300 Norma - Peterson Brass Problem

[jeffmedlin]

300 Norma and Peterson Brass - please help me with a problem I am not understanding.
I just picked up this rifle, bought it used with 76 rounds on it. I also bought the Peterson Brass and his Redding Type S Dies. But on the 2 times that I have taken it to the range, I have had problems chambering a few of the rounds. I will knock the bullet out, then get it to rechamber. I know he had several 300 Norma rifles, so I thought he had fired the brass in another "larger" chamber, and that is why it was having a hard time chambering, but now I don't think so.
My case length after resizing has been trimmed to 2.490. The case length using a E420 guage on the Hornady measures 2.068 to 2.069 in my chamber after firing... and when resizing I bump them back .002 to 2.066. But it will chamber some of them.... and some of them it will not. On the image shown below... I even bumped the shoulder back to 2.064 and the problem still occurs.
To eliminate further variables... I started to chamber empty cases, and the same problem is present. I have noticed on the cases that will not chamber is is leaving several scratches on the case neck, and also a really rough edge/scuff at the case/shoulder junction.
Hopefully the pictures will show you what I am talking about. The first image is a "fresh" unchambered round... then the following are images of a round that would not chamber, and I had to know out with a dowel.
So do you think its a problem with the Peterson Brass? Or a problem in the chamber?

Also...something that is even more odd... alittle update.... may or may not be helpful. But a round that will not chamber... i can knock it out with a wooden dowel. Then it may chamber 6 or 8 times in a row... then not chamber? Then it may not chamber 2 or 3 times... then chamber 5 t0 10 times in a row. Not consistent at all... and the same damn piece of brass!

 

[sandwarrior]

Problem in the chamber. As I hear it, this is new brass getting scratched up when chambering. I would tell whoever you bought this from to pass along to his gunsmith that cut that chamber, they need to go back to "Chambering a barrel 101"

The way you describe it, the chamber was out of round and from the pics there's crap in there that needed to be cleaned up with a finish reamer.

Before I go on and shove my foot further in my mouth (just in case I'm wrong), I assume you've cleaned this chamber? I've always liked to soak a chamber in bore foam then mop it out with a shotgun mop. All the hardened carbon comes out and if there are issues in the chamber, you should be able to see it.

 

[jeffmedlin]

Problem in the chamber. As I hear it, this is new brass getting scratched up when chambering. I would tell whoever you bought this from to pass along to his gunsmith that cut that chamber, they need to go back to "Chambering a barrel 101"

The way you describe it, the chamber was out of round and from the pics there's crap in there that needed to be cleaned up with a finish reamer.

Before I go on and shove my foot further in my mouth (just in case I'm wrong), I assume you've cleaned this chamber? I've always liked to soak a chamber in bore foam then mop it out with a shotgun mop. All the hardened carbon comes out and if there are issues in the chamber, you should be able to see it.

Yes the chamber is clean.... I have looked at it with a borescope. No Carbon.

Any idea why the same round, will not chamber.... knock it out, then it will chamber? Then chamber it several times just fine, then it will not chamber again?

It doesn't do it will all the brass.... about 10% of it or so.

 

[sandwarrior]

Yes the chamber is clean.... I have looked at it with a borescope. No Carbon.

Any idea why the same round, will not chamber.... knock it out, then it will chamber? Then chamber it several times just fine, then it will not chamber again?

It doesn't do it will all the brass.... about 10% of it or so.

Do you have a comparator that you can measure all the brass against each other? Individual scratches like what you show, say the chamber needs to be cleaned up (via lathe...not just cleaning).

 

[jeffmedlin]

Yes I do have a comparator... and the brass is measuring the same. Fired brass measures 2.068 to 2.069 out of the rifle... I have resized them to 2.0655 to 2.066.

So to clean up the chamber... would the barrel need to be pulled off the action I guess?

 

[Milo 2.5]

Yes the chamber is clean.... I have looked at it with a borescope. No Carbon.

Any idea why the same round, will not chamber.... knock it out, then it will chamber? Then chamber it several times just fine, then it will not chamber again?

It doesn't do it will all the brass.... about 10% of it or so.

If your borescope is worth a crap, with a Hawkeye, you should be able to place the tip 3/4 of the way up the shoulder and spin to view that area. I'm not sure if a Lyman has the resolution to do see this.

 

[sandwarrior]

Yes I do have a comparator... and the brass is measuring the same. Fired brass measures 2.068 to 2.069 out of the rifle... I have resized them to 2.0655 to 2.066.

So to clean up the chamber... would the barrel need to be pulled off the action I guess?

I would have to defer to a better gunsmith than myself. But, the issues you are describing, I would say eventually that's where you'll end up with this issue. It either cleans up with a light touch or you yank the barrel and cut a new chamber. It does sound to me your chamber is out of round.

 

[jeffmedlin]

Even the rounds that do chamber.... all of them are left with this scratch our gouge on extraction.....

 

[sandwarrior]

I'll say along with thinking the chamber is out of round, there is a burr left behind by the chamber reamer. That may be able to clean up with a light touch. The other option is a "new size" reamer that may be slightly larger than a production reamer that has been resharpened a number of times. The taper of the reamer is supposed to allow it to be sharpened back, but to full size. That's not always the case.

 

[Bradu]

Even the rounds that do chamber.... all of them are left with this scratch our gouge on extraction.....

View attachment 6995851

I would take the ejector out of the bolt to make sure that's not a scratch happening on ejection. I would think a burr in the chamber would leave a straight mark, not one like that.

 

[Namekagon]

Not sure if you resolved this yet, but...

I have a rifle that does this, only the scratch is at the base of the shoulder, on the case body. I can actually count the number of loadings I have on a piece of brass based on the number of scratches on the case. I discovered its a sharp edge on the inside rim of my ejection port (M700) that nicks the case on ejection. If I use pressure with my finger to prevent the round from ejecting or rubbing the action wall while slowly working the bolt, no scratch.

I have a hunch that, the reason a case will chamber 5 times, then not chamber, could be that it depends on how the case is rotated. Which would lead me to wonder if the brass was badly non-concentric.