The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Gunsmithing Dailing in a barrel for crown or chamber work?Go | New | Find | Notify | Tools | Reply | |
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Can anyone give me some advice on how to set up a barrel in my lathe for recrowning. I have been told that I will need an independant 4 jaw chuck in order to get the hole centered since it is often out of center in relation to the external profile of the barrel... Any suggestion? How would a recrown turn out if you just stick it in the 3 jaw chuck and go for it? | ||
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Many use "Range Rods" that have live pilots and, are taper ground, to insert in the bore and then indicate off of the rod. Others insert the "Needle" or "Feeler" of the indicater into the bore. When using the latter method, the lands and grooves are to be dealt with. Some times odd numbers of lands and grooves make using this method difficult. Manson, and other toolmakers, offer a hand, or drill, operated crowning tool that utilizes a pilot to follow the bore. | |||
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Results would depend entirely on how accurate your 3-jaw chuck is and/or whether or not the the bore is concentric with outside of barrel--very few are. Do you feel lucky? John Farner If you haven't, please join the NRA! | |||
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Good answer Toomany Tools... I think the "range rod" seems to be the easiest solution. | |||
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If you are going to face off the end of the barrel, from the bore out, it does not have to be exactly on center. Being .010 or .020 off center will not be a problem IF you have a 90 degree crown. However, if you want to do an 11 degree "target" crown or a small 45 deg. or other angle crown, you have to be on center. | |||
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I myself use a 4 jaw. But if all a person has is a 3 jaw, then that is what he will use. I use a "Circle" brand boring bar with carbide inserts to cut crowns. That will work for both 3 and 4 jaw jobs.  Without going into heavy detail about using a spider on the back end to adjust for the angle of the bore, what you would likely do if all you had was a 3 jaw, would be to mount the barrel in the 3 jaw, and make a facing cut to the barrel from the center out. Put some marker or layout fluid around the breech end from the bore out. With the barrel spinning, insert the tip of the tool just barely (.05) inside the bore, and using the hand feed, slowly bring the cutter into light contact with the bore. Back the tool out, stop the lathe and have a look at the bore. You will see where the tool made contact and where it didn't. You will need to move the "virgin bore" towards the cutter. With a 3 jaw, you do this by placing shims between the barrel and the jaw on the side where the cutter missed. Unless you are off a mile, I would recommend using paper as shims, as the change is subtle. You can use business cards if necessary, anything as long as it doesn't mar the finish. Depending on how good, or, lucky you are, you will need to shave a few thousandths off the face to re-establish a clean surface to check the progress of the alignment. Once you have it as close as you can get, go for it. If you are careful, pay attention and go slow, you can be reasonable assured that your 3 jaw crown will beat the hell out of anything the factory is sending out. Good luck. If you need pictures, I have them. _______________________________________________________________________________ This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life. | |||
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Malm, if anyone else cares, that DOES work! It may seem a little confusing to someone that doesn't work with machinery but if you try it you will see the light. Jim Kobe 10841 Oxborough Ave So Bloomington MN 55437 952.884.6031 Professional member American Custom Gunmakers Guild | |||
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The new lathe I bought when I started uo crapped out on me. Luckily I had a backup but it was intended for roughing work and I didn't have a 4 jaw for it. Malm turned me on to the paper shim trick and I'll attest that it works like a dream. That trick got me through until I could buy a nice new 4-jaw. I also like his statement that it'll be better than any factory crown, that's for sure.  Aut vincere aut mori | |||
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Reading these machinig posts is always great motivation for me to either do one of two things... Simplify my gun inventory or keep working harder cause I have no freaking idea what you guys are even talking about an dbetter be able to pay somebody to do this stuff... I figured a 4 jaw chuck was some kind of cut of beef I could get from the butcher for a pot roast recipe. Mike Legistine actu? Quid scripsi? Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue.  What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | |||
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Malm, If my 4-jaw gets broken or stolen I'll remember your trick--it's a good one. I seem to remember posting on another thread that we learn to use the tools we have; here's another example. John Farner If you haven't, please join the NRA! | |||
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In the past, before the acquisition of a 4 jaw, I had even resorted to using carbon paper and aluminum foil to bring the bore that much closer to center. It's funny the things folks will resort to, to get it right. _______________________________________________________________________________ This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life. | |||
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In honor of this threads topic, I went to the shop and cut this crown using a 3 jaw with paper shims. This is the result. Of course, now I have to place it in the 4 jaw to correct it before sending it back.  _______________________________________________________________________________ This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life. | |||
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Thanks for that Westpac! Only thing is, I can't see what the problem is there. How much runout did you get before shimming and how little did you get by shimming in the 3 jaw? Where is the imperfection in that crown? Cheers. | |||
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Looks has nothing to do with it.....what you can't see has to be measured and rarely will you get it right on a 3 jaw, simply because the stresses that become apparent in the turning of the barrel cause the bore to not be concentric with the OD. On a crown, I use a 4-jaw and some shim stock with a set of precision gage pins to just slip into the bore. Dial off of that until I'm within .0001 TIR....Similiar with chamber work too, but you can't rely on the OD anytime for real precision work. Williams Machine Works | |||
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Express, there is no imperfection in this crown. I was being facetious. Using a pin gauge in the bore, I was initially out .010. I am within .001 as you see it. They don't always come in this good. That's why I use a 4 jaw. It allows you to creep in even closer. But with a little care and a good 3 jaw, you can get exceptional results when compared to anything coming from the manufacturers, and even those produced by a shit load of gunsmiths for that matter. _______________________________________________________________________________ This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life. | |||
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I figured so...Just how close do you need to get before you can call it a "good" job? | |||
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Like other aspects of a barrel, concentricity is key. The bullet has to leave the bore straight and clean, and the gas must be directed away from the bullet as evenly as possible so as not to influence it's flight. Everyone has their standards. For me, I charge people to crown their barrels, therefore I give them as close to a perfect crown as I can get. _______________________________________________________________________________ This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life. | |||
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You can very easily make up a spider for use in the three jaw chuck as well. Regards, Bill | |||
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this is a dumb question and you can say so if you want, but are bores always perfectly round? | |||
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Pretty much! Butch | |||
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Considering the nature in which they're made, the likelihood is on your side for it being round. Not always the case, but more times than not. Williams Machine Works | |||
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I put an Interapid .0001" resolution test indicator on a magnetic based Noga indicator holder. I use a 9" 4 jaw Buck Chuck. I also have a self centering 10" 6 jaw Buck Chuck, but I do not use it for crowns or chambering. If you can center it to within .0001", please come over and show me. I indicate on the the grooves between riflings. After I cut it with the lathe, I polish it with a Scotch Brite cleaning pad. Varmint Al does it differently: http://www.varmintal.com/ashot.htm
I think what Al is doing is breaking the burr on the edge, like in sharpening a knife. I hope my cleaning pad does a little of that. To inspect the edge, I light it with Nite Ize and look through a cannibalized binoculars' eye piece [Cheaper and better than a jewler's loop].   | |||
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just send it to saeed he will use his four jaw deburring and chamfering tool for your crown  in times when one needs a rifle, he tends to need it very badly.....PHC | |||
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