What's in the chamber?

[butchlambert]

Thanks for helping him. So the runout he was speaking of was the OD of the barrel to the bore center. That is about as close as you will find on a barrel and means nothing. I'm glad he is fixed up and probably learned something.
Butch

 

[LR_Shooter]

I guess I missed something if it means nothing, its all new to me...

 

[butchlambert]

I'm always willing to learn. What does .004 runout of the OD of the barrel to the bore centerline have to do with anything?
Butch

 

[Preacher]

No it really don't mean much, and has nothing to do with accuracy, but 99% of the Brux and Pac-Nors I use are a heck of a lot closer to center than that Savage was.

 

[DanCarey]

I hate to sound uninformed but I don't check the barrel for that particular dimension, I always figured it was one of those non critical dimensions, kinda like length of the barrel.

How ya doing PaPa?

 

[butchlambert]

Doing great Dan and hope you are also. Did you move to AZ?
Butch

 

[Preacher]

The only reason I check it is it helps me get closer to the center, quicker.
I dial in the outer to get close, and then to a tapered rod to get even closer, and then to the .0001 dial
for the final tweaking..
It's just the way I do it, is all it amounts to..

 

[sailhertoo]

1. The person who chambered the barrel most likly stopped the lathe from turing before removing the reamer. The leading edge of one of the reamer flutes cut the scratches in the chamber. I have personally experienced this myself.

2. For those who use a floating reamer holder. If you use a improperly fitted bushing the reamer will cut ridges and valleys linerally the length of the case from the shoulder to the web area.

Nat Lambeth

I always thought it was better to pull the reamer out after the lathe stopped to prevent rolling a metal chip over the top of the reamer cutter and scarring the chamber. You thinks that not right?

 

[shortgrass]

All cutting tools are about Surface Feet Per Minute (SFM). If run too fast for the material being cut they don't do a good job and wear out prematurely. If run too slow the tools chip on the cutting edges, hence, the 'ridges' on the shoulder.

 

[sailhertoo]

I understand what your saying but what does that have to do with stopping or not stopping the lathe before you pull the reamer out?

Maybe 'ol Rustystud will chime back in.

 

[shortgrass]

If you stop a machine, any machine, with the cutting tool engaged SFM is lowered until not existent as the machine coasts to a stop. Low SFM can and will 'chip' cutting edges.

 

[butchlambert]

AS mentioned above, I stop the spindle before I pull the reamer out. Maybe Rusty Stud's blow through coolant blows out the swarf and keeps him from having a problem.
Butch

 

[Rustystud]

There are several things that can affect the finish of a chamber. 1. The actual shape and surface of the reamer. 2. Distortions created by swarf and chip weld. 3. Approach direction and concentricity of the reamer to the bore. 4. Reamers not cutting evenly on all flutes. 5. Chatter or harmonics.

Reamers are usually guided into the barrel one of two ways: 1. Piloted by the bushing. 2. Aligned by the pre bore and the taper of the reamer.

Chambers reamed using a floating reamer holder or loose reamer shank can and will follow the path of least resistence. I have seen chambers where the reamed using the bushing on one end and a floating reamer holder where the reamer pitched and/or yawled during the chambering process. This can cause the chamber to be out of round or egg shaped. I have seen chambers with multiple ridges and valleys length wise in the chamber. These ridges and valleys are very pronounced on a fired case. This phenomina I beleive is caused by a harmonic response of the reamer floating the riflings and not being guided by the bushing. I have twice seen this with two different reamers that have cut many great chambers in other barrels.

With using a high pressure flush system and high speed reaming. Problems when they develope, develope faster and usually are more exagerated than when a chamer is reamed slowly.
Nat Lambeth

 

[LR_Shooter]

Rustystud, ridges and valleys, exactly that's what I had in my factory chamber: