Barrel Crowning

[nighthunter]

I have a Savage model 12 in .223 that has developed a bur around the muzzle of the barrel. This bur is enough to snag a finger nail. I'm pretty sure that a bur like this can and will effect the accuracy of the rifle. How can I remove this bur without ruining the barrel?
Nighthunter

[Bass Ackward]

I have a Savage model 12 in .223 that has developed a bur around the muzzle of the barrel. This bur is enough to snag a finger nail. I'm pretty sure that a bur like this can and will effect the accuracy of the rifle. How can I remove this bur without ruining the barrel?
Nighthunter


Is this a trick question?

Do you mean how can you remove the burr wnd do it with some form of precision? Because I can think of quite a few ways that I wouldn't attempt it on one of my rifles.

[waksupi]

Nighthunter, go over to the Accurate Reloading forum, under the Gunsmith topic. There is a sticky there on barrel crowns. Not necessarily a fix, but more about the effect of bad crowns.
Shoot the firearm, and see if it is indeed throwing shots. Actually, if burred, the group would probably be pretty much the same, just landing in a different place than originally sighted for.
I've done some fairly crude jobs on milsurps in the past, with no problem. If a real serious nick, a little work with a needle file to smooth it out. Then, some emery paper spun with a round head bolt in a drill.

[Char-Gar]

If the burr is hnot hanging into the bore if probably won't make much of a difference. just remove it. If it is hanging into the bore a couple of shots might take it off.

If you need to remove it and it is hanging into the bore. Brownells sell a neat little brass 45 degree lap you can put in an electric or hand drill. A little emery compound and you are in business.

First thing to do is shoot it and see if you have a problem after a few rounds.

[versifier]

Brownells also sells piloted recrowning cutters "Muzzle & Cylinder Facing & Chamfering Tools" with 90* facing cutter and 45* chamfering cutter. It comes with one brass or steel pilot and you can get separate brass or steel pilots for it in a bunch of other sizes. Just got one for xmas - haven't used it yet, but plan to for damaged and/or bubba'ed .30 and 8mm milsurps. If the sensible advice provided above by other members does not fix the problem, one of these will do it quickly and easily, but should not be necessary under normal circumstances. I've got a pair that have been absolutely trashed and need major surgery.

[kywoodwrkr]

The gunsmith books I have suggest using a round head brass screw with fine valve grinding compund on it used in a cordless drill at very slow speed.
Obtain this at a NAPA type store.
I'd burnish first clockwise and then reverse and burnish counterclockwise.
Moving the outboard end of the drill in a small circular motion insures a fairly good balancing of the actual burnishing.
Use some common sense in determining how large a head the screw should have.
FWIW
DaveP kywoodwrkr

[nighthunter]

Kywoodwkr, Versifier and Charger .... Thanks for your posts. This rifle is one that I use for benchest competition at the local club. I'm sure the bur has some effect on accuracy as it extends the entire way around the muzzle. I honestly believe it was not crowned correctly at the factory. I'm going to try the brass screw with lapping compound. I'll let you know how I make out.
I don't honestly know how BA came to think this was a trick question.
Nighthunter

[KCSO]

Take a brass shut off ball from an old lever style water faucer or buy a new replacemtn at the hardware store. Charge the ball with emery say 220 and cuuck it in a drill and alpply it to the muzzle while twisting the drill in a circular motion. Do this forward and reverse and than go to 400 grit. This will take off all the burrs and as you are twisting a ball that is turining in the drill it will self center to the bore. Presto perfect finish to the crown, no burrs. If you can't get a shut off do the same thing with a brass 3/8 or bigger round headed cap screw.

You want the ball or bolt just big enought to contact the edges of the bore.

[Bass Ackward]

I don't honestly know how BA came to think this was a trick question.
Nighthunter


NH,

Because on a rifle like that, .... there is one only one way to do the job properly. And that is to indicate it up and do it in a lathe.

The goal .... is not .... to remove the burr. You can do that with a pocket knife. The goal is to find out why it formed and then cut the crown with the bore if everything is OK. It may even require that the end of the barrel be faced to maintain integrity of the crown.

It probably WAS done right at the factory on this quality of rifle. That's what has me concerned. So if it formed, then there is something not right. You may even need to shorten that barrel slightly to prevent it's return. Who knows without seeing.

You have Schrekengross (sp?) up there close by you. Probably $40. Good guy.

[monadnock#5]

Reid Coffield the gunsmith did a series on converting a Mauser to custom sporting configuration in a series published in Shotgun News awhile back. For crowning the barrel he used a slotted brass screw with valve grindind compound chucked in a hand drill, the old fashioned eggbeater style. His technique was to work the drill handle in figure eights while spinning the screw. If you were to use a power tool, in line with the bore, I suspect you would end up with pretty much with what you have now.

[mozark]

While I agree with B. A. that work on a crown ought to be done on the lathe, I've found that sometimes it's not practicable. I would caution against using a power drill. it's just too easy to drift the crown off-center. To touch up a crown that is otherwise symetrical find a brass ball (available from MSC and the like) that is the right diameter to work the area of the crown in question, charge it with 220 lapping compound, and work it with the thumb and first two fingers. This method can take awhile but won't run off-center.

MM

[Char-Gar]

Nighthunter... I didn't know this was a benchrest rifle you used to compete. That is a whole new ball game.

For ultimate accuracy the crown must be perfectly even and 90 degrees to the bore. When a bullet escapes the muzzle, the gases will give an uneven shove to the bullet base if the crown in not perfect in all regards.

I have recrowned barrels using the Brownells hand tools and the brass screw. These work well for hunting rifles and others not used for competition.

Bass is 100% correct, for ultimate accuracy the barrel must be recrowned by somebody with proper machinery and skills. Factory crowns are often less than perfect and rifles will often give better accuracy when the barrels are recrowned by somebody who knows how to do it right.

There is no sense in trying to compete with a rifle who's crown is less than perfect.

[felix]

Savage does not make BR guns to my knowledge. Remington did when Mike Walker was there, but I don't think anymore. A gun used for BR is not necessairly a BR gun which exhibits an action the size of a tank. ... felix

[Willbird]

Uglier than the tank TOO Felix, and run in a wheelabrator for quite some time too :-).

many BR shooters are rumored to have a bbl re-crowned before any major shoot.....I would just send the bbl to a well known smith for a crown job.

I bought a 700 action from Paul Dorsey, he sent me a 308 barrel with it that along with the action belonged to Virgil King the Houston Warehouse guy.........the crown on that barrel is just a think of beauty........it is polished as bright as a mirros and perfectly flawless.........it humbled me to try to do as nice when I do one for myself :-)

Bill

[mainiac]

Ive shot real benchrest rifles for years. Have spent the money to have guns that are as good as human hands can make. There was a feller that used to build his own guns(he has since died), it was a day of good conditions,and most of us was shooting high x scores and he was really lagging. He came up to a friend of mine that was loading beside me,and saw a rcbs case deburring tool in his box,and asked to borrow it. He put his rifle on the bench, and run this deburring tool into the muzzle! I actually see chips falling out of it! After a few more cranks, he said there" I new I frigged up that recrowning job the other day!" On his next relay, he shot a 50 with 5 down-town X,s and told me that was what was wrong with his gun! I just shook my head in wonderment! It makes a man wonder sometimes!!!!

[Bass Ackward]

Well, there is so much to crown. This is just as important as the base of the bullet because they work together.

And crown to me is just not the break, it's the barrel diameter and condition before the break and the barrel face also if you like tappered crowns. The cut can be perfect with the bore, but if gas starts leaking around the bullet before it hits the 90 degree break, you have nothing because the crown will be established back in the bore.

Then when you have tapered sides that aren't true, even if gas breaks perfectly, the part that is closer to the barrel is going to exert more force than the other side, thus ruining what you have. So there are three factors that affect crown.

The shorter the barrel, the higher the pressure at bullet exit, the more important the crown. The more over bore the case, the higher the muzzle pressure and the faster it eats the barrel away. Some calibers like 7MM STW, you can see improvement at 200 rounds if you cut back 1/8" and recrown. But mine are always checked and especially after fire lapping. 90% of the time, it must be done to be 99% true.

Is it important for everyone to be that fenatical? No, but I am going to tell you the right way (as I know it) and you take it from there.

[KCSO]

Yes you can, after a lot of practice, crown a muzzle by hand and do a good job. As Bass said the higher the pressure the more important it is that the crown be right. I learned to crown MUZZLELOADERS with a square and a file and an old brass bolt in a wig wag drill. I do all mine now on a lathe with sharp cutters and lap them in to 1000 grit. Those old muzzleloaders would shoot into 3" with iron sights at 100 yards, I just delivered a .54 hawken that shot an honest 5 shot group at 100 yards of 1 1/2" c-c. Did the lathe and special tools help, I think so. If you want the bullet to go straight make the base of the bullet and the crown of the barrel as square as is humanly possible and you can't go wrong. If you plan to shoot into 4" at 100 yards, it doesn't make a whole lot of difference how you do it. Bass said how it SHOULD be done, each person has to decide for himself and go from there. I personally wouldn't shoot any gun with a burr on the muzzle, and I keep a protector on the muzzles of my good rifles when they are off the rack.

[uscra112]

Is this really a burr of metal, or is it a buildup of powder residue?