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Thread: Chambering problems

  1. #1
    Member AKdutch's Avatar
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    Default Chambering problems

    I have been reloading for my Remington MDL 7 in .300 SAUM. I have reloaded thousands of handgun bullets, but rifle loading in pretty new to me.

    The problem I'm having is that about half of the cases I have loaded do not chamber in my rifle well. The case will chamber easily until the bolt almost closes. Then approximately half the cases make the bolt very difficult to close. I'm having a difficult time trying to explain this, so bear with me. I was able to close the bolt on all 20 rounds except one. About half chambered easily. The other 10 rounds chambered easy until I was locking the bolt handle in the down position. None of the fired cases showed any signs of high pressure or looked any different than the others. My groups were all between 1.62" for three shots at 100 yards, down to .455" for three shots. My last five shots grouped in x ring in .859".

    When I got home I measured the cases that were hard to chamber and they all measured exactly the same. I then checked the 20 cases that I had prepped already except for powder and seating the bullet. I chambered all 20 cases and 8 out of the 20 were hard to close the bolt on. All the cases were reloads from being fired in my rifle and I could see no difference in them at all, even after measuring them each with my digital calipers. The only thing I can think of is that the shoulder is not the same on all the cases. I full length resized the cases and trimmed all to within .003". I am stumped. Any suggestions or possible reasons? BTW, I am pretty proud of that 5 shot group. Its the best I've ever shot by far. John
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    Member .338-06's Avatar
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    Default

    Off the top of my head; are you loading the rounds to the correct overall length? Try chambering your resized shells before you seat the bullet (and powder, of course!). If your empty shells chamber fine you'll know it's something to do with bullet seating.

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    Member AKdutch's Avatar
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    Default

    Yea, I tried that. Last night I prepped 50 cases (polished, resized, deprimed, trimmed to length, deburred, cleaned primer pocket, and primed the cases). I loaded 20 of them to shoot today and left the rest on the bench. Those were the ones I checked when I got home. But thanks, John

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    Default neck thickness?

    Next time you have a tight chambering round, remove the round and look at the bullet for rifling marks.

    If none are present, fire the rounds and mark them, take the cases and a ball mic and compare the neck thickness of those that chamber easy vs. those with problems.

    Take at least 4 measurements per neck. 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock.

    Take these measurements at mid neck and compare.

    If this dosen't solve the mystery then section a case lengthwise.

    You will probably see a ring forming at the neck shoulder junction.

    This is from loading long heavy bullets in short necks.(the bullet bases drop below the neck/shoulder junction and into the case)

    The pressure delay-dwell time from the bullet being below the neck is like a thumb over a gardenhose.

    Lots of gas trying to go around the edge of the neck base causing brass to heat above normal and flow into the neck/shoulder junction. (I got several posts on this phenom)

    I don't know of a way to correct this once it happens.

    Just trash the brass as scrap metal and get more.

    jedi

  5. #5
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    Default compression?

    Also, if this is virgin brass giving you problems maybe the load is being compressed.

    This will swell some cases more than others while seating the bullet.

    I assume you are loading 200 grainers from the pic.

    These will intrude into the body and powder space of the stubby rounds when loaded to an OAL to function in the small magazines.

    jedi

  6. #6
    Member AKdutch's Avatar
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    Default

    Quote Originally Posted by jedi rifleman View Post
    Next time you have a tight chambering round, remove the round and look at the bullet for rifling marks.

    If none are present, fire the rounds and mark them, take the cases and a ball mic and compare the neck thickness of those that chamber easy vs. those with problems.

    Take at least 4 measurements per neck. 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock.

    Take these measurements at mid neck and compare.

    If this dosen't solve the mystery then section a case lengthwise.

    You will probably see a ring forming at the neck shoulder junction.

    This is from loading long heavy bullets in short necks.(the bullet bases drop below the neck/shoulder junction and into the case)

    The pressure delay-dwell time from the bullet being below the neck is like a thumb over a gardenhose.

    Lots of gas trying to go around the edge of the neck base causing brass to heat above normal and flow into the neck/shoulder junction. (I got several posts on this phenom)

    I don't know of a way to correct this once it happens.

    Just trash the brass as scrap metal and get more.

    jedi
    ++++

    Thanks for the advice. I kind of tried what you stated. I took one of the cases that was hard to chamber and colored the case from the top of the neck down past the shoulder with a sharpie and rechambered the round. The case did not have any rub marks on it. I had spent quite abit of time trying to figure out the right seating depth of the bullet and discovered that the magazine length was the limit on seating the bullet and had quite abit of space left before the lands. So that wasn't the problem.

    On the second option, sounds like a possibility, but all my brass was originally factory Remington 180gr partitions I saved from shooting at the range and was the first time being reloaded. Could loading a longer bullet than the original be a problem? Could there be something wrong with my dies? The are Hornady and haven't been used much. I've only loaded about 100 rounds and this is the first time I've had this problem. Thanks for the info, let me know if I've misunderstood some info you gave. John

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    Default another SWAG

    OK. I will give it another SWAG. (scientific wild ***** guess).

    Try measuring the rim diameter and compare.

    Maybe some oversize rims are sneaking in.

    That round is based on the .404 jeffrey with the rim turned smaller I believe if my memory serves me right. (I never loaded any short fatties yet)

    Maybe some have larger than spec rims.

    Also, and I hope this ain't it....check primers for being below flush.

    You never wanna be seating high primers via the bolt face while chambering.

    jedi

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    Member Float Pilot's Avatar
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    Default

    It sure will be intersting to see how this works out.

    For chuckles and grins you might want to weigh your brass. See if the trouble makers are heavier or lighter for some reason. I weigh mine anyway just to keep my loads uniform. I have had some interesting variations in Remington Brass. Some of them were super hard and held less powder than Winchester (olin) brass.

    I did have some winchester brass that slipped by my trimming process. Every now and then one was hard to chamber and the recoil was a LOT more on that round. It turned out that a few were long enough to make rifling marks on the case mouth from my super tight competition chambered 7x57mm. It must have been an all night reloading party or something.

    Have you tried rotating the cartridge by 90 degrees at a time to see if it suddenly becomes easier to chamber. I have never seen an out of round chamber or loading die, but I have heard that it has occured.

    I had one rifle with a chamber that was so oversized that the case head would swell up pretty bad. They did not resize very well and you could see a big step down just above the rim. So that gun was rebarreled in a big hury.
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  9. #9

    Default

    Have you reamed the inside and outside of the case necks? They should be reamed inside and outside lightly.

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    Default Chambering Trouble

    Sounds like headspace to me. You are not pushing the shoulder back far enough. Take one of your prepped cases that is not chambering or chambering stiff and run it through the sizing die again, BUT this time screw your die in further (like another 1/8 turn). Try chambering the round again, if it wont chamber go another 1/8 turn. I wouldnt go too much further than 1/4 turn past the shell holder touching the die when the press is at its top of stroke, or you could end up with excessive headspace.

    If you want to get your headspace dialed in real well, than get a stoney point headspace adapter thingy. It will attach to a dial caliper to measure headspce from the base of the case to the shoulder. Then measure some once-twice fired brass. That is then your reference, so re-size all you cases to .001-.002 below that number so they will chamber easily.

    ie. Cartridge X once fired brass measures 3.045
    Re-size to 3.043-3.044

    This will also increase case life and possibly accuracy.

  11. #11
    Member AKdutch's Avatar
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    Default OK

    I'm going to go try the headspace thing now, but wanted to throw something else out. I measured all the cases, good and bad in as many ways that I could. I found out one thing, but it seems backwards to me. I measured the outside neck diameter of the cases that chambered easy and they were all .333 or .334. I measured the outside neck diameter of the cases that chambered hard and they were all smaller, as in .327 or .328. What the heck.

    This morning I remembered that some of the cases were hard to get out of the die after sizing them and thought maybe the deprimer pin (the teardrop shaped part) was making the shoulder too long or something. I removed the pin and tryed resizing the bad ones, but that didn't change anything.
    I try to change my die seat depth and get back to ya. BTW thanks. John

  12. #12
    Member AKdutch's Avatar
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    Default TomM you win the prize

    Your a genius, Took about 3/16 of a turn and they chamber easier than the others now. Thank you very much for all of the input. I knew you guys would figure it out. John

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    Default gremlins

    Hmmmm.....sometimes those gremlins hide in plain sight.....right under your nose.

    jedi

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