Hunting season cometh, and I decided to work up new loads for my CZ 550 American in 7x57mm Mauser. This was a special production rifle for the American market, only 100 ever having been produced. Probably to use up CZ's existing stock of 7x57mm barrels. No longer available even in Europe. CZ has a fabulous reputation for accuracy at a decent price. I was not disappointed....and the Turkish walnut stock has lots of figure....to the point that I havebeen asked, "Is that a Sako?"
The 7x57mm Mauser launches bullets at the right velocity for long soft bullets that have a very wide latitude in impact velocity, resistance of thin and thick skinned animals, game weight, and high BC for long range work out to about 600 yards. It works very well across a wide spectrum of animals and velocity, as Jack O'Connor taught and his wife Eleanor proved all over the world on a wide variety of large game. Her load used the 160-grain Speer BTSP, which fits the mold of heavy and soft which is best for the 7x57mm cartridge overall.
I have had excellent results on mule deer with the Hornady 162-grain A-MAX. While the load using IMR 4064 was accurate at load development temp in summer, it lost velocity on a cold November day and hit a bit low. It was also one null point below my Norma 150 BTSP factory load for a loss of about 300 FPE. I have since used my existing stock of Norma 150 BTSP ammo for load development benchmark. Also, I have proven by chrono that the Norma ammo from 1984 is also temp sensitive, so will not hunt with it on cold days. Factory spec of 2756 FPS at 2530FPE is reached on a warm day, but not on a cold day.
The 150-grain loads are a matched pair as far as velocity and impact point out to moderate distance. A Nosler 150 Partition over 44.0 grains of Varget seated to 3.165" C.O.L. A Nosler 150-grain Ballistic Tip seated to 3.165" over 44.5 grains of Varget. Both using Norma brass and WLR primers and Lee Factory Crimped. Note that my rifle has the long military throat and 24" barrel for the 175-grain roundnose bullets if I choose to use them. My C.O.L. is well beyond factory ammo and I am still about .100" from the lands. Long jumps do not make much difference in my rifle as long as the cartridge neck is straight and uniform thickness. Velocity of both rounds averages around 2750 FPS and energy averages around 2500 FPE. On a hot day it will chrono a bit higher than that. The Norma factory load has a higher ES and more variance with temp. My ES averages about half of Norma.
My most critical load is the Hornady 162-grain A-MAX. H4350 is the best powder for this bullet weight, and I tested H4895, Varget and H4831SC as well. The 4350 (or W760, H414) burn rate has been used by handloaders for years in the heavy bullet weights in 7mm Mauser, and that's what John Barsness uses as well. H4350 is the temp stable choice. In 150-grain weight, you could use Varget or H4350 with little difference worth fretting over. For 140-grains and lighter, use Varget, or even H4895 would work well. But 140-grains and lighter I consider a varmint bullet in my rifle. They need to be flat based to seat them far out enough to reduce jump to .100". If using lighter bullets for big game, I would go with Barnes to get a bullet long enough to include a boattail, or one of the other copper bullets. All my hunting loads use fireformed brass, not new brass. New brass is for varminting.
The Berger 168-grain VLD is reputed to work well in a fast twist 7mm Mauser, but the lower cost of the Hornady 162 A-MAX and the fact it can be jumped a lot makes it the choice for my rifle. The ballistic tip gives more consistent expansion at a wider velocity range, and the 162 A-MAX punches through considerable bone and still exits on a mule deer. At 200 yards lasered, I completely blew apart the spine in front of the shoulders on a 250-pound mule deer buck and recovered the bullet under the offside hide with 38% weight retention. On boiler room shot behind the shoulder at 150 lasered yards I had an exit hole and the lungs were turned to oatmeal. Death comes quickly to mule deer with a good hit from a Hornady 162 A-MAX. A similar neck/spine shot just in front of the shoulder on a smaller buck the previous year at 75 yards using a Nosler 150 BT in Winchester .308 caused complete destruction of the bullet, no exit, no large pieces of bullet found (biggest piece was the green plastic tip), and a lot of ruined neck meat and shoulder meat. The 7mm Mauser kills without destrying as much meat, and can do so at a much longer range due to a 162 A-MAX BC of .625 vs. .453 for the .308 Nosler 150 BT.
My Hornady 162 A-MAX load is 47.0 grains of H4350 seated to a C.O.L. of 3.240" in R-P brass using a WLR primer. My primers are the old nickel plated Winchester primers, since I have a lifetime stash of them. The load chronographs at 2683 FPS with energy at 2590 FPE. None of my loads have flattened or cratered primers. Brass growth requiring trimming is almost nonexistent after fireforming and initial trim. My rifle is made to handle the 65,000 PSI of the .270 Winchester round. I can go 200 rounds without decoppering my barrel, after initial break-in. The 7mm Mauser is still a battle rifle par excellence that most people can shoot accurately. Try that with your 7mm Magnums. Also, you will have to take a very long shot with a soft bullet in a 7mm Mag or risk blowup. Mine goes about zero to 600 yards with no worries. I still outshoot the young guys with their .300 RUM rifles at the shooting range. I need to start taking their money on bets.
Nathan Foster has done a lot of work with the 7mm Mauser and describes the bullets I have used in more detail, and a lot of other bullets besides. His website proved extremely useful to me in load development. You can read all about it at www.ballisticstudies.com
The 7mm Mauser still rocks, if you handload and do it correctly. All of my loads achieve 5-shot groups of 1" at 100 yards with no long wait between shots on a rather windy Montana day. Strong sidewinds will sprread the groups a bit beyond that horizontally. My first three shots with 150 BT yesterday was 3/8" at 100 yards with a cold barrel, no wait between shots, just like a hunting situation. Wind was gusting strongly headon, quartering somewhat to my right. I do not prescribe to working up loads on "perfect" days. I want to know how loads work under various conditions, just like in hunting.