[deadon]

I'm starting to load for my AR, I noticed an article on the internet about being aware of the difference between loading for a bolt action and a AR.
The article said that due to the mech action of the bolt lugs that you should not load as heavy for an AR. I'm wanting to load a 55gr/3200fps bullet, using AA 2230 powder, I'm using a Lee load manual to go by. This load is a little below the do-not-exceed load for this weight bullet. Does anyone know if this would be OK considering what the article stated? This article referred to a load chart put out for ARs by Sierra.

 

[steve4102]

The AR-15 5.56 will handle pressures in the 62K range as it was designed for. If your AR is a true 223 then it should get a diet of 55K psi max.

Most all load data is 223 data which has a Max Average Pressure (MAP) of 55K psi. There is true 5.56 data with a MAP of 62K psi available from Western Powders found here.

http://www.ramshot.com/wp-content/uploads/2010/09/ramshot_handgun_rifle.pdf

http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf

I'm wanting to load a 55gr/3200fps bullet, using AA 2230 powder, I'm using a Lee load manual to go by.

Lee does not develop and test their own load data. They copy if from other sources, mainly the powder manufacturers pressure tested data.

AA2230 has changed recently and the Lee manual may not be accurate any longer. Go to the Accurate Powder link above and get the new updated version for 2230.

3200fps is right up there towards the Max with the 55gr bullets and a 24 inch barrel. If your AR is a Carbine with a 16 inch barrel max velocity will be 9% less, more like 2900fps. If your AR has a 20 inch barrel expect a Max velocity of 3050-3100fps.

Remember load data is NOT a recipe and you should never assume that a published Max charge will be safe in your rifle. Always, start low and work up.

 

[steve4102]

I think you my be pushing it with 3200fps in your 18 inch barrel. Proceed with caution.

Here is Quickload data for 55gr Nosler BT and 2230 with 24 inch barrel. Note it is spot on with Accurate Powders data. Accurate list 24.5gr as Max in the 223.

 Cartridge          : 5.56 mm NATO - 5.56 x 45 mm
Bullet             : .224, 55, Nosler BalTip 39526
Cartridge O.A.L. L6: 2.260 inch or 57.40 mm
Barrel Length      : 24.0 inch or 609.6 mm
Powder             : Accurate 2230 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0   75    19.60   2608     831   28071   5395     89.6    1.331
-18.0   77    20.09   2672     872   29994   5553     90.8    1.296
-16.0   79    20.58   2736     914   32054   5705     92.0    1.262
-14.0   81    21.07   2799     957   34259   5850     93.1    1.229
-12.0   82    21.56   2862    1000   36621   5988     94.2    1.196
-10.0   84    22.05   2925    1045   39152   6118     95.1    1.162
-08.0   86    22.54   2988    1090   41863   6239     96.0    1.127
-06.0   88    23.03   3051    1137   44771   6352     96.8    1.094
-04.0   90    23.52   3113    1184   47891   6455     97.5    1.062
-02.0   92    24.01   3175    1231   51241   6548     98.1    1.032
[B][B]+00.0   94    24.50   3237    1280   54841   6631     98.7    1.002  ! Near Maximum ![/B][/B]
+02.0   96    24.99   3298    1329   58714   6703     99.1    0.974  ! Near Maximum !
+04.0   97    25.48   3359    1378   62887   6763     99.5    0.946  !DANGEROUS LOAD-DO NOT USE!
+06.0   99    25.97   3420    1428   67387   6811     99.7    0.920  !DANGEROUS LOAD-DO NOT USE!
+08.0  101    26.46   3480    1479   72248   6846     99.9    0.894  !DANGEROUS LOAD-DO NOT USE!
+10.0  103    26.95   3540    1530   77508   6869    100.0    0.869  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba     94    24.50   3378    1394   65824   6418    100.0    0.930  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba     94    24.50   3042    1130   44269   6516     93.2    1.098

 

[steve4102]

Same data adjusted for your 18 inch barrel. Note the High Pressure to achieve your desired 3200fps.

 Cartridge          : 5.56 mm NATO - 5.56 x 45 mm
Bullet             : .224, 55, Nosler BalTip 39526
Cartridge O.A.L. L6: 2.260 inch or 57.40 mm
Barrel Length      : 18.0 inch or 457.2 mm
Powder             : Accurate 2230 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0   75    19.60   2415     712   28071   7246     85.8    1.133
-18.0   77    20.09   2477     749   29994   7487     87.3    1.103
-16.0   79    20.58   2539     788   32054   7723     88.6    1.073
-14.0   81    21.07   2602     827   34259   7951     89.9    1.044
-12.0   82    21.56   2664     867   36621   8172     91.2    1.016
-10.0   84    22.05   2727     908   39152   8385     92.3    0.985
-08.0   86    22.54   2789     950   41863   8588     93.4    0.954
-06.0   88    23.03   2852     993   44771   8781     94.4    0.925
-04.0   90    23.52   2915    1038   47891   8962     95.4    0.897
-02.0   92    24.01   2977    1083   51241   9132     96.2    0.869
+00.0   94    24.50   3040    1129   54841   9288     97.0    0.843  ! Near Maximum !
+02.0   96    24.99   3102    1175   58714   9430     97.7    0.818  ! Near Maximum !
+04.0   97    25.48   3165    1223   62887   9557     98.3    0.793  !DANGEROUS LOAD-DO NOT USE!
[B]+06.0   99    25.97   3227    1272   67387   9668     98.8    0.769  !DANGEROUS LOAD-DO NOT USE![/B]
+08.0  101    26.46   3289    1321   72248   9763     99.2    0.747  !DANGEROUS LOAD-DO NOT USE!
+10.0  103    26.95   3351    1371   77508   9840     99.6    0.724  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba     94    24.50   3193    1245   65824   9211     99.9    0.778  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba     94    24.50   2839     984   44269   8911     90.2    0.928

 

[deadon]

What about another powder and still keep the wt and fps?
Or would I have to change bullet wt but keep the fps?

 

[JTofGPD]

I use midsouth nightmare extreme or hornady 55 gr spsx with 24 gr TAC. I do not have a chrony, but the hornady books put max charge of TAC at 24.7 gr around 3200 fps and 23.9 at 3100 fps. Can't beat the price of midsouth bullets- $54/500 shipped. I get sub moa at 100 yards with iron sights.

My Speer manual lists AA2230 loaded with a 55 gr tnt or hp boolit at 24 gr minimum and 26 grains at 3233 fps.

 

[deadon]

I'm trying to stay around 54000psi and keep the 55gr bullet at around 3200fps. Could you say if a load chart said a do not exceed load was 55000 psi at 3300 fps, would it be safe to say that any load under that amount of powder down to the starting amount would be OK? In order to get around 3200fps. I have looked at a few load charts and it seems to be difficult to find a 55gr bullet that is 3200fps or less to have less than 54000 psi.

 

[steve4102]

Most load data for the 223/5.56 is with a 24 inch barrel. No matter how you slice it your 18 inch barrel will net you a velocity loss of about 200fps.

I think you should pick a bullet/powder combo, do your load work up starting low, shoot over a Chrony, then test out your optics and see how they compare to the paper manual.

 

[deadon]

Steve

This is the information I will use.


Thanks

Steve B