7mm 175gr Eld-X 18 in 1-8 twist barrel

[Tjangevine33]

So I'm looking into building a ultralight hunting rifle using a 7mm rem mag cartridge. Throwing a 175gr ELD-X projectile. But due to it not being the best length of barrel there's not any load data out there for it.
I'm hunting at around 9000 ft of elevation with an average temp of around 40-50°. C.O.L of 3.290" and h2o of 77 gr.

 

[desertcj]

I’m interested to see the data but because of the 18” barrel, my guess is that it won’t be much better than a 7mm-08.

 

[TackDriver284]

I just picked one of the top powders for the 7mm Magnum and used RL22 to get an idea on velocity. the only con is the 18 inch barrel length which brings the speed down close to 7mm-08 speeds with 24-26 inch barrels.

Cartridge          : 7 mm Rem. Mag.(SAAMI)
Bullet             : .284, 175, Hornady ELD-X 2841 G7
Useable Case Capaci: 65.293 grain H2O = 4.239 cm³
Cartridge O.A.L. L6: 3.290 inch = 83.57 mm
Barrel Length      : 18.0 inch = 457.2 mm
Powder             : Alliant Reloder-22 *C

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   90    54.90   2374    2189   43882  15454     94.5    1.235
-09.0   91    55.51   2402    2242   45364  15661     95.0    1.215
-08.0   92    56.12   2431    2296   46890  15863     95.5    1.196
-07.0   93    56.73   2460    2351   48462  16060     96.0    1.177
-06.0   94    57.34   2488    2406   50086  16251     96.4    1.158
-05.0   95    57.95   2517    2462   51764  16437     96.9    1.140
-04.0   96    58.56   2546    2519   53499  16616     97.3    1.122  ! Near Maximum !
-03.0   97    59.17   2575    2576   55292  16790     97.6    1.104  ! Near Maximum !
-02.0   98    59.78   2603    2634   57145  16957     98.0    1.086  ! Near Maximum !
-01.0   99    60.39   2632    2692   59063  17117     98.3    1.069  ! Near Maximum !
+00.0  100    61.00   2661    2751   61045  17270     98.6    1.053  !DANGEROUS LOAD-DO NOT USE!
+01.0  101    61.61   2690    2811   63096  17417     98.9    1.036  !DANGEROUS LOAD-DO NOT USE!
+02.0  102    62.22   2718    2872   65219  17555     99.1    1.020  !DANGEROUS LOAD-DO NOT USE!
+03.0  103    62.83   2747    2933   67415  17686     99.3    1.004  !DANGEROUS LOAD-DO NOT USE!
+04.0  104    63.44   2776    2994   69689  17809     99.5    0.988  !DANGEROUS LOAD-DO NOT USE!
+05.0  105    64.05   2805    3056   72043  17924     99.7    0.973  !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    100    61.00   2796    3037   73687  16911    100.0    0.968  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    100    61.00   2478    2386   48766  16629     92.3    1.163

 

[Charlie-NY]

Load data for short barrels is no different than for standard length barrels. A powder that produces the highest velocity in a long barrel will usually produce the highest velocity in a shorter bbl. The only difference is the reduction in velocity. You may get an awful lot of muzzle flash from an 18" bbl with some powders. That could be a consideration with your powder selection.