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Hi, I am chambering a new barrel for a 250 Savage using a piloted reamer and a flexible reamer holder. Half way done and I decided to check the concentricity - it is running about 0.005" out of round. Why? I have no idea. The end of the chamber needs to be enlarged about 0.015". To save the project do I ditch the reamer holder and just use a pusher, relying on the pilot to get it back in line or try to bore it out to get it back into concentricity or make it into a 257 Roberts? Or start all over with a new barrel? Thanks | ||
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My thoughts are: How did you set up the barrel, and align the bore concentric to the lathe? How did you measure the concentricity of the partially completed chamber? Concentric to bore of lathe, or compare diameter across multiple axis's of the cut chamber? Where did you measure it? When you say flexible reamer holder, do you mean a rubber collet type holder, or a floating reamer holder that allows the piloted reamer to self align with the bore axis, but off of the lathe axis? As far as how to correct? I'd align the barrel bore with the lathe axis exactly. Then, you could bore out slightly to get the chamber back concentric to the now aligned bore and lathe axis, and then start the reaming process again, using a floating reamer holder. | |||
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It is through the headstock with a 4 jaw and spider. Range rods to center the bore, both ends. Measured the run out at the mouth of the partially completed chamber. Used a floating reamer holder. Thanks | |||
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Could be the bore is running out the deeper you go Jim Kobe 10841 Oxborough Ave So Bloomington MN 55437 952.884.6031 Professional member American Custom Gunmakers Guild | |||
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I'd measure the chamber itself, with a caliper across multiple points. When you say you measured runout, that says to me you used a dial indicator and spun the barrel. That tells you if the chamber is on the rotation axis, not if it's round. If it is round and just not concentric with the axis, I'd just continue to finish the chamber. That just indicates the bore isn't perfectly straight with the axis you've chosen for the barrel, and the floating reamer holder is doing it's job and aligning the chamber but keeping it round. If the chamber is out of round, I'd put a tight fitting rod down the bore in front of the chamber, and check it for runout. If the bore is on axis, I'd bore the back of the chamber out concentric, and then try the chamber reamer in a jacobs chuck, instead of the floating reamer holder. Do a little bit of cut and measure to see if the problem returns. A reamer held in a jacobs chuck will cut precise if the bore is perfectly indicated, but will cut oversize if the bore is off center. If the bore is far off center, it can break the reamer. Thus the use of floating reamer holders generally. | |||
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| one of us |
I don't trust floating reamer holders at all. I use a center in the tailstock to keep the tail end of the reamer in line with the bore. Assuming your tailstock is not offset. The only time a floating reamer holder gets any use is if I am rechambering a rifle .. you have no good way of centering anything, you are dependent on the prior gunsmith's work, so the pilot has to do the job. I believe the reason these floating holders don't work is twofold: 1 the pilot is never a perfect fit with the bore, it's usually sloppy to some degree, allowing the reamer to run off center. 2. Even if it is a perfect fit, the handle pushes the reamer off to one side so you get an oversized chamber. And you can't fix that by alternating the handle position. Russ Gould - Whitworth Arms LLC BigfiveHQ.com, Large Calibers and African Safaris Doublegunhq.com, Fine English, American and German Double Rifles and Shotguns VH2Q.com, Varmint Rifles and Gear | |||
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I agree. I never use one. A floating reamer holder is like throwing clay making a pot. There is no assurance the chamber will be perfectly concentric. At this point I'd make the bore true to the rotation and use a centered tailstock to try and correct it. IF not set it back. | |||
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Me too; I do it like RG does. I had a floating holder; didn't trust it and threw it away decades ago. | |||
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RP and DPCD do it pretty much the same as I do. I hold the reamer against rotation with a 6" crescent wrench held in my left hand, and feed the tailstock with my right. Holding the reamer by hand gives you a feel for how it's cutting, and if it's chattering, and lets you adjust the feed rate to help correct. This method is about halfway between using a floating holder, and using a jacobs chuck to hold the reamer. It lets the pilot align the reamer, but the center in the tailstock keeps the reamer tail on the axis of the lathe. | |||
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Vise grips for feel; I need to feel them cutting. | |||
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Thanks ssdave. The chamber is round, just off the axis. A fired case, fired from another 250, is a tight fit with no wobble. You guys have a lot more experience than me, I appreciate your input. The tenon isn't long enough to start over. I don't have a boring bar small enough to bore it out so I ended up continuing to ream it. So either centering on the bore with a range rod to 0.0002", at both ends, didn't work for some reason or the bore wasn't straight over the depth I reamed. We'll see how it shoots when I finish it up. My tailstock is about 0.010" too high so for my next one I'll make the tailstock fixture Hambly-Clark wrote about and ditch the floating holder. Thanks | |||
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If your tailstock is too high, have you measured to make sure it is parallel to the ways? If it keeps the same height as you extend it out, then it really is too high. Other possibilities are a twist or bend in the lathe ways due to improper base mounting or damage. I'd put the effort you are going to put into some kind of tailstock fixture into loosening the headstock and shimming it up to the tailstock height instead. Or whatever other fix is needed, after you've evaluated why the tailstock height is off. It would be terribly irritating to have every piece you turn on the lathe be tapered because the tailstock isn't right. Do a google search and you'll find a machinist site somewhere with the procedures to square up and correctly set up a lathe. | |||
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It sounds like everything worked out. I know everyone does it differently. But when I indicate in the barrel I use a longer range rod and just focus on the section of the barrel that's going to be reamed and a couple inches in front. This usually makes the muzzle of the barrel run slightly out. I just mention this because if you're indicating both ends of the barrel there will likely be some run out by the end of the reamed section. That said, many people do it this way and it works perfectly well.
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Abraham Lincoln is said to have claimed "If I had six hours to chop down a tree, I'd spend four of that sharpening my axe" So...invest in a precision level and set up your lathe "dead nuts" then Have a test bar about 2 feet long or longer. Take a cut at chamber end and then at tailstock end. (Between centers) When each end is identical, your lathe is properly set up and chambering between centers can't help but cut a true chamber. | |||
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Many ways to skin this cat. Your runout could have been due to your setup moving a bit. A tailstock is only "in alignment" at the given spot on the bed that's selected on a used machine. Bed wear is uneven. Align the tailstock with a test bar one foot from the spindle- it'll be out of alignment when moved from that position. I have (and still do on occasion) put the (trued) muzzle end in a collet and chamber in the steady. Any misalignment of the tailstock is mitigated over the length of the barrel. If you hold the breech in the headstock, there is no way to compensate for any misalignment if you're holding the reamer in a rigid setup. I still prefer a floating holder... I couldn't care less what the muzzle end is doing, I dial the two points just ahead of, and behind where the leade will be. I do a light pre-bore with a skinny carbide boring bar to true the bore at the breech with what I just dialed a couple inches further up so the reamer starts into a concentric hole. Manson floating holder, and flush system take over from there. | |||
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Well...I'd be curious to learn just how much the "bed wear" actually, in the real world contributes to tail stock misalignment, This seems to me to be in the land of smoke and mirrors...but..If you've tested out this theory, and can prove detrimental results, willing to listen | |||
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My old Clausing has practically no wear on the ways that the tailstock rides on, but I do have a little wear close to the chuck Where the carriage sits. I chamber in the headstock and make my first measurement in each end with Deltronic pins. I drill and reach in with my indicator and check the throat area and adjust if necessary. I taper bore to the indicated area. I push my reamer and want it to follow my prebored hole. | |||
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Disclaimer: I do not build rifles!!!! (This is what I do now to consume time and waste money)  Below photo should add to the controversy. Parker Ackley:  I am thinking some of you have never seen a "Industrial" floating reamer holder.  Hint: The bottom two in the photo are useless.  Oh yea, one of these critters just might help a guy out:  You gents do have floating pilot reamers with pilot bushings, for each bore size, in 0.0002" increments, right???   I will close with: "Test bar, where in the hell is your test bar???!!!!!!????" | |||
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Damn Duane, we think alike!!! Two of my three lathes have induction hardened ways. No way will I ever wear them out. Number 3, a 1907 South Bend, has iron ways but still is tight and turns straight:  | |||
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I don't do this for a living or for anybody except for myself. I do have an "industrial" reamer holder, but only trust my pusher. To each his own as we have each tried different methods before settling on our present method. | |||
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I agree with Butch! | |||
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 Here is a cheap Chinese mini lathe I always check a turned center in the headstock end first and than check the tailstock center to make sure that it is on line. Next the barrel in setup in the lathe using my home made 4 screw chuck and spider on the opposite end with barrel on center. Dial all parts to be as true to run. I use my own made floating reamer holder and a reamer with solid pilot as a guide to line up with the barrel center. This chamber was very good without any problems. This barrel is on my 204 Ruger and at 8 lbs will group under .300 in. at 100 yards with ammo loaded for a different rifle. Neck sized ammo only and reloaded for another barrel, so I was testing the rifle at the range and thought I would see what the older loaded ammo would do in the new barrel. It is as good as I could make for field hunting PD's.  I have used floating reamer holders for years and never had a problem using this one. I don't understand where all say that they will not use these tools. | |||
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It would seem to me that anything that allows a reamer to "float" into alignment will also allow it to "float" out of alignment depending on whether or not any resonance sets up when pushing the reamer into the bore. "Peace is that brief glorious moment in history when everybody stands around reloading". | |||
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Only if your setup is poor. | |||
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Duane, If you really want to get into smoke and mirrors, listen into a group of toolmakers, mold makers, and gunmakers babble about accuracy and precision. I have a good friend who everything he does is a tenth or two. Until I am standing next to him, or over his shoulder. Another friend and I had a light hearted argument about nearly this exact topic. He doesn't know how to run a lathe but he wanted to tell me how to run mine. I made him a small wager that I would chamber his barrel however I wanted, and since it was a hunting rifle, I would guarantee it shot 1/2 MOA. I promised to rechamber the barrel for free if it didn't. I set it up in my lathe and thread and fit the barrel to the receiver like normal. Pulled the barrel out of the lathe and put it in my bench vise. Took my Dewalt 20v cordless and predrilled the chamber, then reamed the chamber. I finished the last .003-.005 by hand to where it would just barely close on a GO gauge. I wasn't surprised at all that he reported it shot just under 1/2" at 100 yards. How much does bed wear REALLY effect it? I've chambered a lot of barrels on one of my lathes that has a fair amount of bed wear. I know one off the top of my head that placed 3rd at a pretty large PRS match shooting out past 800yds. That 6BR is quite an amazing rifle, and with its owner behind it, quite a deadly combination. Nathaniel Myers Myers Arms LLC nathaniel@myersarms.com www.myersarms.com Follow us on Instagram and YouTube I buy Mauser actions, parts, micrometers, tools, calipers, etc. Specifically looking for pre-WWII Mauser tools. | |||
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Fal Grunt, good post! In the same line I remember reading an article by a 'smith up in Virginia where he tested an old PPC (I think) barrel he was taking off by sawing the muzzle off at different angles to see what difference a crown really made. While the groups moved around with different muzzle angles the size of the group didn't change. I think we all like to add some "smoke and mirrors" to what we do from time to time. "Peace is that brief glorious moment in history when everybody stands around reloading". | |||
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What does bed wear have to do with chambering a barrel?I sure would like to know. | |||
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Butch, it's like fly fishing. All about appearance, and results secondary. You can't fly fish unless you have the uniform: Waders. Outfitter shirt with logo. Vest. Hat with correct logo. Sunglasses. Right pole, reel, line. You can't gunsmith on the internet unless you have a perfect setup, machines perfectly set up, the exact right magic tooling. I've chambered a few hundred barrels on my old Atlas 10x54 lathe. Has some bed wear, a lot of slop in the crossfeed and half nuts. Small headstock, have to hold the barrel in the steady and no spider to center the muzzlen end because it won't go through the headstock. I've recently acquired an 11" Logan, no wear, no slop, and huge headstock through hole (1 5/8" or so). It will be an incredible luxury to have the less worn, much more ridgid lathe and ability to center muzzle through the headstock when chambering. But, I would have never learned to do what little I know if I'd waited until I could afford and buy the "right" equipment. The reality is that gunsmithing is on the lower end of precision machining. It's great to be able to hold incredible tolerances, center amazingly well, etc. but in reality you can make a pretty good shooting rifle with pretty low precision and not all that good of equipment. | |||
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| Administrator |
We have always used the reamer in the tailstock and fed it into the barrel. Never had any problems, and every rifle we built would shot extremely well. | |||
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Thatg did it ! You're off the forum! You violated the code of common sense (meanlng you used it )...HAR! | |||
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