drill with clover paste. Then I heard about other people having good luck with a round head brass screw & valve grinding compound from the auto parts store. Tool maker's balls are kind of expensive.

[docone31]

If, it ain't square, that technique won't work. I have used it to clean up a muzzle that had cleaning wear on the muzzle. I did not do it to any barrels that weren't square to begin with.
A lathe does a great job of clean up.

[Mk42gunner]

I have done several crowns on cut down milsurps with a conical stone in an electric drill. Like any other job, pay attention to detail.

This might not be the best way, but it has worked for me in the past. Get a new stone, (the last one I bought was a dollar at the auto parts store), and dress it once it is in the drill. I grind just enough of the rifling away to get to the bottom of the grooves evenly, and call it good.

My .35 Whelen has put three rounds under a quarter at 100 yards with this type of crown.


Robert

[David2011]

. . . just thinking "out loud" here, but what about adapting a faucet grinding tool to square up a crown? The cutters are inexpensive but I would expect that they're true enough to cut a crown accurately. Seems like a mandrel covered in a layer or two of heat shrink tubing and threaded to accept the faucet cutter would be as good as a Brownell's tool for one off work. If the mandrel was made from a piece of tubing with internal threads the cutter could be attached by a socket head capscrew or headless bolt. It could be turned with an allen wrench or battery powered drill. The dimensions should work well for a piece of 1/4" steel tubing covered in heat shrink for a .30 cal barrel. Is it worth considering?

David

[nicholst55]

I believe you can rent those crowning tools from one of the reamer rental places.

[KCSO]

I have had to recrown barrels in the field and have done an acceptable job with a tool makers square and a file and a brass bolt. File the barrel flat and as square as you can by hand and then lap in with a brass bolt loaded with grit. I use a valve seating drill that wig wags but a regular drill will do. If you work carefull you can get a crown that will let you hold into an inch and a half at 100 yards.

[pietro]

I've used brass round-head screws and valve grinding compound to crown muzzles successfully since the mid-70's.

I buy several new round-head brass screws in several different sized heads that go from a size that just barely won't enter the bore/rifling, to a few gradually larger sizes.

I buy a can containing both fine/coarse valve grinding compound at an automotive supply store.

Although YMMV, I start with the small screw head and coarse grit, working the hand drill around the clock at angles as it cuts, moving on th the next larger size screw head once I see a smoothed/ground band around the rifling/crown.

I then repeat with the fine compound and a new set of screw heads, after first cleaning out all the coarse grit from the barrel (from the chamber end)

The result can be polished with emery cloth and/or cold blued.

.

[doctorxring]

.


John Zhu at Accumounts carries a very useful and inexpensive
muzzle crown cutter kit with 10 pilots. $159 well spent. I've used it
many times to clean up crowns on various rifles. The 45 degree cutter
is the most useful. Very easy to use. About a 1 minute job.

http://www.accumounts.com/


.

[Storydude]

Lee case trimmer+case length gauge that fits barrel+vicegrips locked on cutter+about 100 turns=nice target recessed 90* crown.

[rob45]

Lee case trimmer+case length gauge that fits barrel+vicegrips locked on cutter+about 100 turns=nice target recessed 90* crown.

Sounds like a good idea; providing the gage is turned down for proper fit within the bore, it would make a very economical pilot.

100 turns?!?!
Wow! Is any part of your name Job? :kidding:
Thanks for the idea.

[Mallard57]

http://www.youtube.com/user/MidwayUSA&rclk=cti#p/search/1/OorpZlG28fI

[Storydude]

Sounds like a good idea; providing the gage is turned down for proper fit within the bore, it would make a very economical pilot.

100 turns?!?!
Wow! Is any part of your name Job? :kidding:
Thanks for the idea.

Probably could do it with less, with more pressure.

I was amazed at how well it cut a muzzle with it.

[dragonrider]

This is the one I made years ago. It is only an interchangable pilot conterbore, happens to be a 19/32 diameter because that is what I had around that I used the least. Resharpened to 45 degrees and I make whatever pilot I need at the time. Pilot pictured is for 22 cal. Inexpensive and pilots are simple and easy to make.
http://img.photobucket.com/albums/0603/PaulGauthier/BARREL%20CROWNING%20TOOL/IMG_0281.jpg

Simple to use, place in the bore and half a dozen turns or less and you are done.