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  • 1 Post By veitnamcam
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Thread: Question about chambering

  1. #1
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    Question about chambering

    Hey guys, I have a question for all the gunsmith types,
    I have a ruger m77 hawkeye, I was having a play around with some neck sized once fired brass today and I noticed a pronounced ridge running around the brass about 7mm up from the bottom, I dropped one into the chamber of the barrel and it protrudes quite alot back into the action. After a whole lot of looking and measuring I have come up with the face of the bolt is 6.8mm from the rear of the barrel and the front of the bolt locking lugs are 4.2mm from the rear of the barrel. Does this sound normal I always assumed the barrel would be set back almost touching the front of the bolt locking lugs maybe .5-1mm clearance and the whole piece of brass that contained the powder was inside the barrel. I'm wondering if they didn't thread the barrel enough and this has left some unsupported brass. This may explain some of the issues I have been having with my brass life. Of course this may be normal as well? Any ideas? Cheers.

  2. #2
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    Photos?

  3. #3
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    Sorry guys I've got something wrong here, it was keeping me awake so I have had another measure and I was wrong. The case only protrudes 4mm behind the barrel and that would give the locking lugs and extractor less than 1mm clearance, so right where I thought it should be.
    But I still have this odd lump around the case it is about .15mm larger at 7.4mm up from the bottom, they are all the same. Could this be a fault in the chamber, this would explain my sticky case removal at low charge rates.

  4. #4
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    Name:  20180118_234750.jpg
Views: 161
Size:  1.27 MBName:  20180118_235549.jpg
Views: 161
Size:  1.34 MB

  5. #5
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    Is that once or twice fired brass? I had a similar issue with my 6.5x55 swede many years ago and the result was on extraction the line was where the case separated. It stayed complete for the shot but when you pulled the bolt back there was a neat "cut" and the bit behind the line was in the extractor and the rest stayed in the chamber. It fell out when I tapped the butt on the ground so was not very stuck at all. Not sure if your issue is the same but my cases looked exactly like your pictures.

  6. #6
    Almost literate. veitnamcam's Avatar
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    Just looks like a large chamber to me?
    What rifle?

    Sent from my SM-G390Y using Tapatalk
    Kiwi Greg likes this.
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

  7. #7
    Member Marty Henry's Avatar
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    Its not unusual to see a discoloration at the point where the case is not supported by the chamber and the web is exposed. Measure the depth of the case and compare that to the case length overall, if the internal measure matches the ridge that would be informative.

  8. #8
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    That is once fired hornady superformance.
    Ruger m77 hawkeye stainless 6.5x55
    That mark is up inside the barrel (inside the chamber) by about 3mm.

  9. #9
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    The first picture looks pretty normal, well at least if you were FL resizing. The virgin bit of brass at the base is where the die doesn't touch.

    The second pic is definitely not normal looking and suggest imminent case failure from separation at the web. This is generally from repeated firings in a chamber with excessive headspace and being FL sized each time, thereby really working the brass.

    The way to check for problems is with a probe- straighten out a paper clip then bend the last 3-4mm at a right angle. When you slide this back and forth along the case sides near the bottom of the case, you will feel a depression if there is imminent case separation. Good cases will not have this shallow "trench" down near the base (web). Discard any that have that trench.

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    Member Ryan_Songhurst's Avatar
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    Does it still shoot stuff?

  11. #11
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    What does the brass look like when you've fire factory ammo in the rifle? This might tell you whether it's the rifle or a reloading issue.

    I thought that the problems could have come from excessive headspace from FL sizing but you say you've only neck sized the brass.

    Can you see or feel (with cleaning rod etc) any irregularities in the chamber where that line forms?

  12. #12
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    The case expansion is perfectly normal, and below that band the case is solid. The chamber will be within spec, although closer to the upper limit. It is quite safe.
    veitnamcam and madjon_ like this.

  13. #13
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    Ok, thanks for the input every one, I have measured the brass and looked up the chamber dimensions, (https://en.m.wikipedia.org/wiki/6.555mm) and even the blown out ridge is within spec, I'm guessing as mentioned above below that is solid brass which would not allow it to blow out to match, what might be making it more apparent is the hornady brass at the very base is ever so slightly undersized according to the chamber spec.

    I will continue loading up rounds and work up a load.

    Thanks

 

 

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