7x64 vs 7x57 Ackley Improved

[Heym SR20]

Thanks for posting this. Interesting to see the 7x64 can be loaded to give similar velocities with 170gn bullets as with factory 140gn in some rifles.

I am just looking at a box of RWS 7x65R cartridges. These were loaded with 177gr ID Classic Bullets (the old Brenneke style double core bullet) with a muzzle velocity of 2690 fps and energy of 2844 ft lbs. Recomended zero distance (MRD) is 185 yds, which is 1.6" high at 100, -0.7" at 200 and -4.5 at 250.

Also have the 140gn RWS HIT - MV 2917 fps, 2653 ftlbs of energy, Trajectory - MRD 209 yds, 1.6" high at 100, 0.4" at 200, -2.2 at 250. In other words flat shooting.

The 7x65R is the rimmed sister of the 7x64 and is typically loaded to about 10% less pressure.


By contrast I also have an old box of 7x57 RWS loaded with a 162gn ID Classic bullet - MV 2620, and 2469 ft lbs, trajectory MRD 179 yds, 1.6" at 100, -1.1 at 200 and -5.4 at 250.

Both the 7x64 and 7x65R are widely used in Europe and used on everything from small Roe through to mountain Chamois to big forest red deer and boar, and even Brown Bear. They are also popular in Namibia. You have all the power of the 30-06 if needs be, but usually with less recoil and a flatter shooting bullet. Certainly with a 139gn bullet my lightweight combination gun is a delight to shoot, but with a 177gn H-Mantle or ID Classic Bullet it has some serious thump, but also still pleasant to shoot.

In real terms sight either a 7x57 or 7x64 1 inch and a bit at 100yds and you really only need to worry about distance as you start going past 200 yds.

 

[scrumbag]

I have been pleased with RS70 in my experimentation with heavier bullets. Seems to give a similar performance to RL26 but often with a bit less of a full case.

I have Chronoed 53.3 gr of RS70 with a 180gr Hornady ELD-M at just over 2800 fps. (That is from a 26" and if you use this load you do so at your own risk).

 

[CerebralDistortion]

Late to the party perhaps...

I find the AI interesting, where applicable. For instance a 308 Win is not a winner in AI, there simply isn't enough things happening with that cartridge to justify the process.

Older, turn of the 18 th century older, cartridges benefit more. The 6.5x55, 7x57 and 7x64 share characteristics. All are fairly conical, have about the same shoulder angle and are intended for heavy for caliber round nose bullets. These benefit being Ackleyfied since powder capacity goes up by a significant number.

They also are able to handle heavy spitzer bullet quite well since they have quite a generous freebore. However, since they originally all use a rather slow twist, not all barrels are suitable.

I myself considered going 7x64AI replacing an old 6.5x55, but that is not a CIP/SAAMI round and since there are an alternative that is, I went with a 280AI instead. The freebore is not as long, but I'm using lead free spitzers not roundnose lead bullets.

With a long enough barrel it is possible to get about 3400 fps with a 140 gr bullet. Not that I have any intention to, but others might. I went with the 280AI for flair and brass life with moderate loads.

Edit:
Quite a windy preamble, so I forgot the question...

7x57 loaded to modern pressures in a rifle that can handle them, about equals the performance of a 7mm-08 or 308 Win. Getting a 7x57AI because you want one is a viable reason. Getting one for performance gains isn't.

 

[levigsp]

Late to the party perhaps...

I find the AI interesting, where applicable. For instance a 308 Win is not a winner in AI, there simply isn't enough things happening with that cartridge to justify the process.

Older, turn of the 18 th century older, cartridges benefit more. The 6.5x55, 7x57 and 7x64 share characteristics. All are fairly conical, have about the same shoulder angle and are intended for heavy for caliber round nose bullets. These benefit being Ackleyfied since powder capacity goes up by a significant number.

They also are able to handle heavy spitzer bullet quite well since they have quite a generous freebore. However, since they originally all use a rather slow twist, not all barrels are suitable.

I myself considered going 7x64AI replacing an old 6.5x55, but that is not a CIP/SAAMI round and since there are an alternative that is, I went with a 280AI instead. The freebore is not as long, but I'm using lead free spitzers not roundnose lead bullets.

With a long enough barrel it is possible to get about 3400 fps with a 140 gr bullet. Not that I have any intention to, but others might. I went with the 280AI for flair and brass life with moderate loads.

Edit:
Quite a windy preamble, so I forgot the question...

7x57 loaded to modern pressures in a rifle that can handle them, about equals the performance of a 7mm-08 or 308 Win. Getting a 7x57AI because you want one is a viable reason. Getting one for performance gains isn't.

Very interesting reply but some confusing info. you say the likes of 7x64 benefit being Ackleyfied, then say "They also are able to handle heavy spitzer bullet quite well since they have quite a generous freebore". and then go on to say "However, since they originally all use a rather slow twist", not all barrels are suitable.". sorry but i have never seen a 7x64 with slow twist, but the opposite. You say the 308 win is not a winner, and later say "I went with the 280AI for flair and brass life with moderate loads." so its not always about maximising case capacity! I have 308 win Ai and its a winner , but that's down to being able to utilise a Russian powder that did nothing unusual in standard 308win but is remarkable in AI and case life, recoil etc are all altered. I love my AIs for a number of reasons and will build more.

 

[CerebralDistortion]

Very interesting reply but some confusing info. you say the likes of 7x64 benefit being Ackleyfied, then say "They also are able to handle heavy spitzer bullet quite well since they have quite a generous freebore". and then go on to say "However, since they originally all use a rather slow twist", not all barrels are suitable.". sorry but i have never seen a 7x64 with slow twist, but the opposite. You say the 308 win is not a winner, and later say "I went with the 280AI for flair and brass life with moderate loads." so its not always about maximising case capacity! I have 308 win Ai and its a winner , but that's down to being able to utilise a Russian powder that did nothing unusual in standard 308win but is remarkable in AI and case life, recoil etc are all altered. I love my AIs for a number of reasons and will build more.

If I'm confusing you, or sound confused, it is not my intention.

My consideration is this: Ackleyfied cartridges does not specify twist. For example, taking an existing 7x64 and reaming it to AI leaves it with the old twist. Building a new rifle and ordering a barrel with a 1:8 twist opens up the possibility to use for example Barnes TTSX 175 gr or Barnes 195 gr Elite Hunter that might not stabilize in the old 8.66:1 (7x64 might not be the best example since the twist quite fast and other examples might be better, but I'm being general).

Long spitzer bullets can be loaded longer if the freebore admits it which is in no way related to the twist rate of the barrel.

The 280 Rem is among the top modern cartridges to Ackleyfy. About 16% capacity and 4% performance.

The capacity increase of the 308AI compared to 308 Win is negligible.

Good that the 308AI worked for you, but as soon someone start mentioning magic components I'm rather sceptical. Sound as if you are loading sensible loads at sensible pressure which reduces recoil and extends brass life so...

 

[Ratwhiskers]

The standard sammi .308 is rated to 62,000psi (the .270win is rated at 63,000psi), so trying to run it at greater pressures can incur problems. Now AI it and run a powder that may have been a touch (doesn't need much) too slow but now in the Al case and prestadigito a winner is born, and again at similar pressures to the parent. Does that mean it's any better, maybe not, just different, that's why some of us are inclined to peer down rabbit'oles, we find interest in what may be found there.

As has been said, it's not all about pure velocity gains, there's more tied up in it then that.

The old 7x57 loading asked for a p-max of 51,000psi, where the modern loading for rifles in good condition is 56565psi and the 7-08rem' runs at a tad over 60,000psi. All giving the modern 7x57 a large window for loadings and a decrease in pressure against it's rivals.

Brass can have differing capacities, barrel lengths are not always the same against other rifles tested, twist rates can be altered as can throat dimensions, some powders/primers/bullets may or not be available.
These are just some of the variables we face when wandering down country lanes in search of nirvana

 

[scrumbag]

I’m always amazed by the difference running 257 Roberts at regular pressures produces

 

[JockStalk]

I love my 7x57 as much as anyone, but no idea why you would want to bother ‘improving’ it. 145gr Speer and a sensible load of N150 runs at 2850 in mine. If I pushed it harder it would end up a loud, pushy, snappy thing. If I wanted that I could buy a 270, or drive over to the mother in laws.

 

[Ratwhiskers]

JS, l agree sir, on all counts!!

My 7-08 runs 120's at a shade under 2900ft/sec which makes it a wonderful think to use, why do l need to tweak it all the way up to 3200ft/sec just because the book says l can. My next 7mm might well be a 7mmBR so hardly a fire breather.

Now, where did l put that tub of Trail Boss.....??!!