Oval Chamber? Crooked Chamber?

[INTJ]

I used to think a chamber could be cut crooked. I have very recently seen someone talk about an oval chamber. However, since I have had my lathe I don't see how a chamber could be crooked or oval. I chamber through the headstock with a floating reamer holder in a PM 1340 GT lathe.

I can see how a chamber can be oversized and I see how a chamber can be scratched--I have done both of those things. But how do you make an oval or crooked chamber?

 

[Adam in WI]

Rotate a reamer with a wandering axis into a stationary barrel?

 

[Dusty Stevens]

Dull or badly sharpened reamer

 

[INTJ]

Dull or badly sharpened reamer

How would that cause an oval or crooked chamber? It would certainly make a poorly finished chamber.

 

[Stan Taylor]

I won't comment.

 

[Rustytigwire]

2 flute twist drill makes a triangle hole with a hand drill in steel if you watch.

 

[INTJ]

I won't comment.

Please do, unless making oval and crooked chambers is a secret of top gunsmiths....

 

[INTJ]

2 flute twist drill makes a triangle hole with a hand drill in steel if you watch.

Yes, drills do wander. But a piloted reamer?

 

[Dusty Stevens]

Yes, drills do wander. But a piloted reamer?

Put a reamer base in a vise, setup a dial indicator on the body somewhere, and just push on the reamer to check deflection. A reamer follows the bore no matter how fast or light you feed it, and if you deflect the pilot area the lower body sometimes goes the other way. This is how a reamer can make an oval hole and the way you hold the reamer can influence it no matter how much it “floats”. Lathe condition and rigidity also comes into play.

Heres a guy drilling a square hole. Notice his “floating” drill holder.

 

[butchlambert]

Can't say it doesn't happen but I see a chamber with a larger diameter base and not egg shaped.

 

[Stan Taylor]

Can't say it doesn't happen but I see a chamber with a larger diameter base and not egg shaped.

Butch
I commented earlier that I won't say anything, about this question.
I have seen a egg shape chamber one time that a customer had done an complaining about busting brass he sent the barrel back to us to inspect, we didn't do chamber job he did we ask him after inspection how in the world did this happen we give him benefit of the doubt had him send his action an we replace the barrel.
Liabilities reason we fit his action some folks have no business chambering barrels in other words normal chamber process shouldn't egg shape a chamber.
Here is a pic of a 30/06 chamber job that customer said we screwed up on a 1903 Springfield.
Low an behold we ask this customer to send his Springfield 1903 an we installed this barrel also an never charged him fitting services also .

 

[tobnpr]

Sloppy fitting pilot.
Bore that is not correctly dialed in. Dialing in a single spot to zero runout doesn't mean it's in axial alignment.

 

[Bamban]

Talk about people who should not doing barrel work.

Back when I was chasing the best M1 gunsmith/builder in the country for 1000 yard shooting, this guy was recommended to me. So I sent my leftover Hart barrel from benchrest hunter days (yup, we shot full blown 308s back in the day)

While the rifle shot OK, it scared me to death when I fired it. The 308 bras came out looking like belted case. I sent the rifle to the late Don McCoy, he fitted an Obermeyer, and did his tricks of the trade to the old battle rifle, and I could not be happier.

Here is a picture comparing the breech to another barrel. You can look deeper in ther you will see how much (less) is the web supported. Looks like the builder had issues that he never mentioned, see leftover red loctite

 

[Stan Taylor]

Bamban
After looking at pics might be wrong but the one with more case sticking out looks like this one but it's short chambered by .025 thousands.

 

[Bamban]

Bamban
After looking at pics might be wrong but the one with more case sticking out looks like this one but it's short chambered by .025 thousands.View attachment 1164914

That was the final config, it closed nicely on a 1.632. The counterbore was cut way too deep. I should have saved the fired case, it was scary, the brass being the weakest part in the system.

 

[INTJ]

Thanks for all the comments. There will always be a lot more about chambering that I don't know than I do. My last two chamberings went well and both rifles are shooting well. I don't think either chamber is oval or crooked.......

 

[ridgeway]

Thanks for all the comments. There will always be a lot more about chambering that I don't know than I do. My last two chamberings went well and both rifles are shooting well. I don't think either chamber is oval or crooked.......

Trust your indicator in the end result.

 

[rgc54]

After your chamber is reamed check the run out of the neck,,shoulder,,and the base. Those readings will tell you how good your setup is. They should be the same as your spindle bearing runout.

 

[LVLAaron]

Dull or badly sharpened reamer

Would say, a PTG reamer that always picked up chips on one flute do this? - I just did a 6 dasher (First time doing a 5R barrel) and the body came out egg shaped. Less than a thou of runout but it is shaped like an egg. Neck and throat area indicate true. Machine and other reamers chamber without problem.

I flipped the reamer and holder over 180 degrees at one point and the same flute picked up all the chips on the other side. Shoulder/neck area seemed to cut evenly.. just a problem with the body.

I'll put the reamer in a vice tomorrow and run an indicator around it to see, but my mind was wandering before bed and found this thread.

 

[Bamban]

Would say, a PTG reamer that always picked up chips on one flute do this? - I just did a 6 dasher (First time doing a 5R barrel) and the body came out egg shaped. Less than a thou of runout but it is shaped like an egg. Neck and throat area indicate true. Machine and other reamers chamber without problem.

I flipped the reamer and holder over 180 degrees at one point and the same flute picked up all the chips on the other side. Shoulder/neck area seemed to cut evenly.. just a problem with the body.

I'll put the reamer in a vice tomorrow and run an indicator around it to see, but my mind was wandering before bed and found this thread.

Here is rookie head scratcher. I am having a hard time visualizing, even only cutting on one flute against a rotating barrel, on how it will produce egg shape hole. I can see oversized, but not egg shaped.

Please enlighten.