180gr bullets hitting something in chamber???

[Hooter]

Hi everyone,

I have noticed something very peculiar with my rifle and I need your help. I have been reloading my own bullets for my Sako Finnlight 75 .300 Win Mag for about 6 years now, but lately I've noticed something that has me concerned. Ever since I changed from loading 165gr Nosler Paritions to loading 180gr Nosler Partitions it seems that if the same shell is cycled in and out of the chamber enough times that eventually there is a specific orientation that causes the side of the bullet to contact something in the chamber or barrel of my rifle and it "scuffs" the bullet. If I simply rotate the shell a tiny bit it will no longer hit anything and the bolt closes smoothly and easily as it should.

I've tried seating the 180gr bullet at various depths with the help of my RCBS Micrometer Set to resolve this issue, but this weekend I noticed that it's not the ogive that is hitting (which is what the micrometer measures), but rather farther back on the bullet not too far in front of the top of the casing (maybe 3/16") where the bullet is pretty much flat on the side.

I have made sure that the casing isn't hitting, and I never had this problem with 165gr Nosler Partitions which were seated much farther out of the shell such that they were only 0.010" off the lands. I am now about 0.050" off the lands and having this "contact" issue, so I'm certain it's not the bullet contacting the lands of the barrel but rather something else in the chamber/barrel.

Any advise or insight would be greatly appreicated.

-Trevor

[leo]

Is this the only lot # of 180's that you have tried ? They may have a inconcentric radius or some out of true anomaly .I would try another batch with a different lot # to see if they give any trouble.

[7RUM]

you might want to get a concentricity guage to make sure the bullet is true to the case.

[Dick284]

It most likely is the ejector is pushing the case and the bullet in the direction it will eject, and it is rubbing against the side of the chamber and the receiver wall as it is withdrawn.

This is not uncomon with plunger style ejectors.

[Hooter]

Originally Posted by leo

Is this the only lot # of 180's that you have tried ? They may have a inconcentric radius or some out of true anomaly .I would try another batch with a different lot # to see if they give any trouble.

I have tried 3 different lot numbers, all with the same result, so that's how I narrowed it down to being the rifle and not the bullets.

Where do I buy a gauge to test the concentricity of the bullets?

Thanks for the advise so far!

-Trevor