AA5744 and 7.62x39

[Tommy Gun]

Back when the covid started I purchased some 5744 because 1680 was OOS. Before I could really start messing with it was able to purchase #8 of 1680 and just stuck with my regular recipie. Well now I have a couple hundred prepped cases and want to use it up.

Not sure if the load data for 5744 in the Accurate web pages was calculated for bolt guns (annoying they do not have AR/AK or semi auto recipies readily available for any of the major brands) Max load for 5744 is 23.8 at 2400 FPS, and was thinking of starting around 22.5 and working up as I want velocity around 2200 and do not know how off it would be for semi auto.

Anyone here use this powder for gas guns and offer any insights?

[Tommy Gun]

Damnit sorry, will be using 123gr PAVI FMJ's (only brand I could find all throughout covid), and will be firing them out of a 16" AR Upper.

[ar15barrels]

Here is what Quickload thinks.
This is NOT laboratory tested load data, but it should give you an idea where to start working up a load:

Cartridge          : 7.62 x 39 (M43) Russ.
Bullet             : .310, 123, PrviPartizan FMJ B-074
Useable Case Capaci: 30.232 grain H2O = 1.963 cm³
Cartridge O.A.L. L6: 2.190 inch = 55.63 mm
Barrel Length      : 16.0 inch = 406.4 mm
Powder             : Accurate 5744

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.87% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-08.7   79    21.00   2151    1264   37181   5765     93.3    0.995
-07.8   80    21.20   2169    1285   38070   5825     93.7    0.984
-07.0   80    21.40   2187    1306   38978   5884     94.0    0.974
-06.1   81    21.60   2205    1328   39905   5942     94.3    0.963
-05.2   82    21.80   2223    1350   40851   6000     94.7    0.953
-04.3   83    22.00   2241    1372   41816   6056     95.0    0.942
-03.5   83    22.20   2259    1394   42802   6112     95.3    0.932
-02.6   84    22.40   2277    1416   43808   6167     95.6    0.922  ! Near Maximum !
-01.7   85    22.60   2295    1438   44836   6222     95.8    0.913  ! Near Maximum !
-00.9   86    22.80   2312    1460   45885   6275     96.1    0.903  ! Near Maximum !
+00.0   86    23.00   2330    1483   46956   6328     96.4    0.894  ! Near Maximum !
+00.9   87    23.20   2348    1505   48050   6380     96.6    0.885  ! Near Maximum !
+01.7   88    23.40   2365    1528   49168   6430     96.9    0.876  ! Near Maximum !
+02.6   89    23.60   2383    1551   50308   6480     97.1    0.867  ! Near Maximum !
+03.5   89    23.80   2401    1574   51474   6529     97.3    0.858  !DANGEROUS LOAD-DO NOT USE!
+04.3   90    24.00   2418    1597   52664   6577     97.6    0.849  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 3% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 3% relative to nominal value:
+Ba     86    23.00   2362    1523   49017   6361     97.6    0.877  ! Near Maximum !
Data for burning rate decreased by 3% relative to nominal value:
-Ba     86    23.00   2296    1440   44907   6275     94.9    0.912  ! Near Maximum !

It does seem to track with the published numbers you mentioned in the first post though.

[Tommy Gun]

Thanks Randall. Looks like 22.5 will be where I wanna start, going a little above and over.

[Tommy Gun]

So strange results. Loaded 22, 22.5 and 23 and velocity was 2014, 2064, 2105 respectively. No pressure signs (didn't expect any) and loads seemed to group well but now do I start loading closer to max. Judging by my results 24gr would get me the velocity I'm looking for but judging by all data it would put me at super max.

Not sure if seating depth and crimp might be causing such a huge disparity between actual vs. projected velocities. So looks like I'll inch close to 23.5 and call it a day. While 2200ish velocity is my sweet spot it is so off what should be I must be missing something.

[ar15barrels]

So strange results. Loaded 22, 22.5 and 23 and velocity was 2014, 2064, 2105 respectively. No pressure signs (didn't expect any) and loads seemed to group well but now do I start loading closer to max. Judging by my results 24gr would get me the velocity I'm looking for but judging by all data it would put me at super max.

Not sure if seating depth and crimp might be causing such a huge disparity between actual vs. projected velocities. So looks like I'll inch close to 23.5 and call it a day. While 2200ish velocity is my sweet spot it is so off what should be I must be missing something.

Your chamber could be larger than nominal or the throat longer than nominal.
This will lower pressure and velocity.

If your barrel length is correct, you can ignore the powder charge and use the velocity on the Quickload simulation above to show you where you should be on pressure as well as roughly how much more powder you need to get to your desired velocity.

If your load comes in 100fps slow, move down the simulation to find the velocity you want.
Then count the lines you had to move.
Let's say it was 7 lines.
0.2gr per line gets you 1.4gr more powder.

It's not exact, but it will get you an idea what you need to do.

[kcheung2]

The test barrel in the data was 21", you're using a 16", so it makes sense that your velocity is slower.

[Tommy Gun]

No the test load data is for 16inch barrel. I'm using Randalls info in post 3

[Sandspider500]

Hmm, run that same load with a 20" barrel.

[kcheung2]

No the test load data is for 16inch barrel. I'm using Randalls info in post 3