Accuracy leaving with worn brass?

larryh128

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I loaded and shot a very narrow ladder (8 rds) as I knew the approximate range I wanted to be in. This brass has been shot a lot during testing. I've re-used the sames cases instead of cracking into my cache of new brass. As I primed them, I discarded 2 cases and said this is the last loading on the other 6. Primer pockets weren't totally loose but not as snug as I like. I substituted 2 new cases and charges them with the 1st 2 increments. I'm only increasing charge weights by .1 as I'm pretty locking into a specific charge range. The 1st 2 rounds at 300 yds went into the same hole then when I hit the used brass they opened way up and moved up and left. I've shot enough ladders to have seen a lot of things happen with barrel harmonics but it really got me wondering if the last 6 were the cause of just flat out worn brass. I'm going to re shoot the 6 with new brass but has anyone seen something like this? Rifle is 6.5 SAUM/GAP and is a hammer.
 

larryh128

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These cases have at least 8 loads on them, possibly 10 to where the pockets aren't as tight as I like them. The loads are moving. Top loads were hitting over 3300 x 130 gr Berger Hybrid. No extraction issues or flattened primers. When I hit about 3350 the base started growing about .001 so that was definitely over pressure. Anything 3300 or under had 0 base growth. It could be nothing but hitting the ceiling for the barrel. The loaded that shot into the same hole were just below 3300. 3280 & 3290.
 

Supersubes

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    Maybe I missed it but what were the velocities for the two virgin cases? Tell us more about the entire load? Jamming bullets, neck sizing only, etc. Why running another ladder this late in the game? Measuring base growth is a one time deal for virgin cases. Its just not reliable after that.
     

    Steel head

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    larryh128

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    Maybe I missed it but what were the velocities for the two virgin cases? Tell us more about the entire load? Jamming bullets, neck sizing only, etc. Why running another ladder this late in the game? Measuring base growth is a one time deal for virgin cases. Its just not reliable after that.
    Bullets are not jammed , full length sized, didn't know anyone still neck sized. Velo was 3280 & 3290 on new cases. No base growth. RL-26. Why ladder? Trying to pinpoint the last tenth of a grain. I probably have it as 2nd bullet didn't open 1st hole more than .030.
     

    Supersubes

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    Some people do still neck size like my brother from another mother @Steel head. He got shorted a chromosome though I think. 👊🏻

    Gosh, it would take a lot of rounds to discern .1 gr in a case that big imo. And of course any change in temp with RL26 would blow you right out of any “node” you may have found, but I digress.


    Not uncommon to have great accuracy with virgin brass. My theory is it softens pressure spikes, and then necks are perfect. Id be quite happy to toss brass after the first firing, but that shit is expensive. I’ll go be poor somewhere else now.
     

    Steel head

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    Some people do still neck size like my brother from another mother @Steel head. He got shorted a chromosome though I think. 👊🏻

    Gosh, it would take a lot of rounds to discern .1 gr in a case that big imo. And of course any change in temp with RL26 would blow you right out of any “node” you may have found, but I digress.


    Not uncommon to have great accuracy with virgin brass. My theory is it softens pressure spikes, and then necks are perfect. Id be quite happy to toss brass after the first firing, but that shit is expensive. I’ll go be poor somewhere else now.
    Only reason for and benefit of neck sizing is to be lazy.
    It’s great on my 260 as I know it very well with tons of experience and data.
    It’s just a critter and steel blaster.



    I always full length size my magnums for ELR or for important tasks like hunting and competition.

    Your lying to yourself if you think neck sizing is giving you anything more than time savings and you better be using a Lee collet for that because most times bushing neck sizers suck.

    In saum sized cases I just work in .2-.3 increments.
    Less is silly.

    There’s going to be a noticeable difference in required loads between virgin and neck sized brass.
    More so than the common virgin vs full length sized powder adjustment.
     
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    Milo 2.5

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    We all have our methods, I am not one to test only a certain number of pcs of brass. Why, I believe your baseline is lost. I think your issues all stem from neck tensions, you cannot duplicate now what you once had.
    Annealing by itself is not a cure, you soften your brass when you do it, adjustments sometimes need to be made unless after every firing is your regimen.
     

    larryh128

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    Some people do still neck size like my brother from another mother @Steel head. He got shorted a chromosome though I think. 👊🏻

    Gosh, it would take a lot of rounds to discern .1 gr in a case that big imo. And of course any change in temp with RL26 would blow you right out of any “node” you may have found, but I digress.


    Not uncommon to have great accuracy with virgin brass. My theory is it softens pressure spikes, and then necks are perfect. Id be quite happy to toss brass after the first firing, but that shit is expensive. I’ll go be poor somewhere else now.
    I do tenth of a grain all the time. Normally it's super easy to fine tune a load. Often a tenth change will move 3-4 inches from the last 4 rds that were basically connected and you pretty well know the barrel doesn't like that much. I've already done a wider ladder and this is basically fine tuning. As to loading regiment, I anneal, body size, full length size with .002 shoulder set back, clean primer pockets, Trim, ID / OD champher. Same every time.
     

    larryh128

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    We all have our methods, I am not one to test only a certain number of pcs of brass. Why, I believe your baseline is lost. I think your issues all stem from neck tensions, you cannot duplicate now what you once had.
    Annealing by itself is not a cure, you soften your brass when you do it, adjustments sometimes need to be made unless after every firing is your regimen.
    It could very well be the neck tension. I turn all my necks to .013 and I'm going to mic the 10x fired cases tonight to see if that figure is still the same or if they have thinned.
     

    Milo 2.5

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    It could very well be the neck tension. I turn all my necks to .013 and I'm going to mic the 10x fired cases tonight to see if that figure is still the same or if they have thinned.
    Well ok, but say you find something, are you set up to make adj? Do you use bushing dies, or have various mandrel sizes, at some point, one size fits all may not work.
     

    larryh128

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    Well ok, but say you find something, are you set up to make adj? Do you use bushing dies, or have various mandrel sizes, at some point, one size fits all may not work.
    No I don't use bushing dies, I've never seen the need for what I'm doing so far. I understand what you are saying and it's very possible. The Gap brass is made by Hornady and I really have no experience with it prior to this. Normally I'm using either Lapua or ADG brass and haven't seen this with either.
     

    larryh128

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    Well ok, but say you find something, are you set up to make adj? Do you use bushing dies, or have various mandrel sizes, at some point, one size fits all may not work.
    Yes, I would adjust, if I find it's thinned dramatically I will literally shit can it.
     

    Milo 2.5

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    No I don't use bushing dies, I've never seen the need for what I'm doing so far. I understand what you are saying and it's very possible. The Gap brass is made by Hornady and I really have no experience with it prior to this. Normally I'm using either Lapua or ADG brass and haven't seen this with either.
    The brand of brass may very well be a big portion of your issue. Fire some new and let us know, you were going in the right direction with that thought.
     

    Supersubes

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    Only reason for and benefit of neck sizing is to be lazy.
    It’s great on my 260 as I know it very well with tons of experience and data.
    It’s just a critter and steel blaster.



    I always full length size my magnums for ELR or for important tasks like hunting and competition.

    Your lying to yourself if you think neck sizing is giving you anything more than time savings and you better be using a Lee collet for that because most times bushing neck sizers suck.

    In saum sized cases I just work in .2-.3 increments.
    Less is silly.

    There’s going to be a noticeable difference in required loads between virgin and neck sized brass.
    More so than the common virgin vs full length sized powder adjustment.
    I know, Im just giving you shit.
     
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    918v

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    New brass is different than fired brass. First, it is smaller. Factory brass has not yet expanded to seal a chamber. Sizing a fired case seldom brings it down to factory dimensions. This difference in dimensions causes a difference in combustion, velocity, blah, blah, blah. Second, a factory case is not under stress in the areas that matter- neck and shoulder. Why? Because factory cases are annealed at the neck and shoulder after having been formed to their final dimension. Most people anneal their brass before sizing in order to make sizing consistent. But factory cases are annealed after forming. The difference is the brass in a factory case is relaxed while the brass in the sized case is under stress. Again, this alters combustion, velocity, etc. Third, factory cases are coated in some sort of wax which makes bullet seating easier. Fired/annealed/sized cases are not. Therefore, bullet release is different and so is point of impact.

    You will never be able to return the case to it‘s unfired state. All you can do is make your process consistent and maybe, if you’re competent, make your case necks optimal for bullet release.
     

    Rocketmandb

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    New brass is different than fired brass. First, it is smaller. Factory brass has not yet expanded to seal a chamber. Sizing a fired case seldom brings it down to factory dimensions. This difference in dimensions causes a difference in combustion, velocity, blah, blah, blah. Second, a factory case is not under stress in the areas that matter- neck and shoulder. Why? Because factory cases are annealed at the neck and shoulder after having been formed to their final dimension. Most people anneal their brass before sizing in order to make sizing consistent. But factory cases are annealed after forming. The difference is the brass in a factory case is relaxed while the brass in the sized case is under stress. Again, this alters combustion, velocity, etc. Third, factory cases are coated in some sort of wax which makes bullet seating easier. Fired/annealed/sized cases are not. Therefore, bullet release is different and so is point of impact.

    You will never be able to return the case to it‘s unfired state. All you can do is make your process consistent and maybe, if you’re competent, make your case necks optimal for bullet release.

    I was waiting for you to also bring up the "if brass is over annealed, it gets hosed" point.

    OP, how are you annealing?
     

    larryh128

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    I have a machine I built, uses a propane torch. Adjust flame, dial in speed you want. Works good. It may not be a brass issue, it could be that I hit the upper limit of what the barrel likes. I don't have issues with brass / accuracy in the other calibers I load and this might not be either. My original post was just looking to see if anyone had seen brass go south in an instant. The firing before these cases held sub 1/4 moa.
     

    918v

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    Why not section one of them to see if they are about to let go. In my testing the cases that are about to separate produce fliers. I extract and look and see that dreadful line.
     

    larryh128

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    I didn‘t want to offend.
    It's not over annealed. I'm going to re shoot those 6 with new brass and see what they do as soon as the wind stops howling. I doubt there is much wax left on the new cases. I full length size and tumble before initial loading. Plus they have been neck turned.
     

    larryh128

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    Why not section one of them to see if they are about to let go. In my testing the cases that are about to separate produce fliers. I extract and look and see that dreadful line.
    Good idea, I'll do that. Separation is something I don't ever have but worth looking at. As I said, I don't have experience with Hornady brass.
     

    GONE BAD

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    Interesting thread.
    A lot of the post and replies, to me, seem very informative.
    Lots of information.
     

    larryh128

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    I sectioned the case with the highest charge. No indication of case separation. Will ck the neck thickness with the proper mic tonight.
     

    918v

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    Then it’s gotta be a new brass/used brass thing. New cases have never behaved the same as 1x+ for me.
     

    larryh128

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    I miced out the fired case necks that I'm discarding. All still miced. .013. Loaded up the exact charges on new brass and when wind goes to a 0 factor will give them a try.
     

    larryh128

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    Shot same charge with a new case and old case. Old case printed 3" high and about 1" left @300 yds. New case shot into about an 1" group with 5 loads that stepped up .1 per charge. Basically each round touching/cutting the previous round. This has been pretty normal as at this point I'm strictly fine tuning the load as I've found the small charge are I want to test previously. It appears that the brass has seen the end of it's useable form. After this I'm discarding after about 6 loadings.