Model 700 chambering issues

Discussion in 'Gunsmithing' started by jmason, Aug 13, 2008.

  1. jmason

    jmason Well-Known Member

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    My 700 LA is having chambring issues (I think). I have to put excessive force on the bolt to close it on FL resized brass, and some new brass. I took some FL sized brass and measured Head space with a cartridge HS gauge. They vary aliitle 1/1000th give or take, but if I take two peices of brass both measuring the same(to the datum) one will chamber fine and not the other. So I thought I'll try some brand new Nosler custom brass. Most of it measures the same as my FL sized brass. I start chambering it and I still have some that chamber with more difficulty than others. So I colored the shoulder of some of the new brass and I get a ring on every one in the shoulder area but the mark is not exactly on the shoulder. the rings show just before the shoulder crease on the brass on 3 different brand new peices. This does not seem right, does anyone have any insight?
     
  2. NesikaChad

    NesikaChad Well-Known Member

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    Is this a brand new gun or one you just acquired? I have to assume it is.

    If this is redundant, I apologize, but lets cover the fundamentals a bit.

    Strip the bolt of anything that has or is driven by a spring and recheck your headspace with a SAAMI spec go gauge. The bolt should fall into battery with no effort on your part.

    If it does not do that, then you have a chamber that's tight.

    There are a couple options, the first is the "right" answer, but all will work.

    1. Either send the gun back or chase the existing chamber with a finishing chamber reamer of the same cartridge.

    2. Size all your brass so that they will chamber, which will require bumping the shoulder back a bit and maybe trimming the necks if its really out of whack.

    3. Taking a cut off the back of the bolt lugs or from the bolt face to loosen things up. Understand that doing this has an effect on the timing of the action and it will reduce the amount of firing pin travel (not protrusion, just travel) Unless we are talking HUGE amounts I wouldn't concern myself with that though.

    Now, if the gauge does indeed fall on the chamber and the rifle is in proper headspace, then I'd obtain a small quantity of brand new brass and go from there.

    Good luck.
     

  3. jmason

    jmason Well-Known Member

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    Is this the correct go-gauge? It's from Brownell's:

    319-306-049
    .30-06, GO

    I did try new Nosler brass and had some that chambered and some that fought back. I also had the same results with FL sized brass. All of with had the same length to the datum.
     
    Last edited: Aug 14, 2008
  4. NesikaChad

    NesikaChad Well-Known Member

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    Call David Kiff at Pacific Tool and Gauge in White City Oregon.

    All tooling is not created equal.

    Nough said.


    Dave will do you right.

    Good luck


    Chad

    Chad Dixon
    Gunmkaker
    LongRifles, Inc. (coming soon)
     
  5. NesikaChad

    NesikaChad Well-Known Member

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    If some are squeaking in then I'd guess you are close to the minimum side of the HS for the cartridge. Not a bad thing necessarily, but I think you'll want to hear this part.

    About four/five years ago I was building a 6mm-284 for a guy. I get the rifle done and it just will not shoot. Groups just absolutely sucked balls.

    So, naturally I'm pissed, I'm boring a hole through my skull with my finger with all the head scratching, and I'm spending long hours at the reloading bench/test tunnel trying to figure this thing out because I KNOW I built it right. It was a Nesika K action, Kreiger barrel, and a bad ass looking laminate heavy bench stock. No reason for this rifle to be acting stupid like this.

    Well, turns out the HS was tight on the gun. I switched to new brass and it had chambering issues, just like your gun does right now.

    I pulled it apart and squeaked in the last little bit and suddenly it was a whole new rifle. It hammered groups that'd scare you to death, just like it was supposed to.

    I couldn't tell you to this day why it made such a difference, nor do I care. It worked and I've not made the same mistake again since. Better to be lucky than good right?

    Good luck


    Chad Dixon
    Gunmaker
    LongRifles, Inc. (coming soon)
     
  6. jmason

    jmason Well-Known Member

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    You lost me on "squeaked in the last little bit". Did you ream the chamber to get a little more HS?
     
  7. NesikaChad

    NesikaChad Well-Known Member

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    Exactly.

    Just threw it back in the lathe and fed the tool in by hand to where it just shaved a "red one" off and then did the ol 320 fluff and buff at low rpm to get the surface finish I want.

    Half hour of work at the most.
     
  8. yorke-1

    yorke-1 Well-Known Member

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    This may not apply here, but I had a similar problem with my Father-in-Law's rifle. The gun was a Model 70 Stainless Classic in 300 WSM. It never really shot well. Groups averaged 1.5-2" on a good day. Sometimes much worse. He sent it home with me because I needed a project and this sounded like the perfect one.

    After shimming the action with washers to float the barrel, and adjusting the 4.5+ trigger the gun shot 1-1.5" groups pretty consitantly. From there I started working on handloads. After resizing 100 once fired cases from this gun and making up various loads to test I decided to run a few through the magazine just to make sure they'd function.

    The first round went just fine. The second round wouldn't chamber. The third round chambered but only with a fair amount of force. I checked my overall lenth to make sure I wasn't jamming the bullet into the rifling, but that wasn't the case. Then I tried a factory round and it chambered just fine. I scrubbed the chamber and that didn't help. Now I was confused.

    I took an empty full length sized case and tried that. I chambered fine. When I tried to chamber the same case again, it wouldn't go. I tried again and it wouldn't go. Tried a third time and it chambered, but it was pretty tight. Now I was really stumped. I took a marker and put a reference mark on the case. Then I tried to chamber it with the mark on top. The round didn't chamber. I then rotated the case .25 a turn and tried again. I continued this and after rotating the case 270 degrees, it chambered fine. I tried it again and again with the witness mark in the same spot and it worked every time. If I rotated the case though it wouldn't work.

    Now that I knew that there was a chamber problem I took a look at the once fired brass. When I rolled them on a flat surface, they had a noticeable bulge on one side. To fix this, I trimmed .005 off of the shell holder and resized the cases a little at a time until the die was adjusted to size the case down enough to chamber. Then I had to pull all of the rounds that I loaded, resize, and reload them.

    In the end it was worth it. The rifle ended up shooting groups in the .75-1" range with anything I tried. Especially the 168 TTSX which would occasinaly shoot slightly better than .75. I destroyed every case after it had been fired twice. I just wasn't comfortable loading the cases multiple times having bumped the shoulder back like I did. Unfortunately my Fater-in-law decided that the rifle was damaged goods and traded it off for a SRH 454.
     
  9. jmason

    jmason Well-Known Member

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    I'll bet my issue is very similar. I think I'll get .001" or .002" removed from my die or shell holder and see if that helps. I tried another die and it really didn't change anything. So I took some brass and put excessive force on it in the die to make sure the shoulders were getting pushed back as far as possible. That seems to help, but some of them still required extra pressure to close the bolt. If that little bit of trimming off the die or shell holder helps and I get it shooting well I'll be happy. I'm dredding the thought of sending it out to a smith because if they're going to pull the barrel I'll end up going further($$$) than correcting the chambering issue............:D

    Do you guys think that by trimming my die or shell hold by .001" or .002" (if that works) I'll end up with a safty isuue or just a shorter life cycle on my brass?
     
    Last edited: Aug 18, 2008
  10. AJ Peacock

    AJ Peacock Well-Known Member

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    Sometimes it's tough (impossible) to push the shoulders back and resize brass that has been shot several times. The brass gets hard and is very springy, causing tough chambering. Then it's either time for new brass or time to anneal the brass.

    Just another thought.


    AJ
     
  11. ackleyfan

    ackleyfan Well-Known Member

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    Take a set of automotive feeler guages and start out at .002 and slide it between the case and shell holder and size the case and this will take up the slack between the case and shelholder and give you a little more sizeing, just increase the size of feeler guage until a case chambers in your rifle this will tell you how much to take off the bottom of your die or the top of your shellholder! Good luck
     
  12. jmason

    jmason Well-Known Member

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    Thanks guys I appreciate the info. I did try indexing FL sized rounds in the chamber and found that indexing them does allow chambering without force. So somethings crooked.

    I've been shooting 135 smk's and got nothing w/ RL 22. I'm now in the process of IMR 4831. I still have 2 or 3 trips left to make to the range before I exaust this powder as well. If I come up empty handed here I'll probably be sending it off..
     
    Last edited: Aug 19, 2008
  13. summitsitter

    summitsitter Well-Known Member

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    I may have missed this somewhere but does factory ammo chamber easily.. Is new brass (unsized or loaded) hard to chamber or is it just resized fired brass?
     
  14. jmason

    jmason Well-Known Member

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    I have some new Nosler brass that doesn't chamber completly right but doesn't require anything near the amount of force that the resized brass does.