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Thread: Nosler Partition question

  1. #1

    Nosler Partition question

    Tried to post this yesterday and the site bombed out on me in some strange way so here we go again, sorry if it appears twice somewhere as the first one might have gone through a wormhole only to appear again in due course.

    I've been loading 150 grain Hornady Spire Points in my 308W. The load is giving me good accuracy and 3000fps with no sign of any pressure and some cases are on 10+ loadings with no problems. I'm loading 49 grains of Reloader 15 which is a book max load according to Alliant.

    After over a year of waiting I've finally managed to get he 150 grain Nosler Partitions that I wanted to try out but my supply is fairly modest and I'm not likely to get any more any time soon so I want to use as few as possible in load development.

    Has anyone, and I know it is a pretty remote chance, gone from shooting Hornady Spire Points in 308 with RL15 to the Partitions? If so any guidance on how you had to change the load etc.?

    My plan, and I'm open to comments, is to load single rounds in 1 grain intervals from 42 to 46 grains as this is the load Nosler print for this bullet. If there are no signs of pressure then I may work up further in half grain intervals but never exceeding the Alliant 49 grain max for a 150 grain bullet. I will then load up 5 rounds at intervals starting from what I decide is my max load downwards and shoot them for groups with the hope that one of them will shoot well for me without too much messing about. To be honest my Blaser tends to shoot everything reasonably well so load development for it hasn't been a big problem but I'd like to try and keep some of the decent velocity I'm getting and also get accuracy around the 1 inch mark with accuracy being the priority.

    All thoughs and suggestions are gratefully received.

  2. #2
    First, "No", I haven't, or don't recall, going from Hornady 150s to Nosler 150-grain Partitions.

    That said, in more than 40 years of reloading, I have only devoted more time to the 7mm caliber than I have to the .308 Winchester cartridge. That's NOT to suggest that I am an "expert" and expect you to take my following comments as "gospel". Rather it simply qualifies "some guy on the internet" comments. And, being "some guy on the internet", I could just as easily be lying about "40 years of reloading". The bottom line is: Take what sounds reasonable and TRY IT FOR YOURSELF. THOSE results are the only ones that matter.

    That said, I would STRONGLY urge you NOT to START by 'fiddling with' the charge. KEEP THE CHARGE. I believe you are most likely to get satisfaction with the new bullet by "fiddling with" seating depth. Start with the bullet about 0.015" off the lands. Then load 4 or five rounds each with seating depths that increase in 0.030" increments back to about 0.150" off the lands. It is HIGHLY LIKELY that somewhere in that interval from 0.015" off-the-lands to 0.150 off-the-lands, you will find a precision (accuracy) 'sweetspot'. Once found, you can 'experiment' around that sweetspot altering both charge and seating depth in SMALL increments if you like.

    Best of luck,
    Paul

  3. #3
    Quote Originally Posted by gitano View Post
    That said, I would STRONGLY urge you NOT to START by 'fiddling with' the charge. KEEP THE CHARGE. I believe you are most likely to get satisfaction with the new bullet by "fiddling with" seating depth. Start with the bullet about 0.015" off the lands. Then load 4 or five rounds each with seating depths that increase in 0.030" increments back to about 0.150" off the lands. It is HIGHLY LIKELY that somewhere in that interval from 0.015" off-the-lands to 0.150 off-the-lands, you will find a precision (accuracy) 'sweetspot'. Once found, you can 'experiment' around that sweetspot altering both charge and seating depth in SMALL increments if you like.

    Best of luck,
    Paul
    Caorach, as a relatively new reloader, only two years, but having done a lot of reading on reloading, I too would recommend you to alter seating depth/ distance to the lands before you alter any powder charges. With the caveat that the powder charge you use is within safety margins.

    I have found distance to the lands far more critical than powder charges, every time.

    ft
    Blindness to suffering is an inherent consequence of natural selection. Nature is neither kind nor cruel but fiercely indifferent.

  4. #4
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    Quote Originally Posted by caorach View Post
    Tried to post this yesterday and the site bombed out on me in some strange way so here we go again, sorry if it appears twice somewhere as the first one might have gone through a wormhole only to appear again in due course.

    I've been loading 150 grain Hornady Spire Points in my 308W. The load is giving me good accuracy and 3000fps with no sign of any pressure and some cases are on 10+ loadings with no problems. I'm loading 49 grains of Reloader 15 which is a book max load according to Alliant.

    After over a year of waiting I've finally managed to get he 150 grain Nosler Partitions that I wanted to try out but my supply is fairly modest and I'm not likely to get any more any time soon so I want to use as few as possible in load development.

    Has anyone, and I know it is a pretty remote chance, gone from shooting Hornady Spire Points in 308 with RL15 to the Partitions? If so any guidance on how you had to change the load etc.?

    My plan, and I'm open to comments, is to load single rounds in 1 grain intervals from 42 to 46 grains as this is the load Nosler print for this bullet. If there are no signs of pressure then I may work up further in half grain intervals but never exceeding the Alliant 49 grain max for a 150 grain bullet. I will then load up 5 rounds at intervals starting from what I decide is my max load downwards and shoot them for groups with the hope that one of them will shoot well for me without too much messing about. To be honest my Blaser tends to shoot everything reasonably well so load development for it hasn't been a big problem but I'd like to try and keep some of the decent velocity I'm getting and also get accuracy around the 1 inch mark with accuracy being the priority.

    All thoughs and suggestions are gratefully received.
    My first thought is; Are you using boattail or flat base Hornady Spire points?

    I only ask because it occurs to me that 3000fps with a 150grain Hornady from a .308 case seems near to full pressure velocity and not much backed off.

    Depending on the answer to my "first thought, it then seems to me possible, that: If you go from the short bearing surface of the boat tails to the longer bearing surface of the partitions (which have "flat bases) you might see an increase in pressure. Of course, that may or may not be a significant issue. You'll have to judge for yourself.

    For what it's worth; I'd follow usual practice and work up to a new load. Sorry if that uses more bullets than you'd like but then I'm a fairly cautious person when it comes to reloading.

  5. #5
    I should also add that as you seat the bullet deeper, the max chamber pressure will rise. If you are 'near max'
    book max load according to Alliant.
    AND 0.015" off the lands with your existing load, you will NOT be able to seat the bullet to 0.150" off the lands without REDUCING the existing charge.

    It may be that you are currently WAY off the lands. In which case, seating 'out' to get to the 0.015" off the lands will LOWER the pressure, and seating deeper to get to 0.150" off the lands MAY be possible without changing the charge.

    What should be clear, is that you need to know as precisely as possible where your bullet's ogive is relative to the lands on your rifle. Put another way, you need to know your rifle's chamber length as precisely as possible. The more precisely you know that, the more precisely you will be able to size your cartridges relative to the chamber.

    If you are unaware of how to get precise measurements of you chamber, be advised that there are many ways to 'skin that cat'. Just ask, and you'll get plenty, ranging from "free" to "expensive".

    Regards,
    Paul

  6. #6
    By all means, fiddle with the charge! Back it off to minimum and work your way up as is proper when changing components. My 2 Cents worth.~Muir

  7. #7
    Back it off to minimum and work your way up as is proper when changing components.
    I'll sidestep the "proper" component of the above comment, and stick to some simple math in the context of caorach's original comments. Let me list the ones that I was paying close attention to:

    1) After over a year of waiting I've finally managed to get he 150 grain Nosler Partitions that I wanted to try out,
    2) but my supply is fairly modest and I'm not likely to get any more any time soon so I want to use as few as possible in load development.
    3) I'm loading 49 grains of Reloader 15...The load is giving me good accuracy
    4) I've been loading 150 grain Hornady Spire Points.
    5) The load is giving me good accuracy and 3000fps with no sign of any pressure
    6) My plan, and I'm open to comments, is to load single rounds in 1 grain intervals from 42 to 46 grains as this is the load Nosler print for this bullet. I may work up further in half grain intervals but never exceeding the Alliant 49 grain max for a 150 grain bullet. I will then load up 5 rounds at intervals starting from what I decide is my max load downwards and shoot them for groups with the hope that one of them will shoot well for me without too much messing about.

    Using 42 grains as the minimum, loading 5 rounds per 1-grain interval, the FIRST iteration will be 5@42, 5@43, 5@44, 5@45, and 5@46 for a total of 25 bullets and 1100 grains of powder used. Assuming that 46 grains wasn't a problem, and it won't be if the cartridge overall length is kept the same as it was for the Hornadys, we'll continue on up in 0.5-grain increments. That's 5@46.5, 5@47, 5@47.5, 5@48, 5@48.5, 5@49 for a total of 30 bullets (you've just emptied that 50-bullet box AND 5 more) and used ANOTHER 1432.5 grains of powder. To that you can add however many 5-shot groups he would consider shooting assuming he had any bullets left. That's a total of 55 bullets and 2532.5 grains of powder. That's 110% of a 50-bullet box of Partitions, and 36.18% of a pound of powder. He knows more what he's paying for bullets and powder than I do, so he can "do the math" on what that particular "load workup" would cost him, not considering that he might have to wait another year for another box of bullets.

    The results will be much less conclusive, but let's assume instead of 5 shots each, he only uses 3 shots each. The initial run from 42 to 46 grains will only use 15 bullets and 660 grains of powder. In the second run up, he'll use 18 bullets and 859.5 grains of powder. The totals are 33 bullets and 1519.5 grains of powder. He'll still have 17 bullets left and will have used only 21.70% of a pound of powder. At that point, he'll start working "down" from the "max load" in hopes of finding a precision (accuracy) 'sweetspot'.

    Or...

    He can load 4 (I picked the middle point for expediency - anyone can do the math 'up' or 'down') bullets each at 0.015", 0.045", 0.075", 0.105", 0.135" and 0.165" off-the-lands seating depths. The charge would all be the same that he is currently using, 49.0. The total number of bullets would be 6x4=24, and the total powder used would be 24*49=1176 grains of powder (16.80% of a pound). WITHOUT QUESTION there WILL be a PRECISION "sweetspot" in that batch of round fired. Furthermore, there is NO "danger" of high pressure if his initial test is at the COAL he is currently using. From that point, he can go up and/or down in seating depth, always vigilant for excessive pressure - which is NO DIFFERENT than he would have to do if he "fiddles" with charge. Once a PRECISION sweetspot is found, he can "play around" with velocity as long as he has bullets and powder and time to play around.

    Now, ALL of that said, I honestly and truly couldn't care less what procedure Caorach chooses to use. It matters not one whit to me. NONE. However, what does matter to me is the 'old saying' that insists that "Whenever you change a component you have to start ALL OVER from scratch at the lowest charge."

    Who wrote that first? POWDER AND BULLET MAKERS!

    Who benefits from that approach? POWDER AND BULLET MAKERS!

    Is that procedure "safe"? Of course. So is not shooting at all, and this procedure is no less unnecessarily cautious as to be as absurd as not shooting a gun at all because that would REALLY be "safe".

    If, as CAORACH HIMSELF ASSERTS, he has no signs of pressure after LONG use of this charge, HE WILL NOT HAVE ANY RISK OF ELEVATING PRESSURES BEYOND "SAFE" LEVELS WITH A BULLET OF THE SAME WEIGHT. To "go back to zero" is an unnecessary waste of STATED (no assumption on my part) precious resources.

    You'll get plenty of advice, Caorach, mine is no "better" on its face than anyone else's about which you have no qualifying information. YOU need to decide what YOU are comfortable doing, and stay within your own "comfort zone". YOUR SAFETY is YOUR responsibility. Imagine how absurd it would sound in the hospital's emergency room if you were telling the doctor that "It wasn't my fault. I was just doing what some guy on the internet told me to do".

    The good news is that there is a very simple test for you to conduct to test the "safety" of using your current "safe-pressure" charge with a new bullet: Load half a grain down, the SAME cartridge OAL, and fire one off. It would be difficult to imagine that ANYONE could believe that the "bearing surface" of these two bullets would be SO different that the pressure would rise dangerously. If that "test" doesn't satisfy you that the 150 Partition can be considered "safe" with your Hornady loads, then you'll need to "go back to zero" and start all over.

    My intent with the above "test" is NOT to "prove" ANYTHING. I have nothing to prove. Instead, it is the recognition that in order for us to get ANYTHING useful from the internet, we have to 'operate' within our own personal "comfort zones", AND... The only way to define our "comfort zones" is with experience. The above suggested "test" is a way for you to get some relevant personal experience with no risk.

    All the best,
    Paul

  8. #8
    Even though that is "a lot of words", I have a few more that may be relevant.

    Looking at Nosler's reloading manual (the manufacturer of the bullet in question) fifth edition, page 301:

    Their load data listed for the .308 Winchester cartridge lists SIX DIFFERENT BULLETS ranging from Solid Base Ballistic Tips, to Combined Technology Fail Safes and more importantly, they range in weight from 150 to 155 grains. IN THE BULLET MANUFACTURER'S OWN MANUAL, neither DESIGN nor weight CHANGES of 5 grains warrants SEPARATE LOAD DATA. In other words, ALL the 150 to 155 grain bullets regardless of design get the SAME suggested charge recommendations. That should be sufficient "evidence" that within a given weight, changing "design" doesn't warrant "going back to zero" to work up new loads. If the bullet manufacturer and all their lawyers don't care, it seems "safe" to me if I don't care.

    It STILL boils down to an individual's level of comfort. If you are acting outside your comfort zone, you are on shaky ground.

    Best of luck with your load workup,
    Paul

  9. #9
    You sure are a wordy guy, Paul, but writing a lot doesn't make you right.

    Reducing loads when changing components is still a standard that most powder makers and industry folk prescribe to. This is an excerpt from the Hodgdon #27 reloading manual, borrowed from the pages of the Lee Manual Vol II. Seems that manufacturers think that variations in same-LOT components can bring about significant changes in pressures, and perhaps illustrates why switching components entirely at maximum charge levels might add to the risk.
    Click image for larger version. 

Name:	Hodgdon 27 Warning.jpg 
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    ~Muir

  10. #10
    coarach

    Why not try a ladder test? I have read a couple of links on this and attach one.

    Long-Range Load Development

    Rgds JCS

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