DIY cut and crown

greyling22 · Jun 17, 2014

I have a spare 10/22 barrel I want to try a cut and crown on because hey why not, it will keep me out of trouble and a rusty 10/22 barrel is worth $0 if I mess up.

So if I cut with a hacksaw, square with a file, all I need to figure out is crown.

There is the ever popular brass carriage bolt and valve grinding compound, and then I see guys who use the lee case trimmer with an appropriately sized pilot.

I can't find a brass carriage bolt, would any smooth head bolt work? (zinc plated steel)

or if I use the lee trimmer, could I get by with a .223 pilot? and would I still need to use the valve compound and bolt to get the last little bit right by the rifling?

attached are example pictures of the lee trimmer on a barrel

greyling22 · Jun 17, 2014

http://forums.gunboards.com/showthread.php?70890-Lee-Brass-trimmer-for-crowning-muzzle

dsm · Jun 17, 2014

PTG makes piloted crowing tools for the DIYer that does not have a lathe. Of course, a lathe, high RPM and a sharp bit is the best.

BBBBill · Jun 17, 2014

The carriage bolt and lapping compound really only polish the crown and remove micro burrs after the crown is cut. So case trimmer, lathe, or purpose made hand tooling to get the shape/angle that you prefer. You can get a brass bolt at any store with plumbing supplies. They are used to attach toilet tanks to the bowl.

greyling22 · Jun 17, 2014

aha. plumbing store. I was aced out at home depot and lowes in the hardware department.

dsm, I'm sure that the ptg too is super awesome and all that, but I'm just playing around. and broke. I need to contain costs. the fewer the dollars the better.

BBBBill · Jun 17, 2014

Home Depot and Lowes will both have them in their plumbing dept. Heck, you might already have one lying around from your last plumbing repair.

greyling22 · Jun 17, 2014

BBBBill said:
Home Depot and Lowes will both have them in their plumbing dept. Heck, you might already have one lying around from your last plumbing repair.

not in my stuff. the 1 time I had to remove a tank it was just to replace the seal and I reused the bolts.

do you think the 223 pilot covered in grease would work without messing up the rifling? then follow it up with the bolt/grinding compound?

25cschaefer · Jun 18, 2014

I have found, through experimentation at gunsmithing school, it is extremely important to have an exact fitting pilot on a hand crowning tool. If it has anything over .0002 (two ten-thousandths) "slop" you run a very high risk of chatter that is a pita to get out without a lathe. I noticed in one of those pictures that somebody is shimming the pilot, once again, not recommended as the pilot can tip or be pushed off center, depending on the shim. The whole point of crowning is to have the muzzle square to bore line, using loose pilots or shims is defeating the purpose.

For the brass bolt hing to work, the crown needs to be damn near perfect to start, you need to take you time with the file and finish with a very fine file in order to achieve the desired result. Also, don't over do the polishing, you should clean it up just to the grooves, then stop.

Either way you use, make sure you clean the chips and or lapping compound out of the bore before firing.

Sunray · Jun 18, 2014

You ever file anything flat and square by hand? Easy it ain't. Very much doubt a case trimmer, that's designed to cut brass, will be hard enough to cut steel. Never tried it though.
Brownell's sells crowning tools for not a huge, ugly, pile of money. Using the right tool will save you tons of grief.

morcey2 · Jun 18, 2014

I've used the Lee-case-trimmer-and-a-brass-bolt method of recrowning a couple of barrels with great success. Granted, both of them were rebarrel-candidates and it was a last-ditch effort to salvage the barrel. One of them was a sporterized Spanish large-ring mauser that went from over 3" groups at 100 yards to under 1" with a new crown. It may still get rebarreled, but that's now quite a ways in the future.

The lee trimmer is definitely hard enough to cut the barrels I've used it on and continue to easily trim brass afterwards. I wouldn't do it on a new barrel, but it's definitely worth a try as the last attempt before scrapping a barrel.

Matt

greyling22 · Jun 18, 2014

Sunray said:
You ever file anything flat and square by hand? Easy it ain't. Very much doubt a case trimmer, that's designed to cut brass, will be hard enough to cut steel. Never tried it though.
Brownell's sells crowning tools for not a huge, ugly, pile of money. Using the right tool will save you tons of grief.

exactly on the file. That's why I thought the lee trimmer might be in order. It should cut a fairly square crown where it matters, then I can get pretty close with a file or belt sander or something. Remember, this is a cheap throw away project for a 10/22 that will eat bulk ammo only. It doesn't have to be great.

rcmodel · Jun 18, 2014

I have crowned a lot of rifes years ago with a hacksaw, machinests square, a file, and a brass round head bolt in a drill with auto valve gringing compound.

You can grind the inside crown as deep as you want it.
It just takes a while.

The only trick is, the muzzle has to be filed as square as you can get it.

And you have to keep rotating the drill round & round & side to side as it spins to keep it cutting evenly on all sides of the bore.

If you don't the round head brass bolt will get a groove worn in it and all bets are off as to whether the crown will be round or not.

If the bolt head wears evenly round, you can be assured the crown will be ground perfectly round too.

rc

25cschaefer · Jun 19, 2014

Filing flat and square is an art, bench metal was the most frustrating classes in gunsmithing school, it takes a lot of practice. I can comfortably file a barrel flat and square to under 0.002" I have proved that with a pistol barrel that went to the surface grinder after I squared it. It is not my favorite thing but it can be done.

The hand crowning kit that comes from Brownell's has very undersized, general, pilots. It cuts fine on some barrels but chatters excessively on others, without a tight pilot, particularly on stainless barrels. My class ended up making a bunch of pilots to fit most common barrels, this turns a mediocre tool into a usable one.

greyling22 · Jun 19, 2014

well this is as far as I go tonight. Wrapped a bit of masking tape at the cut line and used a small T square to get it pretty square, then cut the barrel with a hack saw, then squared it up as best I could with a belt sander. (first 2 pics) Then I got out the lee trimmer and cut a small recessed area, which really helped with the squaring process. Then I deburred it a bit with some 300 grit sandpaper. (the next 2 pics) There are definitely still chatter marks on the muzzle, but I think that when I paint it matte black with the bbq grill paint it will tone them down.

I have the brass screw and the valve compound ready to go, just no more time today. (Remember, this is not a target rifle, this is not a money consuming project, there will be no sending off for cerakote or worrying about super tight groupings. This is bubba gunsmithing at his finest)

as an aside: if I was to drift out the rear sight and fill it with something, would jbweld or bondo be a better option? and would it work or be worth to fill in the warning on the barrel if I use bondo?

rcmodel · Jun 19, 2014

I would use bondo.

I don't have good luck with JB Weld setting up as Hard as it should in a reasonable length of time sometimes.

Don't know about filling the warnings.
They would have to be draw filed to get all the raised lettering off and keep them from showing through the paint.
Then there might not be much left it fill so it would stay put.

Hard to say though, without seeing it.

rc

greyling22 · Jun 19, 2014

enh, I won't push my luck. I'll just bondo the sight notch and leave the rest alone. I've had issues with things showing through paint before.

ldlfh7 · Jun 26, 2014

The picture of the old Mauser you put in your post was my 1st crown project.
Definitely not the best method out but it worked for me.
Rifle went from shooting minute of barn to 3-4 inch groups at 100 yards with iron sights.

Centurian22 · Jun 26, 2014

Very nice job! Was there a need or point beyond trying your hand at the process? Not that there needs to be. Just didn't know if the gun wasn't shooting well or you wanted something shorter to fill a different purpose.

docsleepy · Jun 26, 2014

I've crowned two or three Mosin-Nagant's using the case trimmers. The results generally shot about 1 1/4 inch groups at hundred yards using a scope. I think it's important to get a nice square crown. If you will carefully pick the case trimmer pilot size to be just smaller than your bore, and then shim them with plastic, I used McDonald's straws cut appropriately, you can end up with a relatively tight fitting and one and a half inch long pilot that will keep you nice and square.

I use the round brass bolt and lapping compound with great outcomes.

docsleepy · Jun 26, 2014

Two of my rifles I subsequently was able to hit an 800 yard AR 500 target with. That is adequate accuracy for me for hunting purposes.

docsleepy · Jun 26, 2014

Your photos look pretty good. If you work at it with the shims and by hand, you should be able to get the chatter out. However I once saw an article where they took a fine hunting rifle shot test groups, and proceeded to ding the living daylights out of the crown in every way imaginable, shooting groups as they did more and more damage. There was almost no change to the groups, and some cases they got better. The conclusion I drew was that the radius applied by the brass screw was probably the most important portion.

greyling22 · Jun 26, 2014

Centurian22 said:
Very nice job! Was there a need or point beyond trying your hand at the process? Not that there needs to be. Just didn't know if the gun wasn't shooting well or you wanted something shorter to fill a different purpose.

The scope I put on the rifle had a wider field of view than the previous scope, and the barrel showed up in it at low powers. I thought wacking off some of it would help. It did, some. But mostly I had a takeoff barrel, and had a little time, I thought I would try.

DIY cut and crown

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