Updated: a day ago
The owner himself will post the steps he is planning for testing the rifle - and maybe talk about his proposed visit. I am simply opening the door for his missives out of Virginia. Congratulations with the rifle, Kennis - we are looking forward to the posts and photos.
Here is his first factory ammunition to get a feel for the rifle and see where it puts the bullets, as well as building a muscle memory data base for eventual accurate off-hand shooting.
Initial comments were that the bullet appeared to be small.. but that is merely in relation to the fat case of the .375 Ruger.
We should see the Ruger M77 Alaskan here by tomorrow.
The Ruger Alaskan with its Hogue stock has arrived!
The .375 Ruger is a very well thought out cartridge regarding propellant volume / maximum pressure / muzzle velocity. It is shorter than the .375 H&H but its wider body with less tapered sides allows for a slightly higher propellant volume. The neck of the Ruger case is shorter, letting the same weight bullet protrude a little more into the propellant volume.
Full water volume for the Ruger case is 64.35 cc, and the H&H is 61.95 cc. This allows the Ruger to have a slight theoretical edge over the .375 H&H regarding velocity yield over grain of propellant charge. This is called the V/C ratio and the dynamic part of the two-part concept is an extremely important factor for the reloader to consider when developing a load with reference to published reloading tables - specifically when doing incremental additions at the upper performance levels.
Relating to the above, here are some salient specifications of the .375 Ruger cartridge based on C.I.P. defaults:
P.Max: 62,004 psi (.375 H&H: 62,366 psi).
Cartridge Overall Length: 84.84 mm (.375 H&H: 91.44 mm).
Rim diameter: 13.51 mm (.375 H&H: 13.51 mm).
Velocity, Pressure and V/C factor with Somchem propellants:
Ruger: 300gr Swift A-Frame: 68 gr.S341: 2,482 ft/sec. @ 58,110 psi V/C: 36.5.
H&H: 300gr Swift A-Frame: 70 gr.S341: 2,526 ft/sec. @ 60,961 psi V/C: 36.1.
Ruger: 300gr Swift A-Frame: 72.5 gr.S365: 2,580 ft/sec. @ 61,617 psi. V/C: 33.9.
One advantage of a cartridge that has better VC potential is that it can duplicate the performance of the other but at lower chamber pressure. This is the principle of the South African .458 3" Express over the .458 Lott, and the .458 Sabi over the .460 Weatherby Magnum.
Look at the mere 26 ft/sec difference in MV above between the two cartridges, each using the double based Somchem S341 propellant: the Ruger achieving virtually the same velocity as the .375 H&H but needing 2,851 less psi and 2 gr less propellant.
Obtaining the same muzzle velocity with lower maximum chamber pressure means there was longer but slower rate of acceleration of the bullet, which means the recoil force will be lower (force = mass x acceleration). The on-shoulder recoil effect of this Newtonian derived law of physics is most noticeable in the .416 Rigby vs. the .416 Ruger and the .416 Remington Magnum, and even between the .416 Ruger and the .375 H&H in rifles of similar weight and stock design.
I have no experience of the Ruger but my guess is the recoil slap will be slower and lower than a .375 H&H from a similar rifle at similar velocity with the same propellant and bullet.
Readers are invited to share their own experiences with the .375 Ruger in the "Comments" section as Kennis introduces us to this Ruger M77 Hawkeye, the Hogue stock, the suitability of the recoil pad for field use, and of course what he experiences from the ammunition he uses.