357mag/158gr powder recommendation

[GeoDudeFlorida]

The very high muzzle pressures of AA7, AA9 and Blue Dot indicate that lots of flash/bang are expected. AA7 and Blue Dot give essentially the same performance as AA9 while using 10% less powder.

There we go.

 

[fxvr5]

With numbers from fxvr5, I ran a Quickload (QL) table with the powders from the OP.

Given the desire to use a specific bullet with no known actual test data, QL is probably as good as you are going to get for predicting performance and pressures. I used the default QL max recommended chamber pressure when I ran the table. This should be safe and going over it puts you more at risk of exceeding the SAAMI limit given that this is not actual test data. Starting below the values shown and working up is recommended.

QL does not account for cylinder gap, I typically subtract 50 fps from the prediction. The QL input for barrel length is muzzle to breech, so it includes the cylinder.

The very high muzzle pressures of AA7, AA9 and Blue Dot indicate that lots of flash/bang are expected. AA7 and Blue Dot give essentially the same performance as AA9 while using 10% less powder.

Cartridge          : .357 Magnum (SAAMI)            
Bullet             : .357, 158, 0.650" long Zero JHP                      
Cartridge O.A.L. L6: 1.555 inch = 39.50 mm            
Barrel Length      : 4.2 inch = 106.7 mm            
                       
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested            
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand            
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet            
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.            
USE ONLY FOR COMPARISON !            
             
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time            
                                      %     Grains    Gramm   fps     %       psi     psi    ms            
---------------------------------  -----------------------------------------------------------------              
Accurate No.7                       68.9     11.5     0.74    1182    86.7    30625   10715   0.487  ! Near Maximum !
Alliant BLUE DOT                    89.2     11.2     0.73    1174    85.6    30625   10499   0.485  ! Near Maximum !
Accurate No.9                       77.0     12.6     0.82    1173    80.3    30625   10531   0.483  ! Near Maximum !  
Vihtavuori 3N37                     73.0      8.7     0.56    1139    99.6    30625    8672   0.486  ! Near Maximum !
Hodgdon Longshot                    56.6      8.8     0.57    1133    99.5    30625    8532   0.485  ! Near Maximum ! 
Vihtavuori N340                     71.0      7.3     0.47    1095   100.0    30625    7182   0.489  ! Near Maximum !

I wouldn't use QuickLOAD that way. QL is notorious for being very bad at estimating pressure with some powders. For example, if you plug in the numbers I gave above using the .672" long Hornady 158 XTP at 1.590 and A#9 14.9 grains (using default case volume), QL says the pressure is 53,303 psi. This is a long way from the Lyman MEASURED pressure of 42,900 CUP. The CUP max for 357 Mag is 45,000 CUP, and the psi max is 35,000 psi.

Using the QL estimate of 53,303 psi as your baseline goal, change the bullet parameters for length (.650) and OAL (1.555) for the Zero bullet. That estimates the pressure as 55,880 psi with 14.9 Gr A#9. QL estimates that by dropping the powder charge to 14.7 gives you a pressure of 53,470 psi, which is pretty close to the estimate it gave for the Hornady bullet. So, using the Zero bullet at 1.555" means you only have to reduce the charge of A#9 by 0.2 grains to get about the same pressure as using the Hornady XTP bullet.

 

[fxvr5]

With numbers from fxvr5, I ran a Quickload (QL) table with the powders from the OP.

Given the desire to use a specific bullet with no known actual test data, QL is probably as good as you are going to get for predicting performance and pressures. I used the default QL max recommended chamber pressure when I ran the table. This should be safe and going over it puts you more at risk of exceeding the SAAMI limit given that this is not actual test data. Starting below the values shown and working up is recommended.

QL does not account for cylinder gap, I typically subtract 50 fps from the prediction. The QL input for barrel length is muzzle to breech, so it includes the cylinder.

The very high muzzle pressures of AA7, AA9 and Blue Dot indicate that lots of flash/bang are expected. AA7 and Blue Dot give essentially the same performance as AA9 while using 10% less powder.

Actual measured data from Lyman #50 show the following max loads (velocity with 4.0" barrel Universal Receiver);

Blue Dot, 10.7 gr. 1158 fps, 39,800 CUP
A#7, 11.5 gr. 1220 fps, 38,700 CUP
A#9, 14.9 gr. 1357 fps, 42,900 CUP

The above data show that these 3 powders are not giving the same performance.

I've run the A#9 load in my S&W 4.0" gun and recorded a little over 1300 fps.

 

[AJC1]

With numbers from fxvr5, I ran a Quickload (QL) table with the powders from the OP.

Given the desire to use a specific bullet with no known actual test data, QL is probably as good as you are going to get for predicting performance and pressures. I used the default QL max recommended chamber pressure when I ran the table. This should be safe and going over it puts you more at risk of exceeding the SAAMI limit given that this is not actual test data. Starting below the values shown and working up is recommended.

QL does not account for cylinder gap, I typically subtract 50 fps from the prediction. The QL input for barrel length is muzzle to breech, so it includes the cylinder.

The very high muzzle pressures of AA7, AA9 and Blue Dot indicate that lots of flash/bang are expected. AA7 and Blue Dot give essentially the same performance as AA9 while using 10% less powder.

Cartridge          : .357 Magnum (SAAMI)              
Bullet             : .357, 158, 0.650" long Zero JHP                        
Cartridge O.A.L. L6: 1.555 inch = 39.50 mm              
Barrel Length      : 4.2 inch = 106.7 mm              
                         
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested              
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand              
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet              
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.              
USE ONLY FOR COMPARISON !              
               
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time              
                                      %     Grains    Gramm   fps     %       psi     psi    ms              
---------------------------------  -----------------------------------------------------------------                
Accurate No.7                       68.9     11.5     0.74    1182    86.7    30625   10715   0.487  ! Near Maximum !  
Alliant BLUE DOT                    89.2     11.2     0.73    1174    85.6    30625   10499   0.485  ! Near Maximum !  
Accurate No.9                       77.0     12.6     0.82    1173    80.3    30625   10531   0.483  ! Near Maximum !    
Vihtavuori 3N37                     73.0      8.7     0.56    1139    99.6    30625    8672   0.486  ! Near Maximum !  
Hodgdon Longshot                    56.6      8.8     0.57    1133    99.5    30625    8532   0.485  ! Near Maximum !   
Vihtavuori N340                     71.0      7.3     0.47    1095   100.0    30625    7182   0.489  ! Near Maximum !

Why are we reducing pmax to 30 from 35kpsi. We're already running the 35k handicap from the 40k cip and earlier American loads.... I don't load 40k much, but some powders don't even turn on 30k and below. Blue dot being one.

 

[AJC1]

Actual measured data from Lyman #50 show the following max loads (velocity with 4.0" barrel Universal Receiver);

Blue Dot, 10.7 gr. 1158 fps, 39,800 CUP
A#7, 11.5 gr. 1220 fps, 38,700 CUP
A#9, 14.9 gr. 1357 fps, 42,900 CUP

The above data show that these 3 powders are not giving the same performance.

I've run the A#9 load in my S&W 4.0" gun and recorded a little over 1300 fps.

I wonder what #7 would do at the same pressure as #9. 4.2k is a reduction of 10%

 

[.45Coltguy]

Whoo, this is like a dog chasing its own tail. Tantilizing thread here.

 

[BJung]

Wouldn't the powder with the lowest chamber pressure for any given velocity be the best choice for this snubby so there is less recoil?

 

[Walkalong]

Recoil is about burn speed (An excellent debate), projectile weight, powder weight, and velocity.

 

[BJung]

Recoil is about burn speed (An excellent debate), projectile weight, powder weight, and velocity.

I've been looking at the chamber pressure listed in my Lyman book and at times one particular powder will have a lower chamber pressure compared to other powder loads at a given range loads and mv. Shouldn't that powder with the lower chamber pressure have less recoil?

 

[fxvr5]

I've been looking at the chamber pressure listed in my Lyman book and at times one particular powder will have a lower chamber pressure compared to other powder loads at a given range loads and mv. Shouldn't that powder with the lower chamber pressure have less recoil?

No, not necessarily. It's not the chamber pressure that matters. It's the gas pressure at the muzzle that matters, and peak chamber pressure does not predict muzzle pressure very well.

The formula for recoil requires bullet speed, bullet weight and powder weight. There is no provision for peak chamber pressure. Slow burning powders generally require more powder weight and they will generally produce the most recoil when the same bullet is pushed to the same speed.

 

[GeoDudeFlorida]

Wouldn't the powder with the lowest chamber pressure for any given velocity be the best choice for this snubby so there is less recoil?

Keep in mind the OP’s goal is a big fireball and loud report. The best way to get those two things is incomplete burn in the chamber and high muzzle pressure. In my experience neither of those things add significant perceived recoil but I have had comments from other shooters that the higher flash does result in more recoil.

 

[P Flados]

I will admit that Quickload is not perfect. However, as previously noted AA9 published load data is "all over the map" (i.e. not perfect either).

And as far as using data with pressure in cup, that is my last resort. Hercules powder data allowed much higher charges based on the old cup style testing, and then found they need to back down when they went to the more accurate psi method. This was back in the early 1990s as I recall.

Again if there was real test data with a Zero 158 JHP bullet and the powders listed in the OP, recommendations would be easier. As it is, having the Quickload runs is going to provide about as good a comparison as you are going to get for this bullet loaded to this COAL with these specific powders.

As best I can tell, when Quickload is more than a tad bit different than published load data for magnum pistols, it tends to be on the conservative side most of the time (i.e. give results that indicate a lower max charge). However, I have seen some examples where using Quickload would allow higher charges than actual test data.

As far as pushing 357 mag to max pressure, I have to ask why. When you have actual test data for the specific bullet in question, the risk is low. When you are using test data from one bullet to estimate performance for a different bullet are you really confident that your bullet will not increase pressure. Again look at published data for the 357 mag and you can find all kinds of unexpected variations for what look to be very similar loads.

And stopping short of recommending absolute max is something of a "standard practice" for me for this type of application. If there was a stated need to push for absolute max performance, using a "generic" bullet is probably a poor choice. I would recommend finding a specific bullet that is an exact match to data with results in psi from a couple of sources and duplicating one of the published loads as close as possible.

In truth, the OP stated the intention to fire these loads in a GP-100. For that specific gun, there is probably less need for my caution. However, anything I recommend can be used by anybody reading this thread and they may have a much less heavy duty gun. Remember what we are doing here guys. For probably better than 95% of the time, reloads are used to support shooting as a hobby. If I want a more powerful round than a 30,000 psi 357 magnum, my first choice is simply to use more gun. Pushing loads out to where you increase the risk of gun damage (or worse) just does not make sense to me when we are talking about the normal use of reloads.

 

[Shak3s1977]

I'd suggest trying A#9 before buying another powder. I get faster velocity with #9 than with 2400 from a 4" barrel and 158 grain bullets. Bottom line, A#9 might be all you need. No need to spend more money if you don't need to.

I would also try the #9 first since you already have some. It meters well, downloads well, and burns pretty clean.

 

[Shak3s1977]

Of the powders you have, AA#9 is a great 357 Magnum powder.

Due to sticky extraction, I stopped at 12.0 grains with a 158 L bullet

I also load 12.0gr of AA#9 with 158gr lead bullets. Have gone up to 13.5gr with #9 and 158gr bullets, but 95% are loaded to 12.0grs. It's a nice accurate load.

These are shot out of my wife's GP100

 

[fxvr5]

Pushing loads out to where you increase the risk of gun damage (or worse) . . .

If loading a cartridge near its max SAAMI pressure limit risks gun damage or worse, we're in trouble. By the way, what is your "worse"?

 

[AJC1]

I will admit that Quickload is not perfect. However, as previously noted AA9 published load data is "all over the map" (i.e. not perfect either).

And as far as using data with pressure in cup, that is my last resort. Hercules powder data allowed much higher charges based on the old cup style testing, and then found they need to back down when they went to the more accurate psi method. This was back in the early 1990s as I recall.

Again if there was real test data with a Zero 158 JHP bullet and the powders listed in the OP, recommendations would be easier. As it is, having the Quickload runs is going to provide about as good a comparison as you are going to get for this bullet loaded to this COAL with these specific powders.

As best I can tell, when Quickload is more than a tad bit different than published load data for magnum pistols, it tends to be on the conservative side most of the time (i.e. give results that indicate a lower max charge). However, I have seen some examples where using Quickload would allow higher charges than actual test data.

As far as pushing 357 mag to max pressure, I have to ask why. When you have actual test data for the specific bullet in question, the risk is low. When you are using test data from one bullet to estimate performance for a different bullet are you really confident that your bullet will not increase pressure. Again look at published data for the 357 mag and you can find all kinds of unexpected variations for what look to be very similar loads.

And stopping short of recommending absolute max is something of a "standard practice" for me for this type of application. If there was a stated need to push for absolute max performance, using a "generic" bullet is probably a poor choice. I would recommend finding a specific bullet that is an exact match to data with results in psi from a couple of sources and duplicating one of the published loads as close as possible.

In truth, the OP stated the intention to fire these loads in a GP-100. For that specific gun, there is probably less need for my caution. However, anything I recommend can be used by anybody reading this thread and they may have a much less heavy duty gun. Remember what we are doing here guys. For probably better than 95% of the time, reloads are used to support shooting as a hobby. If I want a more powerful round than a 30,000 psi 357 magnum, my first choice is simply to use more gun. Pushing loads out to where you increase the risk of gun damage (or worse) just does not make sense to me when we are talking about the normal use of reloads.

All sounding very reasonable, I guess we're considering different things. What I'm looking for is powder performance and efficacy, while most are chasing velosity. Powders like blue dot, 4227, and #9 all of which I use give their best combustion numbers in that 30-35kpsi range. So for me it's not about more, but about the powder being in its happy place. I've seen a decrease in required pressure with heavier for caliber bullets which would take me a lifetime to map out with #9. A 180 seems to have a happy spot near 20k which is a huge shift for that powder.
My process is to run a ladder looking for good burn, the next trip load a ladder in the good burn area and look for accuracy. In pistols or carbines velosity is not one of my factors unless it's a special load for hunting using a bullet with terminal requirements for proper operation. That would not be the case with a zero bullet.

I do very much like to see your data runs and think it adds real value to the posts....

 

[alank2]

I also load 12.0gr of AA#9 with 158gr lead bullets. Have gone up to 13.5gr with #9 and 158gr bullets, but 95% are loaded to 12.0grs. It's a nice accurate load.

These are shot out of my wife's GP100

What kind of velocities are you getting; that is pretty much the same 2.5" GP100 I'll be working a load up in.

 

[Shak3s1977]

What kind of velocities are you getting; that is pretty much the same 2.5" GP100 I'll be working a load up in.

I don't know if I have load data for the 12.0gr loads. I'll have to look in my notes when I get home.

I do know with almost every load I've made and shot in a 6in GP100 and the 2.5inch GP100, the 2.5inch is roughly 100-150fps slower than the 6inch gun according to our chronograph. That was using True Blue, 2400, AA9, AA7 and Unique.