Crowning a barrel

[timspawn]

This is a stainless 270 that came in the shop. I'm not sure what the guy did to the barrel but it suffered some type of abuse. I used a brass screw with lapping compound in a cordless drill. I know it's not great but it looks better than it did.

[rbertalotto]

sure does! nice work!

[country gent]

The ball and lapping compound works very good for final finishing. I fine file then finer grits of sand paper backed with a file to clean up helps alot also. Use an adjustable protractor and work around the barrel radially keeping it square. The the ball and lapping compound to finish the actual crown. That looks good.

[timspawn]

The ball and lapping compound works very good for final finishing. I fine file then finer grits of sand paper backed with a file to clean up helps alot also. Use an adjustable protractor and work around the barrel radially keeping it square. The the ball and lapping compound to finish the actual crown. That looks good.

With the method you are describing I could make the muzzle flat (which I would rather have) over the rounded shape it has now?

[DougGuy]

From what I could see in the first pic, it looks like it would help it to cut it back half an inch and recrown it.

[timspawn]

From what I could see in the first pic, it looks like it would help it to cut it back half an inch and recrown it.

That first picture looks real bad. There was some crud in the bore when I took that. The bore is fine all the way to the end but you may be right...less filing if just cut it off and start with a flat square end.

[country gent]

If you decide to cut it off and start over set the protractor up first, You have a sqyare to bore end or close to it now. This way if the saw wanders any you have the protractor set up to read true. Another toolmakers trick is to blacken the surface when cutting so you can see the files cut and judge what is being removed. The protractor will show the high side then you want to cut it more than the lower sides, a little black ink or lay out blue shows this and allows you to judge the cuts easier. Use a marker or lary-out blue that dries completely a spotting ink that stays wet will load the file badly. I have turned a piece of brass up with a 1" stem of lightly snug bore dia and a square face of larger than barrel dia and a stem on the back. This will show square to the bore when filing and when cleaned up and polished you can put a little lapping compound on the face and work it to a very nice square finish. Then crown with the Brass ball and compound to clean up the rifling. I perfer the reccesed crowns but they almost take a lathe or special tooling to create. A counter bore for bolts that uses interchangable pilots might work with the appropriate pilot turned up.

[timspawn]

Thank you for the info Sir.

[nanuk]

LEE case trimmer with the appropriate spud shimmed to bore diameter

[aspangler]

IF you have a lathe, recrowning would be really easy to do.

[timspawn]

IF you have a lathe, recrowning would be really easy to do.

Sadly a lathe is beyond my skill level.

[btroj]

I thought a lathe was beyond my skills for a long time too. Then I bought one and discovered it isn't any different from other tools, it takes some basic understanding of what to do and practice.

I haven't crowned a barrel, yet. I figure that at some point in the next year that will change.

[dragonrider]

I have these two tools, the large one will flatten the crown square to the bore and the other will create a 45 degree chamfer on the bore. They work very well with the proper pilots. If you can give me the bore diameter, not the groove dia, I will make some pilots and you may borrow the tools for the cost of postage both ways. I would cut enough off the end of the barrel to get rid of that giant radius on the outside then use these tools and then file a small 45 degree chamfer on the outside where the giant radius was.

[timspawn]

I have these two tools, the large one will flatten the crown square to the bore and the other will create a 45 degree chamfer on the bore. They work very well with the proper pilots. If you can give me the bore diameter, not the groove dia, I will make some pilots and you may borrow the tools for the cost of postage both ways. I would cut enough off the end of the barrel to get rid of that giant radius on the outside then use these tools and then file a small 45 degree chamfer on the outside where the giant radius was.

I will PM you once I cut the barrel.

Thank you,
Tim

[dragonrider]

Ok....

[dtknowles]

I know that there are a variety of crowns for barrels but I don't really understand why they are the way they are. I made some barrels for my Dan Wesson Mdl. 15 revolver. After turning and threading I cut them to length and cut the forcing cone but I left the muzzle as cut on the lathe. I looks clean and shoots good, what am I missing.

I also redid the crown on my Ruger #3. It came from the factory with machine marks almost up to the bore. I used a 3" x 3" square of half inch flat aluminum plate and some sticky back sand paper followed by fine sandpaper glued to the block wet with cutting oil. The end of the barrel is now mirror finish but I did leave a little of the old chamfer or whatever you want to call the old crown. It appears that I was able to keep the muzzle square and I now get nice lube stars. I have see a few different crowns but does one style stand out as best for accuracy. I have seen crowns call target crowns and they seem to have no chamfer and are just a sharp edge to the bore recessed a little.

Tim

[country gent]

Like alot of things with firearms, It depends on who you talk to there are alot of diffrent theroys and ideas out there. The recessed crown offers some protection to the actual crown. the radioused crown was easy to cut and machine easy with a simple form cutter. The actual crown is the blending of the bore/rifling to the barrel face. Alot of gunsmiths cut it on the lathe and finish with a brass ball and lapping compound as this leaves a sharp true edge with out the burr from cutting with a tool. I have cut crowns with the lathe and a very sharp fine HSS cobalt bit, A form cutter similar to what is shown above, and the faced muzzle brass ball method. I did use the brass ball and compound to final finish the others also. If you look at rifles you will see the full radious muzzle crown, a recessed flat crown an 11* muzzle face ( almost a form of recessed), and some have a flat muzzle with just the blending of bore to muzzle. All work if they are square and true to bore. I believe alot of bench rest rifle are set up with the 11* crown.

[dtknowles]

The 11 degree crown is what I think is on my two bench rest rifles if by that you mean that the angle between a plane perpendicular to the bore and the muzzle is 11 degrees with bore recessed. The transition from the bore to the muzzle is just a sharp edge. I have not looked at them under magnification.

Tim

[Ballistics in Scotland]

All that really matters with a barrel crown is that it should be the same all round the bore, and stay the same. For a military or hunting rifle that is likely to suffer rough handling, that may require a deeply recessed crown. - or much less will probably do. For a benchrest rifle that will always travel cased and with its muzzle protected, a totally flat muzzle with 90 degree sharp edges at the bore will be just as accurate as anything. The most accurate sporting rifle I ever rebarrelled was very accurate, till I finished the job, with a tiny burr on each land, created by the lathe centre Shilen had used while turning it to contour. Had it not been on all the lands, it might have been quite different.


The screw and grinding paste method will work for a shallow crown. (I would then tape over the muzzle and let some alcohol or gasoline stand in the bore for an hour or so, to get that residue out with as little scrubbing against the bore surface as possible.) But it just might wander off-center, and any more aggressive unpiloted cutting tool is much more likely to.

My favourite method is to use a ball-shaped tungsten carbide burr of double to three times the bore diameter. But I would hold the shank in a vice, and rotate the barrel or barreled action against it, by hand. Other than a lathe or piloted cutter, that is the surest way of keeping the crown concentric with the bore. If I had a piloted cutter I would temporarily stick it in side the muzzle with wax, and use its shank as, in effect, a stationary pilot working in the rotating pilot hole of the tool. I am not keen on rotating hard steel against that precious bore surface.

If you must have a recessed crown for a standard bore size, such as .25, .375, .5in., 6mm. etc., search on eBay for "counterbore" and "counterbore pilot". You might find something just as good as the gunsmith's tool, and much cheaper.