257 Weatherby

[boomer68]

Wow, that is impressive! Now I really have to try some


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[Dwh7271]

MRP and the Swift

Cartridge : .257 Weath. Mag
Bullet : .257, 100, Swift Scirocco
Useable Case Capaci: 77.556 grain H2O = 5.036 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 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 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 80 59.69 2999 1997 38278 13706 95.4 1.378
-18.0 82 61.18 3076 2101 41152 14084 96.5 1.338
-16.0 84 62.67 3154 2208 44201 14433 97.5 1.292
-14.0 86 64.16 3231 2318 47460 14751 98.3 1.249
-12.0 88 65.66 3308 2429 50945 15035 99.0 1.208
-10.0 90 67.15 3384 2542 54683 15285 99.5 1.168 ! Near Maximum !
-08.0 92 68.64 3459 2657 58680 15496 99.8 1.130 ! Near Maximum !
-06.0 94 70.13 3534 2773 62963 15667 100.0 1.094 ! Near Maximum !
-04.0 96 71.63 3608 2891 67552 15803 100.0 1.059 !DANGEROUS LOAD-DO NOT USE!
-02.0 98 73.12 3681 3009 72475 15928 100.0 1.025 !DANGEROUS LOAD-DO NOT USE!
+00.0 100 74.61 3753 3128 77758 16049 100.0 0.993 !DANGEROUS LOAD-DO NOT USE!
+02.0 102 76.10 3825 3248 83434 16165 100.0 0.962 !DANGEROUS LOAD-DO NOT USE!
+04.0 104 77.59 3896 3370 89539 16275 100.0 0.932 !DANGEROUS LOAD-DO NOT USE!
+06.0 106 79.09 3966 3492 96114 16379 100.0 0.903 !DANGEROUS LOAD-DO NOT USE!
+08.0 108 80.58 4036 3617 103204 16477 100.0 0.875 !DANGEROUS LOAD-DO NOT USE!
+10.0 110 82.07 4105 3743 110862 16568 100.0 0.848 !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 100 74.61 3828 3254 85555 15772 100.0 0.952 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba 100 74.61 3660 2975 69964 16380 100.0 1.040 !DANGEROUS LOAD-DO NOT USE!

 

[Dwh7271]

MRP and Barnes

Cartridge : .257 Weath. Mag
Bullet : .257, 80, Barnes 'TTSX'BT 25731
Useable Case Capaci: 78.990 grain H2O = 5.129 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 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 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 79 59.69 3040 1641 31848 12226 88.3 1.341
-18.0 81 61.18 3121 1730 34127 12660 90.0 1.308
-16.0 82 62.67 3203 1822 36586 13078 91.5 1.276
-14.0 84 64.16 3285 1917 39234 13477 93.0 1.243
-12.0 86 65.66 3367 2014 42089 13856 94.3 1.212
-10.0 88 67.15 3450 2114 45171 14210 95.6 1.180
-08.0 90 68.64 3533 2217 48493 14538 96.6 1.141
-06.0 92 70.13 3615 2322 52035 14836 97.6 1.104
-04.0 94 71.63 3698 2429 55814 15104 98.4 1.069 ! Near Maximum !
-02.0 96 73.12 3780 2538 59868 15337 99.0 1.034 ! Near Maximum !
+00.0 98 74.61 3862 2649 64222 15534 99.5 1.002 !DANGEROUS LOAD-DO NOT USE!
+02.0 100 76.10 3943 2761 68900 15694 99.8 0.970 !DANGEROUS LOAD-DO NOT USE!
+04.0 102 77.59 4023 2875 73931 15813 100.0 0.939 !DANGEROUS LOAD-DO NOT USE!
+06.0 104 79.09 4102 2990 79345 15896 100.0 0.910 !DANGEROUS LOAD-DO NOT USE!
+08.0 106 80.58 4181 3105 85179 15970 100.0 0.881 !DANGEROUS LOAD-DO NOT USE!
+10.0 108 82.07 4259 3222 91474 16039 100.0 0.854 !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 74.61 3966 2795 71079 15323 100.0 0.957 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba 98 74.61 3737 2481 57437 15484 97.5 1.052 ! Near Maximum !

 

[Dwh7271]

Crud.
RJ, I ran those with a 24" barrel.
If you need 26", let me know or just add a 50-80 FPS and you're probably close.
Sorry about that.

 

[Rigbymauser]

RJ,
Not the 80 (sorry) but I load the Barnes 100 with RL22 (71 gr) and it is moving right along.
Right at 3350-3400.

..thats about a .240wea. aint bad... :mrgreen:

 

[Rem Jim]

Thks Dewey - I Appreciate the info ! :grin:
Cheers RJ

 

[Dwh7271]

No problem RJ.
Glad to help.

 

[FOTIS]

If you load that 80 close to 65K psi it will break 4k

 

[HOGWILD338-378]

This was my friends chrony that I was speaking about! My jaw dropped as well :shock:

 

[FOTIS]

Friend of mine has run them over his and it was just over 4000 fps! Custom Vanguard with Mark V barrel basically ! He worked up to that really slow and not sure if he backed it down any as he probably has not!

Do you have the exact recipe?

 

[boomer68]

Wowser!! Yes, please provide load details.


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[HOGWILD338-378]

Yep the load used to achieve 4024 fps is a little hot to post numbers but I would just use book data and not push it much as most any critter will not care about you maxing a load out but RJ if ya use some of the MRP post up your results as I think that's what Norma uses anyway? I will not run that gr bullet in my rigs anyway I like the 100 & 120's ! I have a Mark V SVM in 22-250 for the Lazer work !! Likes 45 gr Vmax's and puts them in tiny holes!

 

[Dwh7271]

I've been running the 110 AccuBond w 68 MRP, CCI Mag Primers in Weatherby brass for right around 3300.

 

[Guy Miner]

I've been running the 110 AccuBond w 68 MRP, CCI Mag Primers in Weatherby brass for right around 3300.

Nice...