I've only tested the 139g GMX in my 7mm RM and Reloder 22 gave me good results. Ramshot Magnum, Reloder 22, IMR 7828, Reloder 25, and Ramshot Hunter would the powders I'd personally reach for first (and probably in that order, although I never tried Magnum with the GMX).
Here's what QuickLOAD thinks.
USE THIS LOAD DATA AT YOUR OWN RISK.Cartridge : 7 mm Rem. Mag.
Bullet : .284, 139, Hornady SST InterLock 28202
Useable Case Capaci: 75.293 grain H2O = 4.889 cm�
Cartridge O.A.L. L6: 3.290 inch = 83.57 mm
Barrel Length : 24.0 inch = 609.6 mm
Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 58000 psi, or 399 MPa
or a maximum loading ratio or filling of 103 %
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 !
64 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
--------------------------------- -----------------------------------------------------------------
Ramshot Magnum (Big Boy) 101.9 75.7 4.91 3210 98.4 58000 14001 1.138 ! Near Maximum !
Vihtavuori N560 99.2 70.3 4.56 3205 97.4 58000 14149 1.145 ! Near Maximum !
IMR 7828 SSC 98.1 69.9 4.53 3198 97.9 58000 13759 1.134 ! Near Maximum !
Accurate MAGPRO 99.5 73.4 4.76 3193 96.1 58000 14199 1.153 ! Near Maximum !
Alliant Reloder-22 99.4 69.8 4.52 3183 98.9 58000 13652 1.151 ! Near Maximum !
Winchester WXR 102.1 70.1 4.54 3181 98.8 58000 13661 1.151 ! Near Maximum !
IMR 7828 103.0 69.5 4.50 3176 97.7 56718 13684 1.146 ! Near Maximum !
Alliant Reloder-25 103.0 71.1 4.61 3146 100.0 53672 13308 1.182 ! Near Maximum !
Alliant Reloder-19 96.3 66.8 4.33 3141 98.7 58000 13001 1.146 ! Near Maximum !
Ramshot Hunter 91.9 65.9 4.27 3136 99.9 58000 12630 1.153 ! Near Maximum !
Hodgdon H414 86.8 63.7 4.13 3135 99.6 58000 12686 1.153 ! Near Maximum !
Winchester 760 86.8 63.7 4.13 3135 99.6 58000 12686 1.153 ! Near Maximum !
Alliant Reloder-17 84.6 61.6 3.99 3129 100.0 58000 11930 1.139 ! Near Maximum !
Hodgdon H4831 SC 97.6 68.5 4.44 3116 97.1 58000 12809 1.143 ! Near Maximum !
Hodgdon H4831 101.6 68.5 4.44 3116 97.1 58000 12809 1.143 ! Near Maximum !
Vihtavuori N550 88.8 63.0 4.08 3115 100.0 58000 12239 1.162 ! Near Maximum !
Accurate 4350 94.8 63.0 4.08 3110 100.0 58000 12110 1.177 ! Near Maximum !
IMR 4831 96.0 63.8 4.13 3097 100.0 58000 11866 1.167 ! Near Maximum !
Ramshot BigGame 85.3 61.1 3.96 3096 100.0 58000 11670 1.154 ! Near Maximum !
Winchester Supreme 780 95.2 69.7 4.52 3094 98.7 58000 12380 1.151 ! Near Maximum !
Vihtavuori N165 101.7 69.8 4.52 3089 99.1 58000 12188 1.156 ! Near Maximum !
IMR 4895 82.3 57.2 3.70 3087 100.0 58000 11565 1.159 ! Near Maximum !
Hodgdon H4350 93.9 63.7 4.13 3082 99.3 58000 12022 1.148 ! Near Maximum !
Alliant Reloder-15 83.2 57.7 3.74 3082 100.0 58000 11542 1.158 ! Near Maximum !
IMR 4350 92.1 63.6 4.12 3081 99.3 58000 11999 1.148 ! Near Maximum !
Hodgdon H380 84.6 60.0 3.89 3077 100.0 58000 11714 1.163 ! Near Maximum !
Hodgdon Hybrid 100V 97.2 63.1 4.09 3075 100.0 58000 11206 1.158 ! Near Maximum !
Vihtavuori N160 101.7 67.7 4.38 3072 97.7 58000 12146 1.149 ! Near Maximum !
IMR 4320 85.1 58.1 3.77 3067 100.0 58000 11155 1.144 ! Near Maximum !
IMR 4007 SSC 86.5 60.9 3.95 3064 99.3 58000 11860 1.156 ! Near Maximum !
Hodgdon H4895 80.3 55.7 3.61 3062 100.0 58000 11191 1.157 ! Near Maximum !
Hodgdon VARGET 86.1 57.8 3.74 3052 100.0 58000 11156 1.145 ! Near Maximum !
Vihtavuori N570 103.0 75.4 4.88 3043 90.4 47398 14470 1.256
IMR 4064 86.5 56.7 3.67 3043 100.0 58000 10968 1.150 ! Near Maximum !
Accurate 2520 80.2 57.3 3.72 3025 100.0 58000 10609 1.178 ! Near Maximum !
IMR 3031 82.2 53.3 3.46 3025 100.0 58000 10384 1.166 ! Near Maximum !
Accurate 3100 103.0 67.6 4.38 3020 99.6 53774 12018 1.225 ! Near Maximum !
Accurate 2700 87.7 62.8 4.07 3017 99.2 58000 11233 1.159 ! Near Maximum !
Accurate 4064 87.9 57.0 3.70 3014 100.0 58000 10570 1.197 ! Near Maximum !
Vihtavuori N150 91.7 60.1 3.89 3012 100.0 58000 10543 1.166 ! Near Maximum !
Vihtavuori N540 83.2 58.3 3.78 3006 100.0 58000 10507 1.165 ! Near Maximum !
Hodgdon H1000 103.0 70.7 4.58 2992 95.8 48383 12832 1.231
Accurate 2495 81.7 53.6 3.47 2986 100.0 58000 10184 1.202 ! Near Maximum !
Vihtavuori N140 82.9 56.4 3.66 2980 100.0 58000 10003 1.164 ! Near Maximum !
Vihtavuori N135 87.9 55.3 3.58 2966 100.0 58000 9772 1.176 ! Near Maximum !
Hodgdon Retumbo 103.0 71.9 4.66 2933 97.5 42686 13371 1.314
Vihtavuori N133 83.0 52.7 3.41 2919 100.0 58000 9223 1.161 ! Near Maximum !
Vihtavuori 24N41 103.0 76.2 4.93 2847 81.7 44480 12267 1.292
Vihtavuori N170 103.0 70.7 4.58 2826 87.7 44502 11891 1.321
Hodgdon H870 103.0 73.8 4.78 2794 88.0 37912 13027 1.402
Alliant Reloder-50 103.0 77.3 5.01 2736 83.8 35496 13129 1.464
Hodgdon 50BMG 103.0 72.6 4.70 2647 73.0 36584 11233 1.425
Hodgdon US 869 103.0 76.2 4.93 2645 77.2 36367 11297 1.433
Vihtavuori 20N29 103.0 76.9 4.98 2528 76.4 31457 11009 1.522
Accurate 8700 103.0 73.2 4.74 2492 78.0 30637 10635 1.531
Vihtavuori N32C Tin Star 93.0 32.2 2.09 2254 100.0 58000 4680 1.218 ! Near Maximum !
IMR TrailBoss 103.0 24.1 1.56 1939 100.0 37746 3645 1.476