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Just finished a Lothar Walther barrel

 
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  #1  
Old 05-14-2008, 05:20 PM
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Just finished a Lothar Walther barrel

Learned several things about the 17-4 PH Walther barrel. I used a hi-speed steel parting-off tool and chamber reamer, and carbide turning and threading tools. Overall, the barrel had a "crunchy" feel and sound with either type tool, and the finish was not as smooth as 416 stainless barrels. The reamer is a fixed pilot .30 x .378 Wby finisher (Clymer) that had only cut 3 chambers. 40 rpm with my normal feed rate actually tore small chunks off the shoulder face and made a rough looking neck and body wall also. Tryed different speeds and settled on 63 rpm. Neck and wall finish were acceptable but the shoulder face was still too rough. By feeding only .025" deep between cleanups and slowing the reamer feed way down (enough to risk rubbing and work hardening the surface), the shoulder face was acceptable and the body wall actually got very nice. I have a Hawkeye borescope that I use to check the chamber appearance as I go. I only had "black magic" threading dope, so couldn't try different cutting fluids. There probably is something better.

This barrel took approx twice as long to chamber as a 416 barrel. Just over 7 hrs, in two sessions. I like the physical properties of 17-4 for a barrel, but am not sure yet that they warrant the extra work. This barrel also had the Blackstar treatment, and the bore is measurably oversize. With a G.I. .30 cal bore gage, I got .3005"-.301" land diameter, with a slight steady taper tightening toward the muzzle, thank goodness. Dave Manson recommended a replaceable pilot reamer because the fixed pilot would probably be too loose in the Blackstar barrel. He was right, but I had a .0005" bore runout setup, and decided to try the reamer (in a floating holder) anyway. My theory is that in a good concentric setup, the reamer will naturally try to center itself, also that the long Wby freebore in the reamer might help hold center. Must have worked, because with the Starret last word I measured .0007" on the belt cut ,worst case, and .0006" on the wall about an inch in, as far as I could reach.

This rifle is my own, and I unscrewed a good Hart barrel to try the Walther. I don't know enough about these barrels to put one on for anyone else, and I figured that the .30 x .378 on a Mk V action would be a good test for it.

Bottom line, quite a bit tougher to work than a 416 barrel, but if a mullet like myself can do it, a real 'smith would have no trouble at all. Now, to see if it will shoot well. I'm hoping for sub 1/2 moa, because I've seen it with Hart and Shilen barreled .30 x .378's.

This is long winded, but might help someone else thinking about using a Walther stainless barrel, with or without the Blackstar treatment.

Good shooting, Tom
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Last edited by specweldtom; 08-20-2008 at 05:02 PM.
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  #2  
Old 05-15-2008, 05:43 AM
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Just had an experince with a LW barrell and after ruining my reamer I junked it. POJ in my opinion. Give me a Broughton or Shilen or anything other than a LW.
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  #3  
Old 05-15-2008, 09:27 AM
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The Black Star barrels are great barrels , yes they are a bit more of a pain in the butt to machine but just as good of a job can be done with them as any other barrel.

For chambering I personaly feel that a reamer with replacable bushings is the best idea due to the slightly oversized bore and they have to be sharp. Here is a cut and past from their web site. I followed their instructions and had very little trouble the first time and none their after.

17-4PH is a FAR superior material for barrels and actions than 416 for strength but it has its down falls , its a bitch to machine compaired to 416 , it galls easly especialy if a 17-4 barrel is going to a 17-4 action. I personaly would like to see more action made from this stuff as its nearly twice as strong the action could be made a bit lighter

CHAMBERING OPERATIONS
There are two very important requirements to successfully chambering a barrel made from BlackStar steel: a sharp, concentric reamer with interchangeable pilots and the right cutting fluids.
The Reamer. Above all things, the chambering reamer must be very sharp. If there is even a small nick on one of the shoulder cutting edges, the reamer will feel as if it was dull. A build-up of material will occur at this point. In addition to being very sharp, the reamer must be concentric. An out of round reamer will cut as if it was dull, so check to see that one flute on the neck area is not doing most of the cutting. This is particularly true of the neck area. Last but not least, the reamer must have interchangeable pilots. Fixed-pilot reamers are not sufficient to machine this steel. Excessive space (>.0002") between the pilot and the bore will cause a very rough cut and will reduce tool life.
Today's steel chamber reamers are crafted from several different tool steels, depending on the maker. Carbide reamers continue to gain in popularity, and are suitable for chambering BlackStar steel with the right set-up. They are not, however, required to do a first-class job. If you have any questions concerning your particular reamer, please contact the reamer maker. All of the major reamer makers have positive experience with BlackStar steel, and can help you with any minor problems you might have.
Important Note. If you chamber using a fairly fast speed, you will build up heat on the edge of the reamer and prematurely dull it. Under these circumstances, the reamer may need a basic dressing every 5-10 chambers to maintain optimum performance. However, if you maintain a modest speed and feed, keep the barrel and reamer cool and well-lubed, your reamer should not wear significantly faster than it does cutting 416 stainless barrel steel.
Set-Up. To chamber with high-speed steel reamers, lathe RPM should be 50-90 RPM. Use whatever speed you are more comfortable within this range. In some respects, slower is better, so feel free to run around 50-65 RPM if that feels best to you. If you are using a carbide finishing reamer, you need to be aware that the best surface finishes are achieved at 230-300 RPM, according to Pacific Precision and many of the other reamer makers. Obviously, if you are using a carbide rougher, you can chamber at a much slower speed and clean up the surface with a HSS finishing reamer.
Regardless of the barrel steel type, chambering at low RPM with carbide reamers will not give you the same super-high-quality chamber surface that you can get with most high-speed steel reamers. Consequently, many of the reamer makers and gunsmiths that have worked with BlackStar barrels have stated that an ideal combination would be to use a carbide roughing reamer and a high-speed steel finishing reamer.
Set-up the barrel as you normally would. The rigidity of your set-up is always very important, but even more so with BlackStar barrels. Hold the reamer in a rigid manner relatively close to the flutes. (Make sure that the tail-stock is lined up exactly with the head-stock) A floating holder can be used. We encourage the use of a high-pressure muzzle flush system, as it will enhance the chambering of all steels, including 416R and 4140 chrome moly. However, the use of a muzzle flush system is not required to produce a top-quality job.
Reaming the Chamber. Apply a very liberal amount of lubricant to the reamer. Thinned high-pressure oil is an excellent option favored by many. Tap Magic for steel also will work or a thinned sulfurized cutting oil.
Several reamer makers and gunsmiths have reported that a mix of Rustlick high pressure mineral oil, thinned with Tap Magic and a little Moly D delivers optimum results with no appreciable wear on high speed steel reamers. Still other gunsmiths report using pure, undiluted Moly D with absolutely fantastic results. (Moly D is a high-pressure additive. Cost is about $50.00 per gallon, but really worth it.) Others have used a water soluble fluids with equally fine results. Clearly, there are a variety of cutting fluids that work well with BlackStar barrels.
When you begin, feed slowly and feel the reamer cut. Do not over-feed. If you are not using a muzzle flush system, consider the maximum tool advancement to be 0.100" between cleanings. For best results, advance only 0.025"-0.050" between cleanings. The degree of the advancement will vary from caliber to caliber. Above all, do not try to hurry the process.
When the reamer is removed from the chamber being cut, clean it completely. Make sure that there are no chips remaining on the bottom. Also swab the chamber and about 3" of the barrel in front of the chamber to make sure that there are not any hidden chips remaining. The last two cuts will be best if less than 0.030" deep.
If you are using a muzzle flush system with a high pressure pump, feed the reamer about 0.050" per minute, then wait 30 seconds for the reamer to cool and re-lube before proceeding with the next 0.050" of feed.

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  #4  
Old 05-15-2008, 04:15 PM
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Maico, when I first started to cut the chamber in this barrel, it looked like things were going the way that yours did. It had to get better or I wouldn't be able to use it. The advantage of being able to examine the chamber in detail with the Hawkeye as I made changes made all the difference. I hate to hear when one goes bad, I've been there.

Dave Manson bailed me out several years ago when a reamer chattered, and told me how I might save that barrel. It worked like magic and I've bought his reamers ever since. He will take the time to talk to you and if you leave a message, he will return it. If you get wadded up on a job again, you might call him. This particular reamer is a Clymer, but I wish it had been a Manson. He puts a different edge on his reamers in that he sharpens all the way to the cutting edge with one angle. My Clymers have a narrow edge ground on top of the flutes that doesn't have much rake. More like a scraper than a cutter? For these barrels, I would think that the Manson reamer would have an advantage.

James, if this barrel shoots good, I wouldn't hesitate to do another one. Just expect to take longer and to be a little tougher on tooling. Thanks for the info and the chambering instructions you included in your reply. I figured out a while back that I need to listen to anyone who routinely works in ten thousanths.

Tom
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  #5  
Old 05-15-2008, 08:28 PM
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Tom,
I use PTG floating pilot reamers and a muzzle flush system with a minereal spirits oil and auto tranny fluid as an additive as per Dave Kiff of PTG. The LW barrels cut like butter at 200-280 RPM with a floating reamer holder. There is no heat buildup and you can advance .100 to .125 per pass. Set up with a range rod, rough 2/3 deep with a drill, light boring cut to true at slight angle so that the shoulder of your reamer can enter the chamber and the pilot can enter the bore. I am using a Greymills 10 gal. cooling system w/1/6hp. pump, not even a high pressure system. If you plan to do any amount of work with these barrels this setup will save a lot of time, and you will appreciate these fine barrels much more.
Enjoy,
Randy
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  #6  
Old 05-16-2008, 10:08 PM
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Thanks Randy. Good info. I don't know if my nerves could stand chambering at 200 - 280 rpm with big reamers like the .378 based cartridges. Are your PTG reamers carbide?

I've got the stuff to build a continuous flush system except I haven't built a rotating muzzle gland yet. I need to take the time and do it.

Thanks again for sharing your expertise. However, until I see how this barrel shoots, I don't expect to cut any more of them. I hope that you and James are right though; I really like the 17-4 material's properties. Tom
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  #7  
Old 07-04-2008, 02:24 PM
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Bit late into the discussion, but ive chambered a few LW barrels.

All done via a through the spindle flush system, barrel spinning at 200rpm and piloted PTG reamers and bald eagle reamer holder.

Steel cut very well and finished chambers were concentric (2/10000 ths run out)

Rifles shoot in the .3's.

Would and am using LW again, very good barrels and excellent service.
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