Need some advice.

I reamed a complete .30-06 chamber this weekend using a brand new piloted PTG reamer. End result is the tightest chamber I've ever seen. Only real problem is that when I inspect the interior I see a few concentric lines. Just deep enough to barely catch on a probe. They look like they'd polish out, but I'd hate to induce any eccentricities doing that.

I used plenty of sulpherized cutting oil. Cleaned every .030". Feed rate was between .001" - .002" per sec. Speed 50 rpm.

Any hints, tips?

Thanks.

Rather than polish it out, cut it a bit deeper to clean up the scratches, and reset the headspace.

Zach,
If it was me, I would have cleaned the reamer more often near the end. I use a floating reamer holder on a quick change tool post holder, so it is much easier to back it out and clean. Mark Stratton, who taught the last chambering class ( and the one before for that matter) that I attended, said that was one of the advantages to using it in that manner. The ease of cleaning allows you the luxury of doing it more often. Clean it out as Terry said and adjust the shoulder and end of the barrel as necessary, or if necessary.

I'm assuming this is after using the finish reamer? If not, a couple of VERY LIGHT turns with the finish reamer may do the trick. (depending on how big the rings are)

Other than that, I would say polish the chamber by hand slowly. It will be almost impossible to induce any significant excentricities that way. (unless you get too crazy)

You know guys,

It just just be a poorly ground reamer. It might not matter how many times you cleared the chips. Lately I've bought new reamers from 2 different manufacturers that just sucked. One from JGS was a 6-fluted .300H&H finish reamer that cut with 1 1/2 flutes. If one or 2 flutes are cutting on one side of the pilot the cutter becomes a spoon cutter that applies a lot of pressure on the reamers pilot which rides on the rifling in the barrel. The surface finish of the chamber was rougher than a cobb. I sent it back 2 times and they told me that I was usuing the wrong lathe spindle speed. After the third time I threw the reamer in the scrap barrel and bought one from someone else.

Zach

I have been chambering barrels for several years now. Having worked in other shops I have observed several differant gunsmiths techniques. I also enjoy reading up on techniques used by some of the bench rest gunsmiths. I've watched them chamber at Shilen's facility too. And like Chic Worthing I have studied under Mark Stratton too. Mark is very talented and when he speaks I listen.

I have came to one conclusion. Gunsmiths being human will use slightly differant techniques to obtain the same results. Everyone has their own preferances such as chambering through the spindle versus between centers, slightly differant spindle speeds, feed rate, depth of cut before you clean the reamer and chamber, differant cutting oils or even using coolant throught the barrel. Brand of chamber reamer, brand of lathe, etc. etc. etc. What really matters is being a careful and knowledgeable workman/machinist. Having the desire to do first quality work and nothing less. Being well versed and well read on techniques. Trying the differant methods and using the one that produces the best result for you.

Having said all that I have a few methods to check out that I consider "a" way not "the" way.

The first time I ever used a PTG reamer I had problems, the reamer resisted any feed rate I tried and needed considerable torque to cut at all. I gave Dave Kiff a call and he asked what spindle speed I was using and I told him approximately 55 rpm. He explained that his reamers were made of a differant steel than everyone else's and required 80 to 110 rpm to cut correctly. If you use coolant throught the barrel you should use 150 rpm. Beleive me I was really pinching up when I ran the reamer in at 90 rpm but it cut beautifully just like Dave instructed. So its possible your rings may have come from too slow a spindle speed for that brand of reamer.

It has been hotly debated among well known riflesmiths but most have concluded that a light polish with 400 grit wet dry automotive paper on a wood dowel is acceptable. Shilen does this saying that the case needs a little cross hatch polish to help it grip the chamber wall during ignition.

What type of lathe are you using? How rigid is it? Is it level? Have you checked your set up to make sure everything was tight and rigid?

If it were me I would go over this check list, lightly polish the chamber and if the marks are still there I would set the barrel back and rechamber at 80 to 110 rpm.

Dont give up! If you persist you will find a way to correct the problem.

Thanks All!

I have an old 13" south bend that has surely seen better days but is still plenty rigid and tight where it needs to be. It's level too. I appreciate all the feedback.

Worst case I do like was suggested and cut a little deper and readjust headspace. But, I've determined that what I'll do is assemble it and try it as is. Not because I'm lazy but mostly as an experiment to see what affect the condition has. Then I figure I'll try polishing to see what difference I can note. If I am not satisfied then I'll rechamber and set back. It's mine and this is a learning experience so why not?

Shortly after I posted I called Dave Kiff and was also told that I was reaming at too slow a speed. I was at what I was told was 50 rpm but just got out of the shop and will be sitting down to recalculate the actual spindle speeds. This is an old overhead belt driven lathe. he suggested 120-160 rpm. I'll need to find out exactly which pulley is closest to that range. I know exactly which pulleys I need for all other cutting. Just need to figure out what works best for reaming. I have a couple of other chambers to cut so I will see what works best.

I am still amazed at how tight a chamber I cut. Thanks for the encouragement!