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Post by tpcollins on Jan 23, 2009 13:46:41 GMT -5
I thought there was a gunsmith section on the old forum but nothing now. Anyway, I was reading online where the crown of a rifle is very critical because it's the last thing a bullet touches when it leaves the barrel - makes sense to me. I've checked the crown on a few of my firearms with the suggested Q-tip procedure and didn't finding anything alarming. These articles suggested taking your barrel to a gunsmith if a new crown is required.
Couldn't you lay a piece of thin piece of oily leather over the muzzle, chuck a tapered wooden dowel into a drill and slowly sort of "lap" the crown area to remove any potential sharp edges or would this screw it up royaly? Thanks.
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Post by youp50 on Jan 23, 2009 14:36:08 GMT -5
I would not do that. Wait for Richard, he will set you straight. If he doesn't post PM him.
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Post by KerryB on Jan 24, 2009 10:19:59 GMT -5
I have read many times over the years that you could use a properly fitting round head brass screw with a little lapping compound to touch up the crown. I have never had the nerve to try it myself! I guess it wouldn't hurt anything since if it didn't work, you could go ahead and have a gunsmith do it again. KerryB
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Post by ozark on Jan 24, 2009 10:43:43 GMT -5
If the crown is not perfect it permits gases to escape earlier in one place than consistently all around. This can cause the exiting bullet to be pushed to one side during exit. Spin would quickly stablize the bullets flight and it should be consistent. I have used valve grinding compound and a brass screwhead as mentioned by KerryB to polish the crown area. Never had any noticable ill effects. The crown naturally should be as perfect as possible. Ozark
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orion
8 Pointer
Posts: 128
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Post by orion on Mar 5, 2009 13:24:26 GMT -5
Youp is correct, if you want it done right buy a crown cutter or send it off to someone who knows what they are doing. However, if you know one is bad you have nothing to lose by attempting it yourself.
I admit I have butchered a lot of home gun smith jobs over the years becasuse I was too cheap or in too big a hurry, so you may want to listen to someone else. I have heard of the various screw, glass rod, etc. methods of lapping a crown, but have never tried it. I once cut the barrel off a cz 452 .22 rimfire with a hack saw, filed the end straight as possible with a mill bastard and then took my RCBS case chamfer tool and ran it over the crown numerous times. It did not remove a lot of steel: however, you could see a slight crown (darn that cz steel is hard). That thing shoots better than ever, and I have never messed with it again.
Good luck, if it isn't broke don't fix it.
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Post by screwbolts on Mar 6, 2009 9:19:19 GMT -5
The Brass screw and Lapping compound have worked well for me for years. ;D I actual chuck the screw in a drill, have the barreled action vertical with lots of light available . I would suggest you plug the bore with cleaning patches to catch the excess oil and compound. I Dilute the grit with oil or water depending on the base of the grease carrying the grit. Start at a slow speed with light pressure let the grit do the cutting roll the screw around the head to help it stay uniform. It won't take long and you will be proud of your work. Clean it up well and REMOVE those patches. ;D Yes, you can buy special cutters$$$ and bushings$$$ to guide them in the bore. I could even cut the crown on the lathe, but I have always used a large Brass screw! ;D I did the crown on my .357 Mag Rook rifle with the Chamber reamer, thereamer I Chambered it with. that will also work! ;D ;D Ken
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Post by ozark on Mar 10, 2009 21:06:14 GMT -5
I don't consider this task beyond the means of the ordinary handy man. I have met many gunsmiths and practiced as one a few years. They are not all good or that knowledgable. Some just go to work without any schooling or work under a qualified person. Crowning is interesting but when you consider such things as boattailed bullets, flat based bullets, champered bullets, sabots and such there are several varables. I have experimented with altering the crown to determine if it changes the point of impact. It has but beyond that I found that accuacy was not altered that much if any. Ozark
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Post by ourway77 on Apr 9, 2009 13:35:56 GMT -5
A lot of people think becaus a rifle looses accuracy they get rid of it or re-barrel the rifle. A bad crown is a main contributer to bad accuracy. Most people clean fromk the muzzle, and depending on the rod they use will definitly ruin a good rifle. As stated what have you to loose. Try the method, if it works all to the better. If not you are back to squre one. Then have it recround. I would try it and believe me if anyone can mess up a good thing it's me. Lou
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Post by boarhog on May 21, 2009 16:47:05 GMT -5
A friend of mine bought a Browning semi auto .308 Win at a gunshow. When he got it cleaned up, there was a bad bulge 2-3" from the muzzle. He came by my shop, put the barrel in my vise, and sawed the barrel off with a hacksaw. I then put the barrel in the vise vertically, filed the rough cut as smooth and level as I could by eye, then put a brass decorative thumb tack in a drill and used valve grinding compound to re-crown. I thought it would be a miracle if the thing would shoot less than 6" groups, but later that day, he came by to show me several 1-1 1/4" 3 shot groups using various loads. He dubbed that rifle "Hacksaw" and it became his favorite deer rifle!
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Post by chuck41 on Jun 4, 2009 14:19:58 GMT -5
I have heard of doing it with a marble coated with oil and a bit of lapping compound. Placing it in palm of your hand and rolling it in the end of the barrel. That might work as long as the barrel end was absolutely square but I never felt it was worth a risk to one of my rifles. Only really good thing is if the crown really needs to be touched up, it really can't damage anything that you don't already need fixed anyway. That marble won't touch anything but the inside edge of the crown.
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Post by Tarheel on Jun 6, 2009 23:02:59 GMT -5
I have a Browning Bar .30-06 that had little pits in the crown edge. I had it re-crowned by a gunsmith and it began shooting better right away. Midway has re-crowning chamfers and cutters with the brass or steel pilots real cheap but they are out-of-stock.
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Post by Richard on Jun 29, 2009 16:25:48 GMT -5
Most of what has been posted will do a relatively "decent" job. For a benchrest shooter/gunsmith, there would be a lot of "cringing and hair pulling!" ;D When I crown a barrel, I set it up in my lathe thru the headstock and use and indicator on both the muzzle and the breech end. A special bore indication pin is inserted for the tip of the indicator to ride on. You NEVER indicate off the exterior of the barrel since it is almost never parallel to the bore. The exterior will usually indicate several thousands different. You always want to indicate off the bore. Once your bore is running true, you would then use a special shape and sharpe tool bit to cut the crown. 90* to the bore or as some do, 11*. One is as good as the other. Just personal preferences. If your barrel is not perfectly indicated, a 11* crown will be "lopsided!" Not good! Whereas a 90* crown will still be 90*. What I do after carefully and slowly making my final cut is this: I take a ball bearing somewhat bigger than the bore and press it against the "turning" bore under a piece of #400 wet/dry sandpaper with cutting oil. I run the lathe both in forward and reverse. This will eliminate any tiny burrs that might have been left from the cutter. Now, check your work with a Q-tip and see if there are any burrs??? The marbles and brass screws are fine for just "crisping up" an already decent crown, but not for taking serious nicks out. The hacksaw and file are kind of crude but could work to some degree Obviously you would not be entering this rifle in a benchrest match ;D And, you would not be doing it to a $350 custom barrel. Richard
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Post by Tarheel on Jul 5, 2009 20:41:13 GMT -5
I called Midway USA and the lady said that the out stock crown cutters will be availabe mid-August. The also have the stop collar and bore pilots for almost any bore
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Post by rossman40 on Jul 6, 2009 14:48:35 GMT -5
Richard pretty much hit it on the head. I agree a ball bearing would be a whole lot better then a screwhead. The screwhead is eliptical where as the ball bearing is uniform round. The ball bearing being harder would also keep its shape better then a marble. A old smith I watched in the 60s would use a ball bearing which was welded onto a rod and the rod stuck into a wooden handle. Used it much like you would use a hand valve lapping tool, spinning it between the palms of his hands. Another smith would have the barrel indexed in the lathe, cut the muzzle face and then use like this plumbob that would be in the tailstock to lap the crown. He would then use a hand microscope (like 30X, it was hard to use a jewelers loupe around the lathe) to exam the crown to see if it was uniform and the right dimension. If it wasn't uniform he would reface the muzzle and start over. The reason he used the plumbob was that he was a stickler for the angle of the crown, 45 degrees for flat base bullets and 60 for boattails. His theory was the 60 degree for the boattails reduced the amount of laminar air flow of the muzzle gases around the bullet (pretty hi-tech for over 30 years ago), whether it made a difference nobody could tell but it sounded neat. I learned old school and later when I got into manly mans guns (40mm and bigger ;D ;D) all the pieces fell into place a whole lot easier for me. What everybody calls the crown nowadays I was taught it was the muzzle face and that little bevel is the crown, The types of muzzle faces (radius, stepped and 11 degree), while they are the base for the crown they also have a primary job of protecting the crown. Without the crown we would have sharp edges that would eat cleaning rods, patches, ramrods and perhaps human parts. A sharp edge would also be more susceptible to damage and erosion by muzzle gases. By far the big killer of crowns is cleaning rods and in the case of MLs ramrods. Early target shooters knew the importance and high end MLs had false muzzles for loading and cleaning which even carried over into cartridge guns like Ballards, Brownings and Remingtons of the Creedmore days, The little knob is designed to block the sight picture so you would not fire with the false muzzle on. Of course there are modern versions and protectors which are cheap insurance,
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Post by rjhans53 on Jul 16, 2009 8:21:08 GMT -5
I went thew a period in my life of buying old mausers and making them into hunting rifles (learned the hard way no mater what you add to a pigs ear, it's still a pigs ear). I finally gave up on all the various methods of installing a crown and bought a 11 degree crowning too. They all seem to work to a point, it's your call.
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