Went to the range a while back to test my new 91/30.  After each round fired, the bolt would stick and I had to use a little force to unlock bolt to extract spent brass.  Asked an armorer friend and he said that it sounded as if the chamber may have some cosmoline build up.  He stated to use a brass cleaning brush and paint thinner to scrub the chamber, but don't get carried away the the thinner.  

Only fired 9 rounds.  4 of the spent brass appeared to have a scratch less than an inch long.  (If that means anything.)  

Should have asked this much sooner but sometimes I put things off.  Thanks in advance.

What ammo were you using?  

You could have a burr in your chamber causing the scratch
and/or the cosmoline and lacquer on the cases is causing it.

As far as a fix sticky bolt syndrome, try this:
Get a 20ga. brush, drill, solvent, and a cleaning rod section

http://www.surplusrifle.com/shooting2005/eliminatesbs/index.asp

Ammo- Now that is a good question.  Split a can with my brother.  Russian light ball from Aim.  Box is white with no markings.  Cartridge is copper color.  

Burr in chamber is what I was thinking also.  My friend said to use a .45 cal brush but same instructions as yours.  Thanks.  

Common.  Almost normal.  Usually rough/dirty chamber or bad ammo.  Nature of the beast.

OK- Read the link above and it made sense.  Good simple info.  Thanks a bunch.

BTW- I believe that I like the "take it to the range" method of cleaning.  I will go after the burr first though.

I used the brush and some powder blast solvent...it helped a lot.

The problem may not be in the chamber (but often is). The locking lugs/channels  in the forward receiver are notorious for collecting cosmoline which, in turn, gives the bolt head a tough time in turning through it. I usually use Q-tips and Hoppe's to remove this, but it's a hard area to reach. Also, be sure the bolt is disassembled and thoroughly cleaned, inside and out.

This would be the first thing I would look at. Using a 12 gauge bore brush on a cleaning rod attached to a drill. Clean out the lugs as best as possible and then go to the range again to see if the problem happens.

I had the same problem once. If I put my finger in the chamber I could feel the burr. A long scratch was on the cases. I used some emery paper wraped around a cleaning rod in a drill. Only took a minute and the burr was gone. You must be careful not to polish to much or change headspace. If your not exactly sure of what you are polishing a gunsmith would be the best bet. Should only take him a few minutes.

I could not feel a burr.  I did use a worn out 12 guage brush and gave the chamber a scrubing.  The patch came out with some fouling but nothing major.  I am waiting to take her out and see if there is any difference.  I will carry my rod and brush and solvent with me just in case.  Thanks for everyones advice.  (Looking at getting some of the Romainian Silver Tip from Aim next week.)  

Your problem is simple. It is comsmoline that has "cured" so to speak from not being cleaned properly and then shot. The heat/time has made it rock hard and will take a few to remove. As mentioned before,take a drill and a 12/20 gauge brass brush and some solvent and work it out. It may take a few times but will work. Also try some Kerosene,this is what I always use to initially clean cosmo off my SKS's and 91/30's. It simply melts and rinses away. Dont do it on the stock like that though,use heat for the stock,oven,heat gun,hair dryer,etc.



You could take it apart and get a 4" PVC tube that is the length or just longer than the barrel and 2 end caps(some sealer too,to prevent leaking),cut it in half long ways,leave the ends intact so you can put the caps on the ends and fill partially with Kerosene and let the reciever end soak in the Kerosene then try to take the brass brush to it with the drill. You should be ready to shoot within an hour and a half after letting it soak.

http://www.youtube.com/watch?v=yXC_PQkLkNA



A lot of other good stuff from him.