New Reloader Questions Regarding Headspace and Pressure

Discussion in 'Reloading' started by Rymart, Jan 16, 2006.

  1. Rymart

    Rymart Well-Known Member

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    The following pictures are of once fired brass from factory Black Hills 165 gr BTSP Match ammo, fired in a Tikka M595 Master Sporter in 308.

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    If you look closely at the pictures you can see a slight bulge or ring just above the case head (I think). Also, I am new to reloading but, the primer looks flat to me. These are factory loads out of a factory match chamber. I have shot 240 rounds of this ammo and every piece of brass looks the same. The 'ring' marks were definately not there before the brass was fired. They were also not visible on the once fired Federal GMM brass. There were no problems with a sticky bolt handle. No apparent accuracy issues (printed between 0.25 and 1.0 inches at 100 yards with about 0.60 as the average). No problems chambering the fired brass in my rifle at all. I took a metal clothes hanger wire and sharpened it with a dremmel tool and bent the last 1/8 inch of the hanger 90 degrees and ran it down the inside wall of the case and didn't feel any obvious hang-ups. Before I thought much about this I had already case prepped 200 rounds of the ammo (flash hole deburred, cleaned,neck sized, trimmed, weighed and sorted, primer pockets cleaned) so unless it is necessary, I don't want to just throw the brass out, but will do so if necessary for safety.

    Additionally, when I started to prime the brass with Fed 210M primers it seemed like I had to exert more pressure than usual to seat the primers (remember though that I am new to this). When the primers felt like they had bottomed out they appeared to be (felt) slightly high in the pocket. When I applied substantially more pressure, I was able to get them to fit flush.

    If anyone feels like pitching in and helping me out, here are some of my many questions:

    1) Could this indicate a potential headspace problem with my rifle? Brass stretching and thinning above the matrix?

    2) Could these BHA factory loads be 'hot' in my rifle for some reason?

    3) Do I need to chuck this brass and start over with something else?

    4) Does the primer look flat to anyone else, or am I just looking at it all wrong?

    5) Will applying enough force with the priming tool to seat the primers flush (beyond where they seemed to bottom out) cause accuracy/reliability/safety issues?

    6) What else can I do about the primers? Leave them slightly high where they bottom out in the pocket? try different primers? Use a primer pocket uniforming tool (already ordered the Sinclair tool)?

    7) Am I worrying about nothing?

    8) Anything else I should be aware of?

    I appreciate the help in answering some or all of these questions.
     
  2. milanuk

    milanuk Well-Known Member

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    IIRC, BH uses Winchester at least for their .308. Winchester .308 brass tends to be kind of thin and undersized.... if you measure the web area on an unfired case I'm guessing it probably measures somewhere around .463-.465"... unfired Lapua brass measures more in the .468-.469 region. I think the SAAMI spec measurement for your chamber is somewhere around .470", though it could be slightly bigger (measure your fired cases to get an idea). So in closing, no, I don't think there's anything wrong w/ your brass just because it has a little bulge there... it's just an artifact of the kind of brass being used and the plus/minus tolerances involved. FWIW, Winchester brass shoots just fine even w/ the bulge, and lasts a good while... maybe not as long as Lapua, but it costs about 1/2 as much or less.

    HTH,

    Monte
     

  3. gonehuntingagain

    gonehuntingagain Well-Known Member

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    The same thing happens in my factory Rem 700 308, as well as 4ked Horn's factory Rem 700 308. 4ked asked about this a while ago and the consensus was that the factory rams the reamer into the barrel at Mach 3 and it is just the sloppy factory chambering that is causes this. Who knows how many barrels were reamed before your barrel.

    The primers look like they just conformed to the bolt face, but in my rifles, all primers look like that. I figure as long as there is no primer flow or piercings then all is well.
     
  4. royinidaho

    royinidaho Writers Guild

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    I'd pick your #7 and give you very high marks for your concern. You're asking all of the right questions and getting some good answers.

    Flat looking primers are difficult to judge as some manufacturer's primers are softer than others. You mentioned that you had no extraction problems which is a better indication of pressures.

    Createring on the primer around the firing pin indent, of which you have none, is another indication of pressure but is dependent on fit of firing pin to firing pin hole in the bolt.

    Not exactly sure of what you mean by the first part of #6? However, the primer should never (as in Never) protrude above the case head. The bolt will press it in. If the bolt 'slams' as in a semi-auto you may have a whole nother problem. Not good. Think about it.

    It may be that your chamber is a bit on the large size at the back end. If you full length resize with dies that are smaller than the chamber diameter you'll work the cases a bit excessively. Just another interesting thing to learn.

    You're headed in the right direction, keep on truckin'
     
  5. 308sako

    308sako Well-Known Member

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    The look of your brass is but one indicator of what happens upon firing. The look which you are agonizing over is important, as others have pointed out... you are doing well. Could be your headspace is just a slight bit large for that particular lot of brass, NOT A PROBLEM though. As to the primer pockets being tight and sort of shallow, that's good news as to pressure signs. I use and love the sinclair tool you ordered, because I believe that accurate reloads start with evenly seated primers. never use extra force to seat primers (from an accuracy standpoint.) Saftey is of course a different issue. From the size of your groups, and your attention to detail I believe you will do very very well at shooting/reloading. Enjoy the sport.
    Dave
     
  6. goodgrouper

    goodgrouper Well-Known Member

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    Hello Fishry.
    Great pics and your explanation of your questions helps tremendously to diagnose the problem.

    I hate to tell you, but you have a grossly oversized chamber and undersized case heads (normal in every way for Winchester brass) and that is what is making that big bulge ahead of the web. It is not a big deal for the most part, just unsightly. The only areas where it might be detrimental to your enjoyment are these:

    A badly oversized chamber will allow the thick side of your brass (which is found in every brand from Lapua down to Lake city) to grow in it's direction every time it is fireformed and can stretch the brass to the point where it can "pull" the bullet release to one side. Then the next time you fire it, the fat side might not be in the same position in relation to your chamber and it will fireform to that side and pull the bullet in another direction. The only way to get around this is to "index" the cases. I found the best way to do this is to file a small notch in the case head on the thick side of the case and make sure to put it in the chamber with that mark up or out. It doesn't really matter where the mark is just as long as it is in the same place every time you chamber the round.

    I had to do this on one of my own guns and it shot fine as long as I paid attention to the mark. But after awhile, I decided to just have a reamer made to my specs for a specific kind of brass in which there would be no "bulge" or "belly out". This solved the problem entirely and was less hassle. Or, you could measure several different brands of brass and pick the one with the largest case head dimension. Each brand has a different dimension despite SAAMI specs that say they should be .473" or whatever.

    Doing this will help make up the slack if you don't want to spend $200 having a reamer made and then having a good smith rechamber.


    One other problem that might arise from a "bulge out" is when you go to resize. If your particular dies are on the small side in the web area and your gun is in the big side in the web, then you might have Full length resizing problems down the road. This can be remedied by having a machinist "open up" the arse end of your die to a bigger diameter. THis can usually be done for $20.



    As for your q's, here we go:

    Q1 answer: Doubtful. Headspace is probably ok, just the diameter of the back end of the chamber is big. Headspace mainly deals with the length of the chamber from the bolt face to the datum line. And thinning will be minimal.

    Q2: answer: They are definetly not mild but appear to be ok given the details you mentioned. One thing to remember is that BH uses ball powder which is sensitive to ambient air temperature and thus must be closely watched for pressure in changing environments. If those pics are of ammo shot in January, it may be too hot for your gun in July. Watch it closely from month to month.

    Q3: answer: It is up to you. It can be made to work doing what I have detailed, but you might just choose to rechamber or use bigger brass.


    Q4: answer: It's flattening but not terrible.


    Q5: answer: I wouldn't recommend forcing the primer in. Use a good pocket uniforming tool and everything will be perfect.


    Q6: answer: If you leave the primer above flush, it will slam back against the bolt face, and if there is enough pressure present, it will open up the pocket by force. All primers actually "pop" out of the pocket under firing and are in effect re-seated into the pocket but the ammo shouldn't be overloaded too bad or pocket enlarging will result. Leaving the primer above flush is to some degree is technically safe, but has terrible effects on accuracy. I would strongly recommend seating them flush or just below flush. Make room with the uniformer.


    Q7: answer: Yes and no. Just be aware of what is going on. Everything is notable even if it may appear insignificant.

    Q8: answer: none that I can think of at this time. You are doing good! /ubbthreads/images/graemlins/wink.gif
     
  7. wapiti13

    wapiti13 Well-Known Member

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    fishry, In your third & fourth photo, I can see the radius on the edge of your primers. "Flat" primers will not show this radius. Also, as stated above, no brass flow from the striker is shown. when you get a reverse crater from your striker dent, then begin to worry. Sorry for the factory oversize problems. /ubbthreads/images/graemlins/frown.gif
     
  8. LB

    LB Well-Known Member

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    I think you have good advice. Your primers look a little flat, but as others have said, not excessive, and there doews not appear to be any cratering around the primer detent.

    Yes, your chamber does appear to be oversize, but that's not exactly rare, and not particularly harmful, if you necksize or full length. Depends on how you are satisfied with chambering?

    It definitely does not look like case head separation, uncommon in a factory unaltered rifle. Case head separation is what we see in bad rebarrel jobs, for the most part.

    I also pick #7, I don't really see much to worry about? I have a rifle that shows about like your photos. I think it's over thirty years old and I have been using it for twenty....I full length resize it, accuracy is adequate, but I don't use a hot load, which I judge by the primer.

    Good hunting. LB
     
  9. Rymart

    Rymart Well-Known Member

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    Thank you everyone for your advice, and kind and encouraging words. Sorry it took me so long to reply. I've been out of the country on business for a few days.

    The rifle was purchased from a reputable gun smith as new and unfired. It had the factory barrel removed by the smith, who had planned to rebarrel it and turn it into a Palma Match Rifle. I requested that he re-install the factory barrel (since they are usually fairly accurate, plus I saved some much needed $$$'s by doing this). Tikka/Beretta claims that the chamber is a match chamber with tighter tolerences than a typical factory rifle (on a phone call with Beretta). Apparently the chamber is not really all that tight. Oh well. I plan to practice a lot and learn as much as possible about reloading and LR shooting on this barrel, then rebarrel to something like a 260AI.

    I got the itch to reload the other day, so to prove to myself that I could trust the brass, I 'opened' a piece up. Here is what it looked like:

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    From there I used some of my unsorted BHA brass (until the Sinclair primer pocket uniformer arrives). I applied a good amount of force with the press to prime the brass with the primers flush to the case head. I used IMR4064 powder. The Sierra reloading manual showed 43.4 grains to be the 'max' load for the 168 gr. BTHP, while the IMR reloading book showed 45.9 grains to be the 'max' load for the same bullet, HMMMM??? (any advise on what to do with this?) I started low and worked up to as high as 44.0 grains of powder, so far, with no apparent signs of excessive pressure. The weather was windy, cold, and gusty with winds around 15 to 25 mph and shifting between 7:00 and 10:00. I tried to pull the trigger when the wind felt similar to the previous shots. All recorded shots were at 100 yards. Here are some of the results:

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    Here are some 'baseline' groups that I shot with factory ammo on the same day:

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    It seems to me like 42.7 grains shoots well, as does 43.2 grains.
     
  10. LB

    LB Well-Known Member

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    First, you don't have any signs of case head separation. You have a slightly oversize chamber. Unless you plan on entering tournaments, you can use that rifle and that brass without concern. And, (just a guess) your gunsmith probably knew what he was doing, intending to discard the original, and wasn't completely honest with you, although you asked him to swap barrels.

    It's apparent that your handloads are considerably better than the factory ammunition you selected.

    I don't know what to tell you, as far as resizing versus neck sizing. There may be an advantage one way, and a different advantage the other way; hard to say?

    Good hunting. LB
     
  11. Rymart

    Rymart Well-Known Member

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    Thank's again for your help and advice.

    Yeah, so far I'm pretty happy with the hand loads. In case I did not mention it, I am neck sizing with the Redding Competition Neck Sizer die set. If I run into any problems chambering the rounds, I will 'bump' the shoulder back a minimum amount with the body die.

    Even with the oversized chamber, for now, the rifle seems to shoot at least as well as I do, if not a little better.

    My OAL gauge has not shown up yet, so I reloaded the OAL to match the factory ammo at 2.800". For when the OAL gauge does show up, can someone suggest some seating depths that I should try? For 168 gr SMK's, 165 gr SST's, 165 gr SGK's, and 180 gr SGK's? My magazine will allow an OAL of 3.000".

    Also, the Base-to-tip length of my loaded rounds varied from 2.997" to 2.805". Is this variation normal? I think the Redding Competition seating die seats the bullets from the ogive (am I right on this?) If that is the case, then am I just seeing the difference from ogive to tip on the SMK's or do I have other problems?