Bolt won't close

  • I headed out to try and shoot this afternoon before this winter storm hits me here. I wasn't able to chamber the first round I tried to load.

    This is a lone peak fuzion action. I'm shooting factory American Gunner 140 gr ammo. I've put 250 rounds of a different lot of the same ammo with no issue and 45 rounds from this lot a couple weeks ago with no issues.

    When closing the bolt it feels like it hits a hard spot right before it is able to close far enough to rotate. The bolt is definitely not closing far enough for it to begin rotating.

    I grabbed 10 rounds and numbered them. I tried running them all through a number of times. There appears to be no pattern to which rounds will chamber and which will not. It seems about 2-4 of the 10 rounds will not chamber as described above. If I grab those same rounds and run them through again the rounds that previously did not chamber may chamber, and rounds that chambered the previous time may not chamber. I did this several times with different results each time. I tried with a 10 round mag, 5 round mag and hand feeding with similar results.

    I've got about 300 rounds through since the last cleaning.

  • it sounds like you either have some oversized brass or something is dirty or accumulating a build up or film on it. I would check your lugs to see if they are starting to Gaul at all then clean them and the bolt face along with the chamber. I have found that just the tiniest bit of dirt in the chamber can do some funny things. You could also check the neck diameter on your loaded rounds or if the necks are catching at all where the bullet neck junction is.

  • @bear9350 Do you use a suppressor and store your rifle vertically? If so it could be a carbon flake.

    A good inspection of the chamber would be recommended.

  • I looked at the chamber and bolt as best I could. I do not have a bore scope but it is on my list of things to aquire. I then cleaned the chamber area and the bolt head. This made no apparent change in the results.

    I took a bunch of measurements from the first and second lot of fired bullets and some unfired rounds from the second lot.

    I also cycled some more of the unfired rounds from both the first and second lot through. Some of the second rounds from the first lot would not close like the fired rounds I was seeing. In the pieces of the first lot I tested they all closed with no issue.

    It was at this point I realized that if the bolt would not close on the round it would also not extract it. I then ran a bunch of rounds through where I would set the round engaged in the extractor then load it. I had no issues like that. The rounds that the bolt is not closing on are not making it past the extractor and never making contact with the bolt face. If I really slam the bolt hard I can force it past the extractor and then all works normal. I'm talking hard. I would not be able to do this without completely disrupting the NPA of the rifle.

    Not really sure where to go next. Is there something wrong with my extractor or is it in the ammo?

    I can post up the measurements I took if anybody wants to see them but I thought they looked ok.

  • Did you measure the diameter of the case rim?

    Post a picture of your bolt face please.

  • Pictures of the bolt face.



    Travis requested these pics also. He is going to get me a new extractor with a bigger chamfer and said that was the issue.

    I did measure the rim diameter of 10 pieces of each lot of brass.

    The first lot that seemed to work good was slightly smaller at .4640-.4640".

    The second lot seemed to be running a bit larger at .4650-.4665".

    Edit: All my measurements were done with a cheap $30 caliper I generally just keep in the shop for dirty work. I left my food set at work.

  • Yup, you can see where the rim is hitting on the flat part of the extractor.