Date: Apr 23 2020
The .450 Marlin was developed in 2000 as a joint effort between Marlin and Hornady Manufacturing. The goal was to produce a powerful load that would outperform traditional lowpressure .45-70 factory loads, while being housed in Marlin’s Model 1895 lever gun. For safety reasons, the new cartridge could not chamber in antique .45-caliber rifles. The .450 Marlin will push a 350-grain jacketed flatpoint near 2,100 fps from a 22-inch barrel, and due to its comparatively long, belted case, it will not chamber in .45-70 or .45-90 rifles.
Being a tapered straight case, the .450 Marlin requires a three-die set. For reliable chambering, cases should be full-length sized with the shell holder contacting (just slightly) the sizing die. To prevent buckling the case while seating bullets, case mouths should be flared approximately 1/20th inch to allow the bullet a “start” or begin seating.
Our test rifle features an 18 ½-inch ported barrel, which produced 1,826 fps with the 350-grain Hornady factory load, some 274 fps less than advertised speeds with 22-inch barrel. For duplicating factory loads, use Hodgdon H-4198. Results (shot to shot consistency and accuracy) with Vihtavuori N130 and Accurate AAC-2015 with the Hornady 350-grain FP were also good.