On a recent buffalo hunting trip my friend Espen gave me quite a collection of partly used boxes of various 7mm projectiles. He had worked through a wide range of projectiles until he found the projectile and load that worked best in his 7mm Rem Magnum. Incidentally, that turned out to be the 160 grain Nosler Accubond in his circumstances. He has used that load and rifle on a series of trophy hunts and is very happy with the performance.
We had been talking ballistics around the camp fire, as you do, and I had mentioned my ongoing quest to find the ideal load for my Ruger No 1 RSI in 7×57. So, over the last couple of months I have been testing a variety of those 7mm projectiles in my 7×57.
In doing that, the path seems to be leading me back to the very roots of the development of the 7×57, over a hundred years ago. I have delved into the history of the 7×57 elsewhere and won’t repeat that here. However, in brief, the 7×57 was one of the first of the smokeless military rounds, developed in the late 1800s to replace the low velocity black powder cartridges of that era. The 7×57 was developed around delivering a 175 grain projectile at a MV of 2,300 fps.
With my Ruger RSI in 7×57 I had initially loaded for the lightest projectiles in the 110, 120 and 130 grain sizes. I did that because my main quarry was the small bodied Chital deer. The accuracy was okay, as was the field performance, but I felt I could do better in that regard. For a while I loaded the 140 and 150 grain projectiles without achieving what I wanted.
I had high hopes for the Nosler Accubond. A problem there was that these are hard to obtain in Australia. Only limited supplies escape the USA and make it to our shores and those are quickly consumed. Espen was able to spare a dozen of his limited supply and I was pleased to discover that they did shoot nicely. I know already that the ABs have a great reputation for performance on game. While I was pondering how I might source a supply of my own 160 grain ABs, I decided on a whim to play about with the 175 grain Nosler Partitions that Espen had also provided.
So far, those 175 grain Nosler Partitions have shot excellent groups as I toyed with variations of load development. In doing that I have been limiting myself to three shot groups, working through different projectile seating depths as I gradually increased the powder charge all the way up to the maximum listing. As you can see, there are no signs of pressure as the powder charge was increased to maximum.
NOTE 1 – In reloading the 7×57 and the 45-70 you need to be aware that, unlike most other listed cartridges, the reloading data can vary significantly depending on the vintage and strength of the action that the reload will be fired in. Older, weaker actions cannot be safely used with reloaded rounds that are fine for strong modern actions. Some reloading guides spell this out clearly and give you loads for the different action types. Most guides don’t mention it and simply give you the lowest load that can be used in the weakest actions.
The otherwise excellent ADI reloading guide, which I most often refer to, does just that. Its data for the 175 grain 7mm Nosler Partition using AR2208 (=Varget) has a starting load of 31.0 grains for 2,005 fps at 34,200 CPU while the maximum loading is 35.0 / 2,178 / 45,500.
In this situation my fall back guide is the equally excellent manual produced by the venerable Nick Harvey. In comparison to the ADI loads above, Nick’s loads are for strong modern actions. His 7×57 175 grain starting load is 35.5 grains for 2,165 fps while his maximum is 39.5 grains for 2,470 fps.
NOTE 2 – My little Ruger No 1 RSI is similar to other Rugers I have used in the past. That is, it shoots very nicely off a cold barrel but is prone to significant group spread as the barrel warms up. Typically, it will shoot clover leaf three shot groups at 100 metres with fodder that it approves of and a cold barrel. I do not have any problem with that in a hunting rifle. I never expect to fire more than 1, or maybe 2, shots in a hunting situation anyway.
At the range this morning I was very pleased to see that the RSI seems to like the 175 grain Nosler Partition seated back at 75 thou off the lands with a maximum load of 39.5 grains of AR2208 (=Varget). I measured an average MV of 2,350 fps, which is pretty good for the stubby 20 inch barrel on the RSI.
That is another thing I have found by trial and error; hunting loads often give best accuracy when seated well clear of the lands rather than the conventional distance of 20 to 30 thou. It is something you need to test for yourself.
The ballistics achieved for the 175 grain 7×57 load give a very neat trajectory and sighting arrangement. The rifle and load can be zeroed to 175 yards and will shoot dead flat (+/- 50 mm, that is +/-2 inches) out to 200 yards.
This discovery that the RSI 7×57 seems to really prefer the 175 grain projectile actually meshes in nicely with the way my hunting is evolving. I have other calibres, firing Nosler Partitions, that are now my preference for deer hunting. I can see the 7×57 becoming my choice for pig hunting now that I am honing in on what looks to be the load for it. The short little 7×57 carbine tucks neatly away in a scabbard on my Polaris ATV, ready for action when any big old boars are encountered. In a month or two I have a boar hunting trip coming up and we shall see.