257 weatherby mag quickload 120gr swift a-frame

[tyson22250]

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]

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

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

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]

What is B_Time ms ?

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

 

[mjcmichigan]

Propellant burn time


Sent from my iPad using Tapatalk

 

[tyson22250]

Thanks dr mike
I stumbled across this one last night. Wonder why it’s a little different everything being equal?

 

[DrMike]

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.

 

[Orezona]

Propellant burn time


Sent from my iPad using Tapatalk

Thank you sir.

 

[SJB358]

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]

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]

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.

 

[tyson22250]

Thanks !

 

[Divernhunter]

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