Chambering woes

[Kurt.A]

Hi All,
Looking for advice on chambering a 22LR barrel. I purchased a new chambering die from Brownells. According to the sales info they advised that if you are only planning on chambering a few barrels that the finish die is all that is needed. Otherwise use a roughing die then the finishing die.
I have made 3 attempts at chambering now and all 3 have a beautiful finish on them however they are all oversize from the SAAMI specs of .230". The chamber reamer measures .230". The best result so far is a bore of .237". After the first attempt resulting in a chamber bore of .239" I went completely through my lathe tune up and dialed it in to the best I have ever seen it. I have also gone through the Tailpost and tuned it to perfection. After the second failure to produce the desired result I checked to see if the bore of the barrel was centered when chucked up. Using the pilot of the chamber reamer in the barrel bore I found that the bore had a runout of .0035. I shimed between the chuck and the barrel to get the run out to be .0005". This resulted in the .237" bore. I am using a Lathe RPM of 24 RPM with Rapid tap cutting oil. I advance the chamber reamer .100" per cut then clean the cuttings and re-oil. I am also cutting with as little force as possible applied by the tailstock. The tailstock handle is heavy enough to advance the cut.
Hopefully someone can steer me in the right direction.

 

[MilGunsmith]

You need to center the bore and not the OD, it also must be parallel to the centerline of the lathe.. Use a tight fitting gage pin, grizzly rod, or a long stem indicator. There are multiple methods based upon your equipment and skills. How are you holding the chambering reamer?

 

[akajun]

Are you chambering in the headstock or between centers? If through the headstock are you using an outboard spider or a viper fixture. Make sure your using a floating pusher to hold the reamer, if not it will make an oversize and often tapered bore. The reamer needs to follow the bore. Also just double check the reamer make sure its not oversize itself.
The part of the bore you want to indicate is where the throat will be and 1.5 to two inches ahead of the bore or where the throat will be and the muzzle (yes I know there are differing schools of thought on this, were just trying to get him no cutting oversize). You have to indicate in two places on the bore.
And dont use shims to adjust, thats what you do with a 3 jaw. Use a four jaw or a cathead if you use a chuck.

 

[Kurt.A]

You need to center the bore and not the OD, it also must be parallel to the centerline of the lathe.. Use a tight fitting gage pin, grizzly rod, or a long stem indicator. There are multiple methods based upon your equipment and skills. How are you holding the chambering reamer?

No gauge pins to work with so I used the chambering reamer pushed into the bore up to the throat cutting portion of the reamer. I dialed in on the shank of the reamer to get centered and parallel. I have been holding the reamer with a drill chuck mounted in the tailstock. After saying that I wonder if the drill chuck jaws are the source of my woes????

 

[Kurt.A]

Are you chambering in the headstock or between centers? If through the headstock are you using an outboard spider or a viper fixture. Make sure your using a floating pusher to hold the reamer, if not it will make an oversize and often tapered bore. The reamer needs to follow the bore. Also just double check the reamer make sure its not oversize itself.
The part of the bore you want to indicate is where the throat will be and 1.5 to two inches ahead of the bore or where the throat will be and the muzzle (yes I know there are differing schools of thought on this, were just trying to get him no cutting oversize). You have to indicate in two places on the bore.
And dont use shims to adjust, thats what you do with a 3 jaw. Use a four jaw or a cathead if you use a chuck.

Chambering using the headstock with a 3 jaw chuck and tailstock. I have checked the reamer diameter, it measures .2305" and should be .230". Sorry no tooling to check that deep into the bore directly.

 

[jim rozen]

...Make sure your using a floating pusher to hold the reamer, if not it will make an oversize and often tapered bore.....

This. You need to re-read this part here. The jacobs chuck in the tailstock does not qualify as 'floating.'

 

[michiganbuck]

QT: [it measures .2305"]..So should cut .2307 if all is right with the tool.]

But reamers are very hard to measure. I used to finish grind high precision reamers and if your flutes are not exactly straight across the measurer may be invalid. Plus the end my have a high tooth and that can make a reamer cut a little big. Best to run a sample in a similar material for a test run and look at the end teeth with a loop to see all flutes are cutting.

One trick I used to make the best cutting reamers was to backspin the last few tenths. That is spinning so the heal contacts the wheel first..and the roll-off is to the lead edge.

QT Op: [I shimed between the chuck and the barrel to get the run out to be .0005". ] if the chuck has wobble the .0005 may still not be very good.

I am not a gunsmith but have put the muzzle end in a 4jaw to zero and then put the chamber end that was held in place by being on the tail center, in a steady rest for barrel turning, if this runs/checks true might be Ok good for chambering.

 

[72bwhite]

Do it between centers.
If you were using a 3 jaw ain’t going to happen
If you did the tenon in the 3 jaw it needs redone as well

For a novice centers is probably the easiest way

Not sure how you are measuring the chamber size with out gage pins

 

[akajun]

Chambering using the headstock with a 3 jaw chuck and tailstock. I have checked the reamer diameter, it measures .2305" and should be .230". Sorry no tooling to check that deep into the bore directly.

Ok well your just not tooled up enough to chamber through the headstock. At the minimum you need a test indicator, preferably with a long stem to reach in the bore. Your gonna need to make a reamer holder/pusher and some gauge pins if you dont buy them. Your also gonna need a 4 jaw or a cathead plus a outboard spider, or make or buy a viper fixture or tru bore system.

Either that or chamber between centers using a steady.

Buy John L Hinants book on chambering, will get you started with either method.

 

[Hbjj]

I'm by no means a pro or even a gunsmith but a few key things I've learned in my quest for 22lr accuracy are.

slug the barrel and make shure the small spot is the muzzle.

The inch of barrel just after the chamber must run perfectly true to the chamber.

The finish on the leade is critical so much so that the techniques used to produce it are closely guarded secrets!

If you're not interested in maximum accuracy then you're .237 chamber would probably work ok but if you want more than factory level accuracy I kindly suggest more research is needed

.22lr is a frustrating thing to make accurate it's very different from center fire.

 

[Paolo_MD]

Do it between centers.
If you were using a 3 jaw ain’t going to happen
If you did the tenon in the 3 jaw it needs redone as well

For a novice centers is probably the easiest way

Not sure how you are measuring the chamber size with out gage pins

I admit not being a professional and having somehow limited experience. I am rather puzzled about being able to access the bore when the barrel is held between centers.
Could you, please, explain how would you set it up?

Paolo

 

[tdmidget]

I realize that you have little if any experience with this but you bare making it much more difficult than necessary. You are removing only a tiny bit of metal when done properly and you are removing twice as much as necessary. Hopefully the pilot on your cutter is a very close fit to your barrel. If not then that needs to be corrected. If so put the barrel vertically in a vise and start the cutter pilot in position. Turn it with a tap wrench. As you have discovered the amount removed is so little that the tailstock quill handle would advance it by the crank weight. Oil it up and turn with the tap wrench, let the weight of the wrench advance it. If your pilot is the proper fit you will be done before you can read half the replies.
Search this site ( with Google, the search feature sucks) for "chambering between centers and Speerchucker". He tells how in plain english, no BS. I miss that guy.

 

[michiganbuck]

https://www.shootingtimes.com/editorial/accuracy-and-the-22-long-rifle/326553

I am not a gunsmith but have put the muzzle end in a 4jaw to zero and then put the chamber end that was held in place by being on the tail center, in a steady rest for barrel turning, if this runs/checks true might be Ok good for chambering.

With this method I would use the tail to locate the barrel for the steady, then when in position back the tail away...Yes, this was for barrel OD turning 98s.. likely could have used this method for chambering but I was not chambering them.

My thought was to maintain very close OD to Id in order to better hold accuracy at the barrel warmed up.

I was customizing military Mauser 98s at that time.

 

[Kurt.A]

Thanks for all the responses. Looks like I will be fabing up a floating reamer holder before carrying on with this project.

 

[Paolo_MD]

I realize that you have little if any experience with this but you bare making it much more difficult than necessary. You are removing only a tiny bit of metal when done properly and you are removing twice as much as necessary. Hopefully the pilot on your cutter is a very close fit to your barrel. If not then that needs to be corrected. If so put the barrel vertically in a vise and start the cutter pilot in position. Turn it with a tap wrench. As you have discovered the amount removed is so little that the tailstock quill handle would advance it by the crank weight. Oil it up and turn with the tap wrench, let the weight of the wrench advance it. If your pilot is the proper fit you will be done before you can read half the replies.
Search this site ( with Google, the search feature sucks) for "chambering between centers and Speerchucker". He tells how in plain english, no BS. I miss that guy.

I think you're referring to this thread. I admit, I am probably a bit anal, but I like to use proper terminology: the barrel is held at the muzzle side in a 4-jaw chuck and at the breach side on the threads with a steady rest. No centers at all involved in that operation, although the barrel must be machined between centers when cutting the threads (or, even better, you can screw on a "thread protector and machine it between centers while mounted on the barrel to give the steady rest a proper bearing surface) in order to be sure you are cutting the chamber straight and in axis.

I second the suggestion of hand-reaming the chamber. When close to finish, if the reamer tends to "sing", it works great wrapping a layer of light tissue paper (or even toilet paper) around the reamer before the final cut: the cutting edges of the reamer cut easily through the paper but the tissue stays in place reducing the relive angle and dumpers the vibrations.
Be careful that you have also much reduced room for the chips to go. This is the reason this technique should be used only for the final touch-up to remove possible chatter marks.

Paolo

 

[akajun]

You use the existing centers drilled on each end of the barrel. You place each end between centers and figure out where you want your steady rest to sit. Then you either turn a small section of the barrel to run true with the ID so the steady rest fingers can ride or build a small cathead or expoxy a piece of scrap to make a bushing and turn that true for the steady to ride on. Some people will turn down the area where the threading will take place to run true, chamber, then put it back between centers and thread. Others will turn a small flat at the barrel shoulder which kind of blends into the taper before it starts.
Seriously, get the John Hinant book

 

[michiganbuck]

You might turn dowel/rod with a very slight taper to fit the bore and snug up..so to be used as a gauge to check your set-up for wobble.

 

[Hbjj]

Thanks for all the responses. Looks like I will be fabing up a floating reamer holder before carrying on with this project.

I've had bad luck with shop made (floating reamer holders).

The problem seems to be that I'm removing about .006 is all and on the barrels I'm messing with there are 4 lands and my reamer is 4 flutes so it sorta pulses in the cut making a slightly tapering and oversized chamber. About .001 over my reamer.

On my next try I'm using a solid reamer holder I made that is adjustable so I can dial it in exactly on spindle center line.

But I'm interested in a better floating holder please share what you build!

 

[Hbjj]

Barrel chambering

Some of the top rimfire benchrest smith's talking chambering most is well above me but it's good info anyways

 

[Ian Robertson]

Hi All,
Looking for advice on chambering a 22LR barrel. I purchased a new chambering die from Brownells. According to the sales info they advised that if you are only planning on chambering a few barrels that the finish die is all that is needed. Otherwise use a roughing die then the finishing die.
I have made 3 attempts at chambering now and all 3 have a beautiful finish on them however they are all oversize from the SAAMI specs of .230". The chamber reamer measures .230". The best result so far is a bore of .237". After the first attempt resulting in a chamber bore of .239" I went completely through my lathe tune up and dialed it in to the best I have ever seen it. I have also gone through the Tailpost and tuned it to perfection. After the second failure to produce the desired result I checked to see if the bore of the barrel was centered when chucked up. Using the pilot of the chamber reamer in the barrel bore I found that the bore had a runout of .0035. I shimed between the chuck and the barrel to get the run out to be .0005". This resulted in the .237" bore. I am using a Lathe RPM of 24 RPM with Rapid tap cutting oil. I advance the chamber reamer .100" per cut then clean the cuttings and re-oil. I am also cutting with as little force as possible applied by the tailstock. The tailstock handle is heavy enough to advance the cut.
Hopefully someone can steer me in the right direction.

If your reamer is from Pacific tool you will not know if it matches the print.