.257 Wby Mag

B

Browning_300wsm

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Eastern Ontario
What would be the best powder to start loading the
257 Weatherby. From the reading I've done it looks like IMR 7828 or RL-25? I'll mainly be loading 100 and 110gr bullets. May experiment a bit with 75 and 87s. Thanks for the input!
 
Code: 
Cartridge          : .257 Weath. Mag
Bullet             : .257, 110, Nosler AccuBond 53742
Useable Case Capaci: 76.606 grain H2O = 4.974 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 mm
Barrel Length      : 26.0 inch = 660.4 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 60000 psi, or 413 MPa
or a maximum loading ratio or filling of 104 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

177 loads produced a Loading Ratio below user-defined minimum of 80%. These powders have been skipped.
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------

Hodgdon Retumbo                    102.6     72.9     4.72    3549   100.0    60000   14916   1.125  ! Near Maximum !
Alliant Reloder-33                 100.7     77.2     5.00    3538    96.3    60000   16456   1.148  ! Near Maximum !
Alliant Reloder-26                  87.0     66.1     4.28    3495   100.0    60000   14319   1.151  ! Near Maximum !
Alliant Reloder-25                  95.8     67.3     4.36    3493   100.0    60000   14054   1.136  ! Near Maximum !
IMR 7828                            94.8     65.1     4.22    3481    99.0    60000   14700   1.129  ! Near Maximum !
Hodgdon H1000                       99.8     69.7     4.52    3479    99.3    60000   14450   1.122  ! Near Maximum !
Accurate MAGPRO                     90.8     68.1     4.41    3469    97.5    60000   15217   1.145  ! Near Maximum !
Alliant Reloder-22                  90.7     64.8     4.20    3456    99.6    60000   14481   1.144  ! Near Maximum !
Ramshot Magnum                      90.8     69.9     4.53    3437    99.9    60000   13919   1.142  ! Near Maximum !
Alliant Reloder-19                  88.5     62.5     4.05    3420    99.6    60000   13886   1.139  ! Near Maximum !
Alliant Reloder-23                  92.4     63.8     4.13    3412   100.0    60000   12957   1.154  ! Near Maximum !
Ramshot Hunter                      84.2     61.4     3.98    3407   100.0    60000   13320   1.146  ! Near Maximum !
Hodgdon H4831                       93.6     64.3     4.16    3400    98.4    60000   13827   1.137  ! Near Maximum !
Alliant Reloder-16                  85.0     58.4     3.79    3398   100.0    60000   12731   1.151  ! Near Maximum !
IMR 4955 Enduron                    91.7     63.0     4.08    3370    98.6    60000   13445   1.138  ! Near Maximum !
Hodgdon H4350                       86.9     60.0     3.89    3362    99.9    60000   12882   1.143  ! Near Maximum !
IMR 4350                            85.3     59.9     3.88    3362    99.9    60000   12853   1.143  ! Near Maximum !
 
100 gr Tsx barns out of my rifle was accurate with H1000, just couldn't get the speed I wanted before finding pressure signs..
Went to IMR 4831 and BR2 large rifle primer.. didnt think a magnum primer was necessary to ignite IMR around the 70 grain mark in warmer weather.. also a good crimp.
75 grain bullets, its tuff to beat R22 and H4831SC..
Although I have not tried H 380 , data is in the 50 edition lyman
Manual,, maybe this spring..
Wish I had Todd's computer skills.. nice chart
 
Laugh at me if you will but I load mine with imr 4064. I found the load in an old speer manual, I think #6. My 87 gr bullets group under .5 when I'm having a good day and they move fairly fast over the chronograph
 
Retumbo and Vihtavuori N570 work well in my 257 Weatherbys when using bullets from 110-120 grains.
I also have a very good load with IMR5010, but that is a moot point, since this powder is obsolete. D.
 
I’ve used both 4831s, H1000 and 7828 with great success.

What I’ve found about with Weatherby cartridges is its all about the bullet. If your barrel hates a particular bullet it’ll hate it with every powder. If it likes a bullet it’ll like it with every suitable powder.
 
IMR 7828. My 257s love it. I usual shot a few rounds of factory ammo to see what a gun likes then start loading from there. I have found that Weatherby has their ammo figured out so I usually then load to a similar COL.
 
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