How To Determine Subsonic Loads?

[Greekboi95]

Hi guys, I do not cast myself but shoot powder coated bullets in a few different calibers and am fortunate to have access to purchase most bullet weights and sizes I would like to shoot.

Recently having an itch to try load heavy bullets (195gr) sub sonic in 7.62 x 39, I haven't been able to find a "reliable" way to determine a starting load for it which got me thinking, how does one extrapolate load data for a specific cartridge using pistol powder specifically?

I understand that to low of a charge may incur squib loads or to much space in the cartridge causes other issues etc.

I read that for a "safe" starting load, you should take your standard supersonic load and work out 15% - 20% of said load to determine a starting point. Does this sound correct? And if so, how would you know what pistol powder to use then? Fast, medium or slow burning?

I have access to the following pistol powders:

Hodgdon Tite Group
Lovex D032, D036, D037.1
Vectan BA 9.5
Somchem MP200

Your feedback would be greatly appreciated!

GB95

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[Grayone]

11 grain IMR4227 and go down to the level you like.

[P Flados]

For "less loud" loading, typically people try for a velocity of around 1000 fps.

Noise is also reduced by going with the fastest powder that will give you your desired velocity without exceeding the allowed chamber pressure. With a faster powder, the chamber pressure will be high, but the pressure will drop of more quickly and actually gives you a lower pressure as the bullet leaves the muzzle.

For what you are doing now, the normal starting point rules are no longer applicable.

Quickload does not have all of your powders. Of the ones it does have, this should give you an estimate of what it will take for subs with a 195 gr cast bullet. Velocities below are approximates and are affected by a number of parameters. If you get a sonic crack, back off a little. If it is quiet, you can work up a little until you hear the crack.

Cartridge          : 7.62 x 39 (M43) Russ.
Bullet             : .312, 195
Seating Depth      : .409 inch
Cartridge O.A.L. L6: 2.190 inch = 55.63 mm
Barrel Length      : 16.3 inch = 414.0 mm


These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
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
---------------------------------  -----------------------------------------------------------------
Hodgdon TiteGroup                   26.3      5.5     0.35    1000   100.0    19930    1317   1.874
Lovex D032                          24.2      5.2     0.33    1000   100.0    17103    1372   1.950
Lovex D036                          22.0      5.8     0.37    1000   100.0    11901    1653   2.178
Somchem MP200                       29.7      5.6     0.36    1000   100.0    14449    1464   2.065

[Milky Duck]

with 7.62x39mm and a 151 grn cast subsonic happens about 4-5-6 grns of trailboss UNLESS you use magnum primer,which then makes its down below 4 grns...and let me tell you my friends thats getting scary small amount to put in case.
with a suppressor its easy as you slowly lower charge weight till the noise drops off.... great fun plinking but not my cuppa tea on game,just zero shock power.

[Greekboi95]

For "less loud" loading, typically people try for a velocity of around 1000 fps.

Noise is also reduced by going with the fastest powder that will give you your desired velocity without exceeding the allowed chamber pressure. With a faster powder, the chamber pressure will be high, but the pressure will drop of more quickly and actually gives you a lower pressure as the bullet leaves the muzzle.

For what you are doing now, the normal starting point rules are no longer applicable.

Quickload does not have all of your powders. Of the ones it does have, this should give you an estimate of what it will take for subs with a 195 gr cast bullet. Velocities below are approximates and are affected by a number of parameters. If you get a sonic crack, back off a little. If it is quiet, you can work up a little until you hear the crack.

Cartridge          : 7.62 x 39 (M43) Russ.
Bullet             : .312, 195
Seating Depth      : .409 inch
Cartridge O.A.L. L6: 2.190 inch = 55.63 mm
Barrel Length      : 16.3 inch = 414.0 mm


These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
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
---------------------------------  -----------------------------------------------------------------
Hodgdon TiteGroup                   26.3      5.5     0.35    1000   100.0    19930    1317   1.874
Lovex D032                          24.2      5.2     0.33    1000   100.0    17103    1372   1.950
Lovex D036                          22.0      5.8     0.37    1000   100.0    11901    1653   2.178
Somchem MP200                       29.7      5.6     0.36    1000   100.0    14449    1464   2.065

Thank you for your response sir, it is greatly appreciated.

Do you recommend a dacron or similar filler for any of these approximate loads?



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[Greekboi95]

with 7.62x39mm and a 151 grn cast subsonic happens about 4-5-6 grns of trailboss UNLESS you use magnum primer,which then makes its down below 4 grns...and let me tell you my friends thats getting scary small amount to put in case.
with a suppressor its easy as you slowly lower charge weight till the noise drops off.... great fun plinking but not my cuppa tea on game,just zero shock power.

The issue is that we dont get Trailboss in South Africa nor do we have any type of similar powder thats been developed to take up that much case capacity.

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[P Flados]

I have tried fillers and did not like using them.

With a low percent fill and fast burning powders, you can get more velocity (better ignition) with the powder to the rear (tilt muzzle up prior to discharge), but even with powder forward you get reliable ignition. I use this type of load a lot. For single action handgun shooting, I have a routine of going muzzle upward as I cock the gun and then lower the gun to point of aim.

While developing sub loads, I would do similar. In actual shooting, even without the "tip up first" the velocity variations typically cause less vertical spread than you would expect as closer ranges. On the other hand, if you are shooting at extended distances, the "tip up first" is probably needed.

[P Flados]

FYI, I have recently been participating in a thread on another forum discussing good metering fast burning powders with lower densities. I did some "homework" on the subject and some others chipped in some info. I learned a few things.

For this topic, good metering is less important.

Here are some of the less dense powders (bigger VMD numbers as listed below) listed with faster on top (this came from www.tacticoolproducts.com).

I would bet that the really big VMD number is part of why Red Dot has worked so well for reduced power rifle loads (search for "Ed Harris The Load").

Vihta Vuori N310        .1214 
Hodgdon Titewad         .1300 
Accurate Nitro 100      .1349 
Accurate Solo 1000      .1331 
Alliant Red Dot         .1413 
Alliant American Select .1341 
Winchester AA Plus      .1296 
Hodgdon Clays           .1462 
Vihta Vuori N320        .1210 
Ramshot Competition     .1278
Winchester WST          .1205

[Driver man]

I shoot 170g 195gand currently 208g in 7.62x39.I use AP50 powder. I use 5grains,6grains and 7 grains with the boolit seated as long as the magazine permits. The 1:9.75 twist stabilises well. Ihave a Norinco bolt gun cut down to 16inch barrel with a moderator. Silent and deadly on goats etc at 100 yds