Why does my brass look like this?

Discussion in 'Long Range Hunting & Shooting' started by Pbailey, Oct 28, 2011.

  1. Pbailey

    Pbailey Well-Known Member

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    Ever since I have started loading for my M700 ADL in 270, my brass has been developing a ring around the bottom of the casing. It happens whether the brass is brand new or been loaded 5 times. Ive made sure that I am well under max pressure and all of that, but still, it is leaving a ring around the bottom of my brass, and if you feel really closely, you can actually feel a slight bulge. I am not experiencing any signs of pressure, and I think that the small bulges could have an adverse affect on the accuracy with this rifle. I uploaded a photo of the groups that I will commonly get. Any idea why? the first shot down and to the left is the fouling shot. Both groups are totally different loads. Different primers, different powder, different brass, different bullets, and so its either my gun or me...But my biggest worry is the brass. Any help is greatly appreciated! Thank you!

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  2. IdahoCTD

    IdahoCTD Well-Known Member

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    It looks like that is where the die sizes the cases to. I'm not sure why you are getting scratches that go around the case instead of down the length though unless it's a lack of lube or the cases have expanded too much from over pressure and it's the die chattering trying to size the case. From the top picture it looks like your primers are pretty flat. I would try backing down the powder charge and see if it shrinks the groups. R-22, H4350, and IMR 4350 has worked well for me with 130's in the .270 before. It looks like your shooting 140's so R-22 might be a bit better then the 4350's. If a lower powder charge doesn't work I would try a different powder and if your getting the same group separation then I'd look at the bedding or lack thereof. In my experience erratic grouping is either powder or bedding related.
     

  3. panama

    panama Active Member

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    pbailey, those rings are from your chamber not the die, and that slight bulge you can feel is the case expanding to meet the chamber. you might try backing your die out so as to size the case just short of bumping the shoulder,so you get a slight resistance as you close the bolt. if you keep sizing your cases full length, that ring is the beginning of case failure. take a fine wire 3.5 " long put a small 90 Degree bend in it slide it into the case down to the base ,now drag it up against the side and if you feel it hang up at that ring, insipiant case seperation is going to take place shortly in as few as 3 more firings of that case,or less.and be sure and check case length after sizeing,i'm willing to submit that your case has grown .015 to .020 . you didn't say whether that first shot in both groups was out of a clean bbl? it seems consistant low left 1st. shot. and as for the rest of the groups the holes are touching!! you need to work this load up, jack o'conner'(mister"270") standerd load was 60 gr. of Imr- 4831 which is faster burning than H-4831, also check your O.A.L. just looking at your primers they don't seem to show any high pressure signs, you might try federal 210's or 215's. or cci 200-250 idahoCTD has a point but he's shooting 130's, do you have any idea how long your throat is in your chamber?? some times a flattend primer is not from hi pressure but from to much sizeing of the case for that particuler chamber,at firing the stricker shoves the case into the chamber at which time the pressure expands the case against the chamber walls radially, the back end of the case stretchs until it meets the boltface,some times the primer backs out just enough to get slammed back against the primer pocket,thus the result is what appears to be a flat primer. to check this when deprimeing look at the primer it will appear to look like a top hat. when i said work the load up thats just what it means .5 to1.0 gr. at a time. i"ve found REM. FED, are as much as 15 to16 gr. heavier than WIN.brass. so watch out and don't mix. i shoot fed,rem and LC-67 with the same load. win. are a harder but thinner brass. hope this has shed some light, and helps you. good shooting and GOD bless. ​
     
  4. Greyfox

    Greyfox Well-Known Member

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    The key input is that the effects you are seeing are with two completely different loads. It is quite possible the grouping and the brass effect is unrelated. It looks like the imprinting of the brass with the fine lines running the circumference of the case is the chamber tooling marks imprinting the case. I have had rifles that do this. This won't show at the base because the brass is thicker and doesn't expand to the same degree. the more pronounced ring at the base could be a headspace issue, caused by either pushing the shoulder too far back during sizing or excessive haedspace in the chamber of the rifle. Easy to check with a gauge.
    If that grouping is consistent with completely different load recipes, it could be a few things causing this:

    Vertical tracking issue in the scope, or a parallax issue that causes shift in impact with a change in head or eye alignment. If suspected try a different scope.

    A stock bedding problem. if so, rebed and make sure barrel is free floated.

    An inconsistency with either your hold, rest, or shooting position.

    Hope this helps.
     
  5. Buffalobob

    Buffalobob Writers Guild

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    Take the fired cases before resizing and roll a few across the table and see is the neck wobbles or the body is bent like a banana. If so, your chamber is not cut in line with the barrel.
     
  6. Rocky Mountain

    Rocky Mountain Well-Known Member

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    Looks like you have an over size chamber with bad rings in your chamber, who ever smithed this rifle did a bit of a boch job my advise is to get a gunsmith to cut of the treads of and rechamber it again.
     
  7. Pbailey

    Pbailey Well-Known Member

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    This is a factory rifle...but its been an absolute bear to try and get it to shoot well. I imagine that this would probably be why?
     
  8. WildRose

    WildRose Well-Known Member

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    Could well be Paul.

    Also it's hard to tell from the angle but it looks to me like your primers are showing some pressure signs. They seem to be almost flat with the base of the shell instead of just recessed a tiny bit. It also appears the firing pin holes are a little exaggerated which would also indicate high chamber pressure.

    If your chamber is a little loose that would account for the ring and apparent swelling and that would be exaggerated a bit by excessive pressure.

    Might try backing off a half grain or even full grain and use some new brass and see what it looks like.
     
  9. Loner

    Loner Well-Known Member

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    They look perfectly normal to me. Your chamber is a hair larger than some and the
    area below the webbing doesn't expand. Primers look good. I can't see the actual pin hit
    well from the angle the photos are taken at though.
     
  10. Sully2

    Sully2 Well-Known Member

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    I agree with what was said about possible flattened primers. They sure look like it.

    My question is this. What does FACTORY AMMO look like when fired?? If it has that ringed area around the base then the chamber is screwy. If the casing of a factory round looks A-OK...then there is a screw loose in your reloading procedure.
     
  11. royinidaho

    royinidaho Writers Guild

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    I'll add my two bits worth ok?

    Thoughts:

    1. Chamber cut with new or incorrect sized reamer. Reamer looks to have been rough. Either that or the chamber was polished with 80 grit.:rolleyes: Maybe the chamber suffered an attempt to polish out a defect. For whatever reason the chamber is quite large.
    2. The large chamber, in and of itself, makes little difference to much of anything except that volume is increased after the shot.
    3. If the chamber is out of round, as indicated by the ring you are developing is not uniform then you have problems. I had a Ruger 77 from a friend that shot like yours. The chamber was out of round. I marked each case with a file mark on the head. Loaded each round single shot with the file mark at the top. The next time I met him at the range the rifle shot lights out. He bought it back. Paid a little for the knowledge, though...:)
    4. If the ring is uniform i.e., the chamber is not out of round, then seeing as you are conservative with your loads only partial resize. By partial resize I mean size only until the die touches the case body. But size the neck at least one caliber down to insure sufficient neck tension to avoid problems.
    5. With the chamber being that rough the chamber is most probably grabbing the case body quite hard. This condition has been reported to be not good.
    Just some things to think about.

    Hope it helps
     
  12. dkhunt14

    dkhunt14 Well-Known Member

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    I think the primers look like they still have rounded edges so the load should be ok. You should get a headspace guage to put on your calipers so you can measure after firing and again after sizing to see how much you push the shoulder back. I don't like to bump more than 2 thous. I would cut a case in half and see if that is where the web ends and to make sure the cases aren't separating. It looks like where the die stops sizing the case. Matt
     
  13. J E Custom

    J E Custom Well-Known Member

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    Its just like Roy said;
    The chamber is large and rough. Typical of the factory chambers.

    The only way to realy fix it is to Set the shoulder back at least 1 full thread (Turn) and using a
    good reamer re cut the chamber and head space at the same time.

    This is normally caused by The reamer and /or the tail stock being misaligned durring chambering
    causing the reamer to run/cut on one side and allowing shavings to get under the cutting edge of
    the reamer on the opposite side scratching the chamber.

    If this is done it should cure most if not all of your problems.

    NOTE: Do not polish this chamber because it will only make it worse (Larger)

    J E CUSTOM
     
  14. WST416

    WST416 Well-Known Member

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    I'm going to leave the brass thing alone right now as I'm not sure that its a problem. I would like to know the order of your shots in the group. I'm not sure if both groups have a fouling shot or not but I'm going to guess first shot lower left fouler, next shot upper, third shot low and away from foul shot, fourth shot upper touching second shot, fifth shot lower touching third shot??? If this is the case the first thing I would do is try a different scope of any make just to see if the results are different. If the problem is still the same I would look at the barrel to make sure its fully floated and not touching anywhere. I would also check my screws on the stock to the action and make sure everything is ok there. I think this is way more likely your problems for your groups then the brass. Hope this helps.