Getting nicks on the rims brass

[cactus joe]

I just recently bought a marlin '94 made in the mid 1920s in .38-40. The gun is extraction and ejecting with no problems, but my brass gets a nick right on the edge of the rim about the width of the extractor or ejector. These are reloads. the nick is easily seen and felt one each case. I have fired about 100 rounds through the gun. Before reloading each case i take a small file and touch up the rim. The problem is not causing any functioning problems i'd just like to know why it's happening. It almost seems like my extractor is setting on the outside edge of the rim as opposed hooked on the rim and when the gun is fired because of the recoil it then hooks over the rim, but somehow it's marking the rim up. Or when i'm working the lever the ejector is somehow marking the rim. Any ideas of what might be causing this?

[cactus joe]

ok i might have figured my problem out. The brass i bought from a bin in a gun shop seems to be over expanded. I compared it to some new brass that i just received and the old stuff's shoulder seems to be set back and the brass is expended more. I think this has effected the chambering of my rounds. Which might explain why the extractor is setting on the case rim when i close the action. I did resize the brass each time i loaded it, but it still did not bring it back to size of the new brass. I'll load up some of the new brass and see if my problem is corrected. I could be wrong but i think that this my problem.

[Abilene]

I know nothing of Marlins, so am just standing by, but keep us informed.  Good luck.

[cactus joe]

Thanks. Today im going to load up a few rounds of the new brass. If it goes well those 50 old ones are going into my trash brass bin!

[Coffinmaker]

  Cactus Joe 

Very probable the problem ain't your brass.  Your reloading dies are going to size the brass to "a standard" no matter what the brass was sized to before.  I do expect you are re-sizeing this brass before you load it.

The behavior of your rifle would lead me to believe you have a Head Space issue.  The extractor may well be what is seating the brass in the chamber and then when fired the brass "sets back" against the face of the breach block which sets the hook for extraction.

Also, you may well find the chamber dimensions may well not match the dimensions your resizing die is resizing too.  Often the case with the dash calibers.  You may wish to do/have a chamber casting done and compare that to your cases.

Most important . . . .  when reloading dash calibers, it is very important to hold yer tongue just right.  Murphy ya know.

[cactus joe]

Thanks coffinmaker, Yeah i did think about a headspacing problem. You might be right. Fixing that is gonna be costly. I'll try the new brass and see how that goes 1st.