Finding your maximum load

Discussion in 'Reloading' started by Wheeljack, May 2, 2017.

  1. Wheeljack

    Wheeljack

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    SAAMI lists the 9mm round with a 147gr bullet. The old standards (1993) listed a Jacketed 9mm but the new 2015 standards do not mention bullets type. Lead, plated, jacketed or what ever. What they do list is a velocity and pressure. Actually 3 pressures, but I'll stick to the MAP or maximum average pressure. For a 147gr bullet they list a velocity of 985fps and a pressure of 35,000psi. Now it seems from that, I would work up a load for my 147gr bullet, whatever kind, to a maximum of 985fps and 35,000psi. Hodgdon data list a 147gr XTP, loaded with 4.1gr of 572, with a velocity of 954 and a pressure of 32,200psi and calls this a maximum load.
    Wouldn't you think that you could up the powder charge a little to get to the 985fps level for a maximum load? There are obviously other factors to consider, but what are they and is there any place to find that information.
     
  2. Benchrst

    Benchrst Ban Hamster

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    Numerous, and that's for a single caliber.

    For the Hodgdon load it could have been: Case was at 100% capacity; Increased powder yielded no increase in velocity; Powder got spikey (not saying 572 does); etc, etc.
     
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  3. fredj338

    fredj338

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    The issue with working over max. Many powders stop linear pressure movement & can spike. Its more prevekanr with faster powders but can happen with slower ones. Supposedly BlueDot does this in certain calibers. So can you exceed max, maybe, every gun is diff.
     
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  4. Wheeljack

    Wheeljack

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    My Glock is rated for +P ammo pressure of 38,500psi. Hodgdon's 4.1gr maximum listed a pressure of 32,200. The shell holds 10.4 gr of 572 powder, so there is no compression of the powder. I just have not been able to find out why powders are not safe below SAAMI pressures and what happens if you load over the listed maximum.
     
  5. Puros_bran

    Puros_bran

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    The book maximum may not be your particular firearms maximum. Your particular firearm may have a lot higher or just as likely a lot lower pressure limit than a book maximum. The book is guidance, but not the final authority. The theory is you start low and build your charge up looking for pressure signs. Always err on the side of safety. I seldom load anywhere near maximum. If you aren't hunting or trying to reach some competition's Major/Minor power cutoff there's really no sense in it.
     
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  6. Benchrst

    Benchrst Ban Hamster

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    Internal ballistics are not entirely understood, therefore unpredictable. ie, I don't think there's a simple answer to your question.

    Reloading manufacturers load for a goal - usually safe, consistent performance across a broad range of variables. They scrutinize and publish, and we have what we have.
     
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  7. WeeWilly

    WeeWilly

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    If you want to drive a 147gr bullet to 985fps and can't find any of your favorite manufacturers load data to accomplish that within their maximums, you can use Western Powders load data for some of their powders and load to +P pressure, they have a number of options that will do that and better.

    http://blog.westernpowders.com/wp-content/uploads/2016/02/WesternLoadGuide1-2016_Web.pdf

    PS - 572 is a relatively new powder, so likely the only published data will come from Hodgdon. Eventually Speer and Hornaday might test it with their bullets and you will have another data point on how high you can go. Speer tend to be the hottest, with the occasional nod to Hornaday in some calibers.
     
    Last edited: May 3, 2017
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  8. fredj338

    fredj338

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    You can make any powder work safely, the trick is at what pressure levels. Just keep in mind that as pressures climb they often are not linear. So just over nax may be way over max.
    Use a chrono, work up in 1/10gr increments. Pay attention to vel, it should increase in a linear fashion as you add powder. If it spikes OR flattens, back off from that, you are likely there.
     
    Last edited: May 3, 2017
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  9. Wheeljack

    Wheeljack

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    Sounds good. I will use a chrono and stay under SAAMI maximum fps. I'll run a few different loads and look for the one with the tightest group. It's not that I want to use the maximum loads, it's that I am trying to understand them. I'm sure the powder manufacturers could give us more information, if it wasn't for their lawyers.
     
  10. TN.Frank

    TN.Frank "Don't Tread On Me!"

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    I consider book max on 9x19mm to be safe in firearms that are rated for +P or +P+ ammo like Glocks, S&W M&P's, Sigs, H&K's ect. I'd not want to fire them in something like a Taurus or Hi-Point where the quality control may be lacking. Also, I've seen several "Max" loads using the HS-6 I used in my 147gr XTP handload test so just how are they getting their so called "Max"? Is it in a certain firearm or a pressure barrel or are they just going for a certain velocity and calling that "good to go"? The HS-6 load I fired worked fine, no real pressure signs, spot on as far as velocity goes comparing to chrony and book listed velocity and it was a Standard Pressure load so even if it went over a bit it still would only be a +P load at the most so I consider it safe in my S&W's to shoot. Of course your mileage may vary, I've been handloading for some 35 years and have kind of gotten a "feel" for it. Someone new to handloading would definitely want to start with a less than max load and work their way up or if you're using a powder you've not loaded before and don't know how it'll react then it's also wise to start below max and work your way up.
     
  11. WeeWilly

    WeeWilly

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    I have loaded 572 over Hodgdon max load and it was pretty well behaved using 124gr jacketed slugs. It is sufficiently slow to likely get where you want to go without breaking anything, but as Fred said, work up slowly and inspect every case.

    Do not use any powder substantially faster burn rate wise and assume you can get to 985fps safely, unless it is tested.
     
  12. fredj338

    fredj338

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    Keep in mind when chasing book vel, test platforms vary, sometimes a lot. If you are shooting a 3 1/2" gun, you arent safely sniffing vel of a 5" gun. Understanding what the chrono tells you is vital when leaving book data behind.
     
    Last edited: May 4, 2017
  13. ss30378

    ss30378

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    Warning don't replicate my load data without careful workups and a gun built to handle 9mm major loads!!!

    Loads below were fired from a compensated 17l with a 6.5" barrel so don't expect to match the numbers from a short barrel.

    In my 572 post I put up a few months back I ran a 147 grain bullet up to 5.7g of 572 for 1270fps and velocity and case head expansion was nearly linear all the way from 4.0g to 5.7g. 572 does very well in the small 9mm case as well as bigger straight walled cases.

    The only erratic pressures shown were in the bottleneck 357sig when getting to well beyond max loads.
     
  14. Wheeljack

    Wheeljack

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    I'm not going to those levels, but it's nice to know that 572 seems to be a well behaved powder. I hope to get to the range soon and will report back.
     
  15. DWARREN123

    DWARREN123 Grumpy Old Guy

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    Also remember that max may not be the most accurate load or it may be.
    Do you just want fastest or most accurate?
     
  16. Wheeljack

    Wheeljack

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    Just curious about the max. That being the max within the average SAAMI definition and not the +P range. SS30378 did some higher loads that gave me more information. He went up to 1240fps, which is more than I am looking for. I have a shorter barrel for one thing. But he said he found the powder reacted in a linear fashion with no spikes. That said, I was just curious enough to try to get to 985 or close enough that I can judge what the load will do. I will not try for 985 because of my shorter barrel. The velocity in a 3.5" barrel may be 28fps slower, but a Polygonal barrel may be 22fps faster than a 4" barrel. My Glock barrel is about a half inch shorter than that used for the Hodgdon data, so I estimate the maximum fps may be about 979fps for a Glock 26. So if I load 3.6g and 3.8 gr and 4.0 gr I will get a feel for how fast an even larger charge will be without having to load it. If 4.0 gr gives me 962fps then I can figure 4.1 will give me 979. I won't have to load to 4.1 if I don't want to, but just say I'm close enough. Looking at the Lyman manual, it seems there has not been a maximum charge that was ever the most accurate. So, I will start with the 4.0gr load and go lighter with more loads until I find one I think is the most accurate. All this may not be practical, it's just that I want to know.
     
  17. Wheeljack

    Wheeljack

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    With my 147gr Xtreme plated bullets, in my Glock 26 with a 3.42" barrel, an OAL of 1.150....
    Win 572 at 3.8gr gave me an average fps of 843; 4.0gr 858 and 4.2gr 872fps. The maximum fps with 4.2gr was 894.
     
  18. DWARREN123

    DWARREN123 Grumpy Old Guy

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    Reloading and finding good loads is much fun, in my opinion!
     
  19. fredj338

    fredj338

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    Glock bbls are really not any faster than conventional rifled. Individual bbls will vary more than what you might get in a Glock poly bbl. Slower powder will show greater loss per inch than faster powders, but 25-30fps per inch is a good benchmark.
     
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  20. WeeWilly

    WeeWilly

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    It has been my experience that most of the Glock barrels I have tested were actually a little slower than another brand barrel of the same length. I never starting noticing it until Fred pointed it out that they weren't faster. :)
     
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