257 weatherby mag quickload 120gr swift a-frame

tyson22250

Beginner
Nov 8, 2010
83
0
Hell just wondering if someone could please do a quickload for my 257 weatherby mag load
Rifle is a weatherby accumark 26”
Bullets-120gr swift a-frame
Cases-Norma/weatherby 257
Primers-Fed 215 mag
Powders imr 7828, Retumbo h1000 imr 4350

Thanks in advance
 

DrMike

Ballistician
Nov 8, 2006
35,188
1,737
Code:
Cartridge          : .257 Weath. Mag
Bullet             : .257, 120, Swift A-Frame SS
Useable Case Capaci: 77.053 grain H2O = 5.003 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : Hodgdon Retumbo

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   88    63.00   3033    2451   47603  12843    100.0    1.298
-09.0   89    63.70   3062    2499   48922  12919    100.0    1.285
-08.0   90    64.40   3092    2547   50286  12994    100.0    1.273
-07.0   91    65.10   3121    2595   51697  13068    100.0    1.260
-06.0   92    65.80   3150    2644   53155  13141    100.0    1.248
-05.0   93    66.50   3179    2693   54666  13213    100.0    1.236  ! Near Maximum !
-04.0   94    67.20   3208    2742   56229  13284    100.0    1.224  ! Near Maximum !
-03.0   95    67.90   3236    2791   57843  13354    100.0    1.212  ! Near Maximum !
-02.0   96    68.60   3265    2840   59521  13423    100.0    1.200  ! Near Maximum !
-01.0   97    69.30   3293    2890   61253  13492    100.0    1.188  ! Near Maximum !
+00.0   98    70.00   3322    2940   63050  13559    100.0    1.176  ! Near Maximum !
+01.0   99    70.70   3350    2990   64910  13624    100.0    1.164  !DANGEROUS LOAD-DO NOT USE!
+02.0  100    71.40   3378    3040   66838  13689    100.0    1.153  !DANGEROUS LOAD-DO NOT USE!
+03.0  101    72.10   3406    3091   68835  13753    100.0    1.141  !DANGEROUS LOAD-DO NOT USE!
+04.0  102    72.80   3434    3142   70904  13816    100.0    1.129  !DANGEROUS LOAD-DO NOT USE!
+05.0  103    73.50   3462    3194   73036  13877    100.0    1.118  !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     98    70.00   3439    3152   75824  13128    100.0    1.114  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba     98    70.00   3142    2631   51435  14078     99.4    1.252

Code:
Cartridge          : .257 Weath. Mag
Bullet             : .257, 120, Swift A-Frame SS
Useable Case Capaci: 77.053 grain H2O = 5.003 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : IMR 7828

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   82    56.70   2995    2391   48902  12644     98.3    1.292
-09.0   83    57.33   3024    2437   50180  12764     98.6    1.279
-08.0   84    57.96   3053    2484   51490  12881     98.8    1.267
-07.0   85    58.59   3082    2531   52833  12993     99.0    1.255
-06.0   86    59.22   3111    2578   54208  13101     99.2    1.243
-05.0   87    59.85   3139    2626   55619  13205     99.4    1.231  ! Near Maximum !
-04.0   88    60.48   3168    2674   57064  13304     99.5    1.219  ! Near Maximum !
-03.0   89    61.11   3197    2723   58546  13398     99.7    1.208  ! Near Maximum !
-02.0   89    61.74   3225    2772   60066  13488     99.8    1.196  ! Near Maximum !
-01.0   90    62.37   3254    2821   61624  13572     99.9    1.185  ! Near Maximum !
+00.0   91    63.00   3282    2870   63223  13651     99.9    1.173  ! Near Maximum !
+01.0   92    63.63   3310    2920   64870  13725    100.0    1.162  !DANGEROUS LOAD-DO NOT USE!
+02.0   93    64.26   3338    2970   66567  13794    100.0    1.151  !DANGEROUS LOAD-DO NOT USE!
+03.0   94    64.89   3367    3020   68314  13858    100.0    1.140  !DANGEROUS LOAD-DO NOT USE!
+04.0   95    65.52   3395    3070   70114  13920    100.0    1.129  !DANGEROUS LOAD-DO NOT USE!
+05.0   96    66.15   3422    3121   71968  13981    100.0    1.118  !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     91    63.00   3405    3089   73262  13190    100.0    1.116  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba     91    63.00   3108    2574   52864  13646     96.7    1.245

Code:
Cartridge          : .257 Weath. Mag
Bullet             : .257, 120, Swift A-Frame SS
Useable Case Capaci: 77.053 grain H2O = 5.003 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : IMR 4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   75    52.65   2922    2274   49717  11209     99.7    1.279
-09.0   75    53.24   2947    2314   50886  11296     99.8    1.268
-08.0   76    53.82   2973    2355   52083  11381     99.9    1.257
-07.0   77    54.41   2998    2395   53308  11462     99.9    1.247
-06.0   78    54.99   3023    2435   54562  11539    100.0    1.236  ! Near Maximum !
-05.0   79    55.58   3048    2476   55846  11613    100.0    1.225  ! Near Maximum !
-04.0   79    56.16   3073    2516   57160  11684    100.0    1.215  ! Near Maximum !
-03.0   80    56.75   3098    2557   58505  11754    100.0    1.204  ! Near Maximum !
-02.0   81    57.33   3123    2598   59881  11824    100.0    1.194  ! Near Maximum !
-01.0   82    57.92   3147    2639   61290  11893    100.0    1.184  ! Near Maximum !
+00.0   83    58.50   3171    2680   62733  11961    100.0    1.173  ! Near Maximum !
+01.0   84    59.09   3196    2721   64209  12029    100.0    1.163  !DANGEROUS LOAD-DO NOT USE!
+02.0   84    59.67   3220    2762   65720  12097    100.0    1.153  !DANGEROUS LOAD-DO NOT USE!
+03.0   85    60.26   3243    2803   67266  12163    100.0    1.143  !DANGEROUS LOAD-DO NOT USE!
+04.0   86    60.84   3267    2844   68849  12230    100.0    1.134  !DANGEROUS LOAD-DO NOT USE!
+05.0   87    61.43   3291    2886   70470  12295    100.0    1.124  !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     83    58.50   3257    2827   70514  11656    100.0    1.126  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba     83    58.50   3045    2470   54883  12219     99.0    1.252  ! Near Maximum !
 

Orezona

Beginner
Jan 23, 2020
23
2
What is B_Time ms ?

I'm new to reading the quick load data. Thank you in advance.
 

tyson22250

Beginner
Nov 8, 2010
83
0
Thanks dr mike
I stumbled across this one last night. Wonder why it’s a little different everything being equal?
 

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DrMike

Ballistician
Nov 8, 2006
35,188
1,737
tyson22250":2589no53 said:
Thanks dr mike
I stumbled across this one last night. Wonder why it’s a little different everything being equal?

Difference in barrel length. This was older data calculated with differing test data provided by manufacturers. The difference appears to be minimal.
 

SJB358

Ballistician
Dec 24, 2006
31,355
654
We used the 120 Partition with RL25 and RL33 and man, they work like a champ. That's a seriously flat shooting load that carries the mail real well for the 257. The A-Frame's should be giant killers.
 

tyson22250

Beginner
Nov 8, 2010
83
0
SJB358
That’s good to know I’ve used the 110gr AccuBond with great results but I got drawn for elk along with brother and dad. I’m gunna get ridiculed for using a .257 id imagine but I’ve seen what it does to mule deer vs my 7mm rem mag and there’s not a lot of difference. I wanted one of the toughest bullets to put my mind a little at ease. What kind of velocity were you getting with rl25 and 33?
 

SJB358

Ballistician
Dec 24, 2006
31,355
654
I’d have no issues with a 120 Partition or Swift on any elk. We got 3250 with 25 and 3350 with 33 in my brothers 24” Vanguard. They both shot incredible as well.
 

Divernhunter

Handloader
Apr 1, 2009
720
48
71.5grs RL25 and Fed 215 primer with the 120gr Swift A-Frame works best for me. Tried H-1000, Retumbo and IMR 7828SSC and the RL25 preformed better for me
 
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