crowning

Butch Lambert · Jan 29, 2003

I indicate the bore on the muzzle end and use a very sharp, pointed tool, with a lot of rake to cut a 90 deg. crown. For crown protection on anything but a competition you might want to recess it. I don't think the angle of the recess is important, only it needs to be 90 deg. and then cut the recess. Thebarrelman

UKyankee · Jan 30, 2003

Butch,

Where do you grip the barrels? how do you ascertain that bore is running on it's true center and not off the outside diameter? Are you using a plug gage off the lands, or dialing in the run-out off the turned muzzle OD. Just asking so's' the folk get the full complement of your post..glad to meet ya barrelman, by the way..

Kurt Westfall · Jan 30, 2003

Can't answer for Butch, but I have two ways, indicate both ends with a gage pin in the bore, or one end using a indicator rod, can't say I can see any def in the two. I too use a resesed flat crown. Humm how about the rest of you guys, whats your prefured way for crowns and chambers?

[This message has been edited by Kurt Westfall (edited 01-30-2003).]

DickS · Jan 31, 2003

A round brass lap can deburr the edge of the bore. Theoretically, indicating off a gauge pin is best; if the exterior has been turned concentric to the bore, indicating off the exterior is going to be pretty darn close. I use Butch's crownng technique, and am satisfied with it.

Kent · Jan 31, 2003

After lots of experimenting I have decided crowns really don't matter much as long as they are square to the bore. Even not square to bore just moves groups on the paper but does not seem to effect group size.

This is not on bench rest guns but I have proven this to my satisfaction on 1/2 MOA rifles.

So I frequently use the Brownells piloted crowning tool if the barrel otherwise doesn't need to be removed from the action. If the barrel in in the lathe I just use the live center to set up the steady rest. I sometimes cut 90 degree crowns but usually just cut a 18 degree bevel.

[This message has been edited by Kent (edited 01-31-2003).]

mike thomas · Jan 31, 2003

If you are holding a tapered barrel in a chuck, little of the barrel will be touching the jaws. There may be some marring. Use a wrap or two of 10 AWG copper around the barrel where the jaws contact it to eliminate marring . Mike

GeneT · Feb 1, 2003

I agree completely with Kent. I like a recessed flat crown myself, with a little 45* chamfer at the bore. I'd suggest always indicating off of the bore, you just can't be certain about the outside of the barrel. Never used the hand-crowning tool from Brownell's but thought it might be handy for successively shortening a barrel while at the range.
GsT

Kent · Feb 1, 2003

Another place where the piloted tools are real handy is cleaning up something like a Garand or FAL which can be such a chore to remove the barrel from because of all the other stuff dangling off the barrel. Another plus for the Bolt gun over other styles.

I know in the old days some people would use a round brass ball chucked in a drill (electric or manual) with lapping compound to polish and clean up crowns. I know it is not really machining related but I have wondered if anyone has tried this? It seems it would be self centering and might work.

[This message has been edited by Kent (edited 02-01-2003).]

GeneT · Feb 1, 2003

Hi Kent,
I've lapped the crown on two rifles with a brass ball. It didn't do any harm, but it didn't make a noticeable improvement either. (One was, and is a 1/4 MOA rifle, so I thought if it made a difference it would be there.) My best guess is that it won't improve a proper crown, but may improve a bad crown or remove light damage.

doc · Feb 2, 2003

i know that everyone dials in on the bore to dead nuts but ,a 90 degree recessed crown is a LOT more forgiving of wobble than an 11 degree or bevel crown......have used large round head brass screws in a breast drill w/ valve grndg compound ( after hacksaw & filing to a square 50 yrs ago).....it worked.........it worked in a lathe rotating by hand ,even worked w/compound on my thumb(oh ,no mr bill)

if using a stdy on a finished barrel, a split clamp bored for taper , w paper under , is only way i was able to protect blacking( used to put a shldr on it to bear against stdy to help hold back when working betwen centers w/ dog ( well ,u could drive a solid one on w/ paper ,carefully, i guess)

best wishes
docn8as

UKyankee · Feb 2, 2003

The 'brass ball' method can be employed on a lathe as well, should be for that matter, if possible. The finishing touches on the crown can make all the difference, I've seen markedly better results with proper crowns. Main thing is to keep the crown square to the bore, make sure it doesn't go into the rifling, and watch to make sure you aren't burring up the corners of the groove/land intersection. 11*, recessed, I don't think it makes any difference what type of crown it is, one doesn't shoot any better than the other, whatever fits the situation the rifle will be used. A crown protects the muzzle from damage, and should provide a clean break when the bullet leaves the bore, nothing more, nothing less..

Butch Lambert · Feb 2, 2003

I'm sorry, I've been away. I use deltronic pins and have a cathead on both ends of the headstock. I made collets to fit over the barrel for the screws in the cathead to ride on. Butch

GRUNING · Feb 2, 2003

A LOT DEPENDS ON JUST WHAT IT IS TO BE CROWNED, TARGET,HUNTING, OR TACTICAL. IF LIVES DEPEND ON ACCURACY, BE AS PRECISE AS POSSIBLE. AN ADJUSTABLE BUCK CHUCK, IT CAN BE ADJUSTED AS A FOUR JAW BUT THE TORQUE WILL BE THE SAME AT EACH JAW. KEEPING THE SAME AMOUNT OF PRESSURE ON EACH JAW THE CHANCE OF UN-EQUAL STRESS ON THE O.D. OF BARREL IS ELIMINATED.
USING A TEST INDICATOR IN THE BORE, YOU WILL CHECK THE BORE/RIFLING CONCENTRICITY AS WELL AS TRUING TO BORE FOR MACHINING. IF POSSIBLE, INDICATE MUZZLE AND BREECH. SOME FORM OF ADJUSTMENT AT THE REAR OF THE SPINDAL HOLE IS HELPFUL(CHUCK,SPIDER WHATEVER). IF THE BARREL IS TAPERED, DUPLICATE THE TAPER ONTO A SET OF SOFT JAWS.
FACE MUZZLE FROM BORE TO O.D. SO BURRS ARE NOT DEVELOPED. USE A CLEAN SHARP TOOL WITH A SLIGHT RADIUS.
HOPE THIS HELPS

[This message has been edited by GRUNING (edited 02-02-2003).]

Lefty · Jul 6, 2003

There are many ways to skin a cat, and this is only on of em.
I would dial in the bore at the breach end of an un-cut barrel (measuring of the grooves not the lands) and cut the outside diameter on the same axis. Then when mounting it, dial it in again using the newly cut outside diameter and dialing in the muzzle bore (providing the barrel is straight).
Other than that, as with a barrel that has already been chambered, dial it in as deep as you can from the muzzle (the deeper the better). Then dial in the muzzle. Adjust the barrel until there is no run-out beteen the two. Now you are ready to go to work.
Oh... forgot one thing... About using brass with compound? It works great if the problem is that the barrel has some rough cuts or burs from tooling which copper or lead would not smooth out. But if you have a damaged muzzle, depending on the damage, it can cause the center of the brass to be off rendering the muzzel out of square. In this case... better to re-cut it.

[This message has been edited by Lefty (edited 07-06-2003).]

Butch Lambert · Jul 12, 2003

I guess that I need to tell you what I do and why. I have a cathead on either side of my headstock. The screws on bothe sides ride on collets that I make that slip over the barrel. I use a deltronic pin slipped into the bore. I first put my indicator next to the muzzle end and adjust the runnot with my cathead on the chuckend. I then move my indicator to the far right of the deltronic pin and use the cathead on the lefthand of the cathead to remove the runout. Indicating off the lands is the part of the bore that is machined. The grooves are either cut with a cutter after bore and reaming or after pulling a button through.

rws · Jul 14, 2003

Butch is right on...

Indicating by the use of pins is the way to go. Trying to indicate on the grooves is a pain at best. With a match grade barrel, if there was a notable difference between the groove and land dimensions, I would send it back.

By indicating with an extended pin, and truing both ends of the pin via "catheads", aligns the work with the portion of the barrel which the bullet is in. This goes for chambering too. Anything other than 90 degree crown, whether recessed or not, is just more work for no gain in results. And, NEVER touch the crown with a ball, lapping compound, handheld tool, etc. Nothing you do will be more precise than what you cut while in the lathe. Any burs that may exist from crowning will be gone after the first one or two shots.

Lanmanb4 · Jul 24, 2003

I think this was where it was mentioned when crowning to take a shop roll of emery wet /dry sandpaper and put the grit is out towards the posts on the steady rest and let the barrel ride on the clothe side with lots of lube ..

All I can say to that is ..

MAN OH MAN DID THAT WORK WELL !!!! THANKS !

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