Finding the maximum charge

[Wheeljack]

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 could 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.  

Edited May 3, 2017 by Wheeljack

[Alaskapopo]

If you want a hot 147 grain load look to the Vitavory manual and 3n38. makes major.

[kneelingatlas]

How about a little background, what are you looking to accomplish?  Shooting USPSA competition?  Just a hot load for target practice?

 

Like Pat said above, 3N38 is the best powder available for hot 9mm loads with the lowest chamber pressure, the max 147gr load listed in their load manual propels a Hornady XTP 1,207fps

 

http://www.vihtavuori.com/en/reloading-data/handgun-reloading/9-mm-luger.html

[Wheeljack]

I just got some Win 572 powder and I'm looking for load information.  I looked into the SAAMI manual and Hodgdon data.  Hodgdon gives info for the XTP bullet with a 4" barrel.  What confuses me (it's not hard to do) is why the max load shows velocity under SAAMI max and pressure under SAAMI max.  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.

[superdude]

The powder companies don't say why their load data stops well below the SAAMI pressure limit. We're left to guess why. It might mean that adding another 0.1 grains pushes it past the limit, or is compressed (which might affect powder performance), or ..... who knows what. 

 

Max velocity within max pressure limits varies with every gunpowder, so using velocity as a measure of pressure is not wise since one can come to the wrong conclusion about pressure, and since pressure is a safety issue, it's the most important variable.  See Hodgdon's data for 700-X and the 147 grain XTP as an example. It won't get near the SAAMI nominal velocity without going way over the pressure limit. 

 

Your way of thinking about the charge weight/velocity/pressure issue has some validity, but since Hodgdon does not provide pressure curve data for their powders, we simply don't know what happens when you increase the charge weight past their recommended levels. There are simply too many variables that can affect the results - bullet type, OAL, and so on. That's why it's hard for us to speculate to much.  Some powders are more-or-less linear in their response to charge weight increases over the range we normally use them.  Some powders might behave in a non-linear fashion, and pressure could quickly rise to dangerous levels. We simply don't know if they don't provide that information.

 

You could ask Hodgdon. They might have some good advice for you.  Sometimes powder company answers are canned (don't do that!) and sometimes they are very happy to share more detailed information.  

[Jim Watson]

I think that when a powder tops out below SAAMI MAP, it is because it is not very consistent in that application and the statistical massaging they do would put it over the MPSM or MPLM. 

[kneelingatlas]

2 hours ago, Wheeljack said:

I just got some Win 572 powder and I'm looking for load information.  I looked into the SAAMI manual and Hodgdon data.  Hodgdon gives info for the XTP bullet with a 4" barrel.  What confuses me (it's not hard to do) is why the max load shows velocity under SAAMI max and pressure under SAAMI max.  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.

 

I'm a little lost, the relationship between velocity and pressure is going to be unique among different powders and not all powders will have a useful range which reaches the SAAMI max pressure for the cartridge.

 

If I understand your goal it's to find the most accurate load using 147gr XTPs and 572 powder, is that right?

[Hi-Power Jack]

6 hours ago, kneelingatlas said:

  the max 147gr load listed propels a Hornady XTP 1,207fps

 

Wow !!!

 

That's a PF of 177 - awesome for a listing in a reloading manual     

 

Anyone dragging their heels on reloading 9mm Major might

want to consider that this company, despite all their lawyers' advice,

lists a PF 177 load for 9mm Major    

[kneelingatlas]

That's why 3N38 is the bee's knees Jack!

 

They even have a book load for 9x21 you can load in 9x19 and make major with 115gr bullets:

 

9.4gr under a 115gr JHP @1.161" for 1,483 fps (171 PF)

[Hi-Power Jack]

43 minutes ago, kneelingatlas said:

That's why 3N38 is the bee's knees Jack!

 

I should know from reading your postings for the past few years,

 

BUT, is 3n38 Your preference for 9mm Major?

[kneelingatlas]

I actually have a stash of SP2 which is a French powder not currently available in the US, but the load data is interchangeable with 3N38.  When I run out of SP2, I'll be switching to 3N38, in my mind there is no better powder for 9 major, it also works great in 38 super.

Edited May 4, 2017 by kneelingatlas

[Hi-Power Jack]

No problem loading 9.4 grains into a 9mm case - no powder

spillage during the reloading process?

[kneelingatlas]

5 hours ago, Hi-Power Jack said:

No problem loading 9.4 grains into a 9mm case - no powder

spillage during the reloading process?

 

As long as you don't run the press like a drunken sailor you'll be fine 

 

I load on a case feed, bullet fed 650 and if I load at a pace of 5-6 min per hundred rounds I won't spill any, if I load faster bullets start falling over and powder flips out.

[Hi-Power Jack]

Guess my next powder purchase is going to be 3N38.

 

Thanks    

[Wheeljack]

On 5/3/2017 at 3:11 PM, kneelingatlas said:

 

I'm a little lost, the relationship between velocity and pressure is going to be unique among different powders and not all powders will have a useful range which reaches the SAAMI max pressure for the cartridge.

 

If I understand your goal it's to find the most accurate load using 147gr XTPs and 572 powder, is that right?

At this point, I was just interest in why the Hodgdon maximum load seemed a little light.  So I guess you could say I'm looking for the safe maximum load for 572 powder, and not the +P load.  Then I will back off and start looking for the most accurate load. 

Edited May 5, 2017 by Wheeljack

[Wheeljack]

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.

[kneelingatlas]

SAAMI says the max pressure is 35,000psi, so why is Winchester telling you the max charge weight is 4.1 if it only yeilds 32,200psi?  Does this sum up your question?

 

I suspect the answer to that is Winchester uses some criteria other than pressure and velocity in determining their recommended loads and that beyond 4.1gr the results no longer met one or more of those criteria (perhaps accuracy or consistency).

[CZ85Combat]

For the gun you are using Win 572 is not a good choice.  Win 572 is a slow burning powder and with a 3.42" barrel a lot of powder will be burning out the end of your barrel.  You can use a powder burn chart to get a rough idea of the powder that would work will with your gun.  All powder burn rate charts are a little different so take it for what it is worth.  On this chart you want to look for a powder in about #28-#38 +/- range.

http://www.wwpowder.com/PDF/Burn Rates - 2015-2016.pdf

Edited May 5, 2017 by CZ85Combat

[Wheeljack]

And I was told the Win 231 I was using was to fast burning.   Do you ever get the feeling you can never win?

But, thanks.

[TDA]

42 minutes ago, Wheeljack said:

And I was told the Win 231 I was using was too fast burning. 

It may be, on a different chart...

[lgh]

On 5/5/2017 at 4:11 PM, kneelingatlas said:

SAAMI says the max pressure is 35,000psi, so why is Winchester telling you the max charge weight is 4.1 if it only yeilds 32,200psi?

If you measure the pressure multiple times at the same 4.1 charge weight, you will not always get 32,200. That never happens in the real world. There is variation and they know it. They are accounting for that variation and plugging in a safety factor.

[kneelingatlas]

1 hour ago, lgh said:

If you measure the pressure multiple times at the same 4.1 charge weight, you will not always get 32,200. That never happens in the real world. There is variation and they know it. They are accounting for that variation and plugging in a safety factor.

 

I agree, I was just guessing at the OP's motivation for starting this thread.

 

[Wheeljack]

I like to experiment.  But also, when I do something wrong, I learn a lot from you guys.   Well, I have some 572 to burn up and then I think I'll be looking into something like Unique or Power Pistol.   Thanks.