Repairing a Barrel Crown

F

Fouranone

Guest
Hello! I have two Ruger barrels, .284" and .338," with roughness, little nicks, at the muzzle end of the barrel (viewed with a 10x magnifier). Is it a good approach to use valve grinding compound on a brass screw in a drill and lightly "grind" the crown?

Thanks!

Chris Ross
 
There probably aren't many on here that want grinding compound anywhere near their benchrest rifle's crown. It's best to take them to a gunsmith and have them properly recut. But, depending on how deep the dings are, you may help your hunting gun by lapping the crown like you mentioned. You may also consider a muzzle crowning tool for doing your own. I'm not saying these are the best or right ways of doing it though...just that you may see a great improvement over your damaged crown by doing it.--MIke
 
Several of the old gunsmiths I've known swore by finishing the crown with valve grinding compound on a round-head brass screw and electric drill.

Modern benchrest shooters swear by one design or other machined crowns, but there was a PS article a few years ago where the author sawed a barrel muzzle off at an angle and it didn't effect the accuracy...go figger.

Not trying to be snide though, but, on a Ruger factory barrel I doubt if minor nicks would effect accuracy on them. i.e. don't expect a marvelous improvement if you do recrown them.
 
JerrySharrett said:
Not trying to be snide though, but, on a Ruger factory barrel I doubt if minor nicks would effect accuracy on them. i.e. don't expect a marvelous improvement if you do recrown them.
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ditto. A Ruger either shoots or it doesn't. If it doesn't, I wouldn't waste any time on it. The last Ruger I owned, I traded it in with a Canjar trigger on it for a Rem. 700 classic in 7mm Rem Mag. I didn't take the trigger off before making the trade as if I kept the trigger, it might tempt me to buy another one. That was a long time before I ever started gunsmithing. Still have the Remington, but it's been a 7mm STW for years after shooting out the original barrel.
 
If you've got nicks and dings

on the crown close enough to the bore to be of concern, then you probably also have metal that's been upset into the actual bore itself.... assuming that it is impact rather than just mild scratching that caused the ding in the first place. And merely finishing the front surface of the crown won't repair this. Something on the order of .125" of the barrel should be removed and a new crown cut.

I discovered this quite by accident a few years ago when fire-lapping a Ruger 10-22 barrel. Next to a faint ding at the muzzle (looked like the barrel had been dropped or hit with something) , inside the bore was a bright semi-circle of metal from which the lapping material had removed blue, indicating that there had been a high spot there. Apparently whatever had caused the ding had also caused the invisible blemish inside as well. Oh, and btw, the barrel shot much better after lapping. But that's another story....

And if you have habitually pulled a cleaning brush back through the bore from the muzzle, this can cause wear too (and maybe some of the slight roughness you mention). So it would be a good idea in this case too to cut off 1/8" and recrown.

Oh, and if they've had a stainless steel brush used inside, might as well toss 'em.
 
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JerrySharrett said:
. . . there was a PS article a few years ago where the author sawed a barrel muzzle off at an angle and it didn't effect the accuracy...go figger.
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Jerry, before we got a lathe, I cut off a Remington .22 rimfire barrel with a hacksaw, then filed it flat. You can't really draw file a barrel crown, but you can come pretty close. Finished off with a brass screw and 240 grit in an electric drill.

When we later re-crowned that barrel in the lathe, the first very light touch of the tool showed the filing was dead on. It can be done.

Oh. It shot worse after we redcrowned it in the lathe, but I doubt that was the reason. It was a pinned barrel, and apparently the barrel was loose enough in the receiver that when I bedded it, some compound had gotten in and glued the barrel to the action. We pulled the barrel to recrown, and I didn't "re-glue" it.

Yeah, go figure.

EDIT: Oh yeah, If you do use a grinding compound, be sure it is aluminum oxide, NOT silicon carbide!
 
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Charles,

You make me feel good.

A twerp I know buggered up his SMLE just before a trip & asked me to put a new tube in it. He knew I dabbled in Enfield esoterica those days.

All I had spare was a No 4 barrel, so I ran it in, marked for a new extractor slot & quick bedded it for him with builders bog. Then he decided he didn't like the ssepdown on the barrel, so I cut it back by marking with a pipe cutter, sawing with a hard blade in a jeweller's piercing saw, draw filed/polished it & crowned it with an RCBS inside neck chamfering tool.

Dovetaild it for sights & bore sighted & it was the most accurate barrel he'd ever used.

Shesh!

John
 
Well, I've used a ball from a bearing about four or five times the size of the bore with fine valve lapping compound to repair a number of crowns. It's a little slow and aggravating but has always worked for me.
 
Fellows...fellows...Just because it worked perfectly doesn't mean that it is right ;) What would the world be, if we simply used that as the measure of what we ought to do. :)
Merry Christmas
 
John Kielly said:
Charles,

You make me feel good.

A twerp I know buggered up his SMLE just before a trip & asked me to put a new tube in it. He knew I dabbled in Enfield esoterica those days.

All I had spare was a No 4 barrel, so I ran it in, marked for a new extractor slot & quick bedded it for him with builders bog. Then he decided he didn't like the ssepdown on the barrel, so I cut it back by marking with a pipe cutter, sawing with a hard blade in a jeweller's piercing saw, draw filed/polished it & crowned it with an RCBS inside neck chamfering tool.

Dovetaild it for sights & bore sighted & it was the most accurate barrel he'd ever used.

Shesh!

John
Click to expand...

I have a customer that literally crowned his BR gun with a dremel tool. It didn't shoot too bad either! I dialed it in and recut the crown and it was back like it should be though, and did improve...just not as much as you'd think. I also own a Savage 17HMR that you can see with the naked eye that the crown itself is cut at about a 30 degree angle to the bore. It's bad enough that you can see the barrel is longer on one side than the other. I'll fix it one day but for now, it shoots under an inch@100 like it is. Go figure. I've also recrowned guns that the crown didn't look bad at all on but would spray bullets terribly...that the new crown made into tackdrivers.:confused: --Mike
 
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I cannot recall who made the comment that a crown was over emphasized in terms of accuracy...but I am moving to that school of thought myself as I spend more time accurizing rifles. If it's affecting accuracy, it's a big ding that you would not need 10x to see. As mentioned, the bore would be damaged.
 
David Sengelaub said:
what would you use silicon carbide for?
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Silicon Carbide is used for abrasive applications that require a much harder grit than Aluminum Oxide. Valve lapping compound is usually Silicon Carbide (Remember Clover Brand lapping compound). Silicon Carbide is commonly bonded to metal disks and used to grind Tungsten Carbide cutting tools whereas you can grind High Speed Steel with Aluminum Oxide wheels.

For example

http://travers.com/skulist.asp?RequestData=CA_Search&navPath=All+Products%2F%2F%2F%2FUserSearch1%3Dsilicon+carbide+grinding&q=block+id+105572+and+class+level3+id+30011&minPrice=$32.41

(you will have to copy/paste to use this-for some reason it will not post as a URL address?????
 
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Thanks to all for the comments - I learned several things. Thanks again!

Chris
 
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