280 ai speed

[ramrod79]

I use 60gr and 60.5 for the 140s toss up on the accuracy and 55.5 for the 160s seated at 3.330 is my ticket .

 

[ramrod79]

Target is turned sideways but that's the 140 load

 

[Ridgerunner665]

I finally got some shooting done with my 280 Ackley (24" barrel), thought I'd revisit this...below is actual chrono data, followed by a dialed in QuickLoad rundown (matched to my rifle)

150 ABLR, Norma MRP

60.5 = 3,043 fps
61 = 3,070
61.5 = 3,093 fps
62 = 3,120 fps
62.5 = 3,137 fps (too hot, do not use)
63 = 3,167 fps (too hot, do not use)
63.5 = 3,192 fps (way too hot, ejector mark, do not use)

Cartridge          : .280 Ack Imp
Bullet             : .284, 150, Nosler Accubond LR 58734 G7
Useable Case Capaci: 65.441 grain H2O = 4.249 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Norma MRP ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.807% 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

-08.1   91    57.00   2877    2758   48705  11742     99.6    1.277
-07.3   91    57.50   2902    2806   50071  11808     99.7    1.261
-06.5   92    58.00   2927    2854   51474  11870     99.8    1.245
-05.6   93    58.50   2952    2902   52916  11928     99.9    1.230
-04.8   94    59.00   2976    2951   54397  11981    100.0    1.214
-04.0   95    59.50   3001    2999   55920  12030    100.0    1.199  ! Near Maximum !
-03.2   95    60.00   3025    3048   57486  12075    100.0    1.184  ! Near Maximum !
-02.4   96    60.50   3049    3097   59095  12117    100.0    1.170  ! Near Maximum !
-01.6   97    61.00   3074    3147   60750  12159    100.0    1.155  ! Near Maximum !
-00.8   98    61.50   3098    3196   62452  12200    100.0    1.141  ! Near Maximum !
+00.0   98    62.00   3122    3246   64202  12240    100.0    1.127  ! Near Maximum !
+00.8   99    62.50   3146    3296   66003  12280    100.0    1.113  !DANGEROUS LOAD-DO NOT USE!
+01.6  100    63.00   3169    3346   67855  12319    100.0    1.100  !DANGEROUS LOAD-DO NOT USE!
+02.4  101    63.50   3193    3396   69760  12358    100.0    1.086  !DANGEROUS LOAD-DO NOT USE!
+03.2  102    64.00   3217    3446   71722  12395    100.0    1.073  !DANGEROUS LOAD-DO NOT USE!
+04.0  102    64.50   3240    3497   73741  12433    100.0    1.060  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     98    62.00   3187    3383   71171  11987    100.0    1.081  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     98    62.00   3040    3079   57314  12509     99.8    1.181  ! Near Maximum !

First try at a group with the 150 ABLR's (62 grains of MRP)...shows promise I think.


Also...

160 Accubond, Norma MRP

58.5 = 2,956 fps
59 = 2,972 fps
59.5 = 2,989 fps
60 = 3,003 fps, no signs of pressure but a dialed in QuickLoad says 60.5 is maxed out at 3,027 fps, so I'm not chasing this one any further.

 

[varmintH8R]

Great info, thanks for staying with it and putting it up for us.