Real gunsmiths chime in.

[XP1K]

To the professionals out there, not the shade tree guys like myself, y'all tell me if I'm on the right track.

Some time ago I built myself my first rifle. Trued up my action to the best of my abilities and chambered my first barrel. It shoots pretty decent. Half moa is the norm with minimal load development, and it's shot a few in the. 3xx range.

The problem is, when I chambered it I got some reamer chatter toward the end of the chambering process, and I failed to notice it until I test fired it. It's very minimal, but you can feel it in the fired cases. And you can see it in the chamber now that it has a few hundred rounds on it. Probably more like 5-600.

But it shoots good so why mess with it? Well, #1 its not right, and it's bugged me since day one. And I think it's probably going to lead to erosion in the neck due to it not sealing like it should when fired. And #2, probably the main reason, I want to learn how to fix my mistake.

So here's where I'm at. Long ago, the smith that used to due my work for me, may he rest in peace, had told me he had one chatter one time. He had called brownells and was talking to them about it and they told him a process to follow to get it to clean up.

He said brownells told him to take a cotton/flannel cleaning patch and fold it in half and make a small cut with a pair of scissors in the middle, and to slide it over the reamer to the neck/shoulder junction and take a light cut. Repeat the process until it cleaned up. He said he only had to do it once. I forget the depth of cut he said he took.

So that's where I'm at. Am I headed down the right path ? What spindle speed should i run ? I'm here to learn, feel free to tell me if I'm screwing up or if there's another way I should go about it please let me know.

I already moved the shoulder, the breach face, and the bolt recess forward .062" and my witness mark on the barrel and reciever lined up perfect.

Also, I picked up a reamer stop off of LRH, and before I moved the shoulder and everything forward, I slid the reamer in and adjusted the stop to the breach face. Then I added .005" just to make sure I didn't go too deep.

Here's the setup.

 

[hlee]

I’m no gun smith. But, I’m a true believer in the adage of “if it ain’t broke, fix it until it is.”

 

[XP1K]

I’m no gun smith. But, I’m a true believer in the adage of “if it ain’t broke, fix it until it is.”

Fixing it won't make it shoot any worse.

 

[papershredder]

I'm no gunsmith. But having spent most of my adult life working in machine shops, sticking anything other than cutting oil between the tool and workpiece is dumb.

Here's some tips: Chatter is mostly caused by improper feeds & speeds and/or inadequate work piece & tool holding. Brand new, sharp tools are more prone to chatter if the above is not dialed in.

The amount of material you leave for the final cut will matter. Both too much or too little material can cause chatter. I'm not gonna go into detail explaining that, but make sure there is at least a good .005" - .010" worth of material for the reamer for a final cut.

You could try honing the reamer, but if you don't already have experience in doing that, then I don't recommend it. An alternative to honing would be to just obtain a junk or discount barrel and use it to practice a few times and the reamer will naturally dull up enough so it's less prone to chatter. Doing that will give you a chance to experiment with feeds & speeds and will let you know of any inadequacies in your set up.

Now all things said above is under the assumption that your lathe is up to task, solid foundation, no excessive vibrations from the motor or gears/pulleys, doesn't have a worn out spindle bearing, or worn out ways because any of those could also be a source of chatter.

 

[XP1K]

I'm no gunsmith. But having spent most of my adult life working in machine shops, sticking anything other than cutting oil between the tool and workpiece is dumb.

Here's some tips: Chatter is mostly caused by improper feeds & speeds and/or inadequate work piece & tool holding. Brand new, sharp tools are more prone to chatter if the above is not dialed in.

The amount of material you leave for the final cut will matter. Both too much or too little material can cause chatter. I'm not gonna go into detail explaining that, but make sure there is at least a good .005" - .010" worth of material for the reamer for a final cut.

You could try honing the reamer, but if you don't already have experience in doing that, then I don't recommend it. An alternative to honing would be to just obtain a junk or discount barrel and use it to practice a few times and the reamer will naturally dull up enough so it's less prone to chatter. Doing that will give you a chance to experiment with feeds & speeds and will let you know of any inadequacies in your set up.

Now all things said above is under the assumption that your lathe is up to task, solid foundation, no excessive vibrations from the motor or gears/pulleys, doesn't have a worn out spindle bearing, or worn out ways because any of those could also be a source of chatter.

Thanks for chiming in. Based on what you said above I'm going to say inadequate tool holding combined with the brand new reamer and my lack of experience is what got me the first time around. And quite possibly a machine that wasn't up to what I was asking of it.

This evening when I got home from work I went ahead with my original plan with the cleaning patch. Soaked everything in vipers venom cutting oil and made an .010" deep cut. You could feel the chatter in the reamer and then feel it smooth out as it cleaned up. I then stopped the machine pulled the reamer out and blew everything thing clean with air and inspected my work.

It looked to be going in the right direction so I repeated the process once more. This pass felt clean from the start. After that I took two more passes .020" at a time and finished with a final cut .003" deep. Final product came out nice.

Based on what you said about the depth of the final cut I will plan it out in the future where I have .005-.010" left at the end.

I assembled the rifle and test fired it and the brass was perfectly smooth now and the neck seems to have sealed off much better. As it should be.

 

[Smokin7s]

What is your machine? What speed were you chambering originally? Did you pre drill and bore the chamber before entering the reamer or did you raw dog it with a reamer all the way?

 

[XP1K]

What is your machine? What speed were you chambering originally? Did you pre drill and bore the chamber before entering the reamer or did you raw dog it with a reamer all the way?

The machine that originally chambered this barrel a a jet 1336PBD. Late 80's Taiwanese bench top machine. Fairly heavy for what it was. It built a lot of good rifles before I got it.

I sold that machine to buy my current lathe. This one is a profit master. Made in Brazil. 14x60. Knew the previous owner. It built three of my own rifles before I owned it. This it the first chambering job I've done on it. I did make a short dry run on an old barrel stub before I went ahead with this one.

Originally I chambered the barrel at 60 rpm. The slowest the jet would go. This time I touched up the chamber at 63 rpm. 2nd gear. 1st gear on this one is 40. The next option would be 100. Or faster if you prefer.

I did not pre drill and bore the chamber. There seems to be varying opinions on this. Some do, some don't. Out of the three people I know personally, or knew, that do this kind of work, none of them pre bored, and only one had an issue one time that I know of. I go slow and take it easy. About .025-.030 per cut. It's time consuming, but many do it this way and it seems to work. One of these days I'll build a pressure flush system. This lathe has a built in pump but it's not working currently. I need to dig in to that.

I'm fairly certain what got me the first time around was my reamer holding setup. I built a rigid holder out of a mt2 tailstock blank and I don't believe the little jet was up to the task. This time I used a bald eagle floating holder.

 

[Ledzep]

The patch on the reamer will clean up the chatter.

 

[MikeMiller]

Not a real smith but thanks for sharing. I have been wanting a lathe to do my own barrel work and your info helps

 

[XP1K]

Not a real smith but thanks for sharing. I have been wanting a lathe to do my own barrel work and your info helps

Glad you found value in it. Whatever you do, don't get into doing your own work thinking it's going to save you money. It is a fun learning process though if you enjoy that sort of stuff.

And after having a lathe you wonder how you ever got along without one.

 

[MikeMiller]

I appreciate it. Only reason is I hate waiting. Once many pistol smiths got three years wait for work I started doing more smithing on my own. Been an armorer since mid 1990’s but until five years ago avoided any cutting of metal. Now I do what I can with files and drill press. Want lathe and mil to do more. Won’t save a dime but will have pride I did it. Will still send my top stuff to great smiths because that level is only obtained through tons of work

 

[XP1K]

I appreciate it. Only reason is I hate waiting. Once many pistol smiths got three years wait for work I started doing more smithing on my own. Been an armorer since mid 1990’s but until five years ago avoided any cutting of metal. Now I do what I can with files and drill press. Want lathe and mil to do more. Won’t save a dime but will have pride I did it. Will still send my top stuff to great smiths because that level is only obtained through tons of work

A mill is next on my list. I was doing some milling in my lathe the other day, but it's a lot of setup and it's not ideal. Would be much faster in a mill.

 

[Mulepackhunter]

Yes the patch or cheap paper towell helps with chatter but it will also be cutting so dont forget headspace after fixing. Really good cutting oil helps as well, High sulphur content.

 

[Mulepackhunter]

Old tapped hole trick, paper towel in a tapped hole re run tap and get oversized threads.

 

[Smokin7s]

The machine that originally chambered this barrel a a jet 1336PBD. Late 80's Taiwanese bench top machine. Fairly heavy for what it was. It built a lot of good rifles before I got it.

I sold that machine to buy my current lathe. This one is a profit master. Made in Brazil. 14x60. Knew the previous owner. It built three of my own rifles before I owned it. This it the first chambering job I've done on it. I did make a short dry run on an old barrel stub before I went ahead with this one.

Originally I chambered the barrel at 60 rpm. The slowest the jet would go. This time I touched up the chamber at 63 rpm. 2nd gear. 1st gear on this one is 40. The next option would be 100. Or faster if you prefer.

I did not pre drill and bore the chamber. There seems to be varying opinions on this. Some do, some don't. Out of the three people I know personally, or knew, that do this kind of work, none of them pre bored, and only one had an issue one time that I know of. I go slow and take it easy. About .025-.030 per cut. It's time consuming, but many do it this way and it seems to work. One of these days I'll build a pressure flush system. This lathe has a built in pump but it's not working currently. I need to dig in to that.

I'm fairly certain what got me the first time around was my reamer holding setup. I built a rigid holder out of a mt2 tailstock blank and I don't believe the little jet was up to the task. This time I used a bald eagle floating holder.

Pre drill your chamber and bore it till it’s .010 ish under smallest diameter of reamer and I bet you never have chatter again. Plus your reamer will start into a hole that’s been single point cut thus making sure that your bore is concentric at least to the spindle, and if you did your job also to the indicated point in the barrel. If I start a reamer and it chatters at all I’ll pull it out and take a few more thousands with the boring bar and it cleans right up. I’d do that before I put a patch or papertowel in. I also buy rigid dark by the 5 gallon bucket and use it like it’s free. You’re asking a lot of your reamer to basically run as a drill through 416r stainless when a good set of bits can be bought for 100 dollars and if you wear one of those out just go a size down and bore more.

 

[XP1K]

Pre drill your chamber and bore it till it’s .010 ish under smallest diameter of reamer and I bet you never have chatter again. Plus your reamer will start into a hole that’s been single point cut thus making sure that your bore is concentric at least to the spindle, and if you did your job also to the indicated point in the barrel. If I start a reamer and it chatters at all I’ll pull it out and take a few more thousands with the boring bar and it cleans right up. I’d do that before I put a patch or papertowel in. I also buy rigid dark by the 5 gallon bucket and use it like it’s free. You’re asking a lot of your reamer to basically run as a drill through 416r stainless when a good set of bits can be bought for 100 dollars and if you wear one of those out just go a size down and bore more.

I might give it a shot on my next one. I'm always down to learn a better way to do things.

 

[Smokin7s]

I might give it a shot on my next one. I'm always down to learn a better way to do things.

The fella that trained me went full reamer I learned pretty quick it wasn’t for me

 

[XP1K]

The fella that trained me went full reamer I learned pretty quick it wasn’t for me

Question on pre drilling. Do you go just deep enough that the pilot will still engage the bore, or do you not worry about the pilot?

I've always been told a reamer will naturally follow the center of whatever hole it's started in. As long as there are no opposing forces pushing it off center. If that's the case, why is there a pilot in the first place ?

Speedy Gonzales removes the pilots from his reamers when chambering.

 

[papershredder]

Question on pre drilling. Do you go just deep enough that the pilot will still engage the bore, or do you not worry about the pilot?

I've always been told a reamer will naturally follow the center of whatever hole it's started in. As long as there are no opposing forces pushing it off center. If that's the case, why is there a pilot in the first place ?

Speedy Gonzales removes the pilots from his reamers when chambering.

The pilot is just there for a guide. Yes a reamer will try to follow the hole even without the guide. Regardless if you use the pilot or not, using a stationary holder that's not truly lined up with the work piece, you might end up with a finish that is oversize, not concentric, chatter, etc. A lot of gunsmiths opt to use floating holders for their reamers to mitigate that. But floating holders come with their own set of quirks as well, they're a solution for some, but not an end all solution.