.30-06 Ackley Improved: new loads for the “miser’s magnum”

The .30-06 Ackley Improved is well named “the miser’s magnum” as it’s a highly efficient cartridge hot on the heals of the .300 Winchester Magnum, especially in the right rifle.

I knew it was good but I’ve now developed some new loads for it which prove it is a great performer, particularly with the heavier .30-calibre bullets.

The .30-06 is a quiet achiever. One of the most controversial wildcats ever developed from it was PO Ackley’s .30-06 Improved. 

Two schools of thought clashed heatedly over the cartridge; one group claimed it was little better than the standard .30-06 while another school argued that it was as good as the .300 H&H magnum, at that time the sole popular commercial .30-cal magnum. 

One writer, tongue in cheek, christened it “the miser’s magnum”.

Several issues fuelled controversy over the wildcat’s performance. One was the lack of handloaders’ chronographs, which led to experimenters guesstimating the velocities they were getting. 

Another was that there wasn’t a wide choice of suitable slow-burning propellants back in the early days.

In 1980 I set out to separate fact from fiction. According to the five pages of data in my log, the velocities I got with my original .30-06 Ackley were impressive but I was relying on a chronograph with a binary read-out that I am dubious about today.

Still, the conclusion I reached was that the .30-06 Ackley was a well-balanced and very efficient wildcat and that its volume was probably better suited to the .30 bore size than the .30-calibre belted magnums of the day.

This only increased my desire to verify my old results.

THE RIFLE: A CUSTOM WINCHESTER MODEL 70

The rifle I’ve built is based on a new stainless Winchester Model 70 action, a stainless Pac-Nor barrel with Model 70 Featherweight profile and a Model 70 Extreme Weather synthetic stock. 

The chamber has a throat length that allows me to seat 180gn bullets slightly above the base of the neck. This throating allows a cartridge length of 3.315” (84.2mm), the maximum overall cartridge length which will fit in the magazine of the Model 70.

I had two pillars inserted in the stock, and the recoil lug and first two inches of the barrel are bedded in epoxy, leaving the rest of the barrel floating. 

The lightweight barrel has a 1:10” twist and a length of 25 inches which provided a light hunting rifle, one that carries easily and packs a considerable punch for all deer species including sambar.

FIRE-FORMING CASES TO .30-06 AI

Cases for the .30-06 Ackley are easy to form simply by firing factory ammo in the improved chamber, or by loading virgin brass with a charge 2gn less than the listed maximum load for the standard .30-06. 

The best results are gained using a snappy load so that when the rifle is fired, body taper is greatly reduced, and the shoulder fills out to form sharp edges accompanied by increased powder capacity.

The load I used for fire-forming Sellier & Bellot .30-06 cases was 55gn of AR2209 behind the 180gn Sierra boat-tail seated to an overall cartridge length of 3.315” (84.2mm). This length only just fitted into the Model 70’s magazine. 

Forty cases were fire-formed without losing a single one.

Headspace of rimless cartridges is generally measured from the face of a locked bolt to some point on the shoulder called the datum line, and industry standards set allowable headspace at .004” (0.1mm) maximum, but headspace in an improved cartridge must be considerably less than what is normally regarded as minimum.

When cartridges are inserted in chambers having relatively the same shoulder angle they are bound to make contact at some point on the shoulder, but this is not possible when a factory cartridge enters an improved chamber because it will be fired in a chamber radically different from the standard chamber, which is a close fit to the cartridge itself. The only point of contact in the improved chamber is going to be exactly at the junction of neck and shoulder, which calls for practically nil headspace.

In the standard .30-06 the bolt should close on a 1.940 go-gauge but refuse to close on the 1.946 no-go gauge to ensure headspace is within the allowable limits (.004-.006”, or .1-.15mm). With the Improved cartridge the 1.940 gauge becomes to the no-go gauge, and the go-gauge must be approximately .004” shorter, or 1.936. 

Ideally, when fire forming a standard .30-06 cartridge to .30-06 Ackley, the bolt should close with a slight ‘feel’.

Today, ballisticians are convinced that the sharp 40-degree shoulder that Ackley favoured creates greater resistance to the burning powder by holding more of it back in the case during the burning process. 

Reducing the amount of unburned granules being blown out into the chamber throat decreases erosion. 

A straight-bodied case with minimum body taper combined with a sharp shoulder also slows the forward flow of brass, reducing the number of times cases will need trimming.

DEVELOPING MAXIMUM LOADS

Maximum loads were developed using Sellier & Bellot cases from the same lot. Powder charges were increased one grain at a time. When excessive pressures were encountered, the charge was reduced by one grain and five shots were fired.

The pressure ring on each one of the fired cases was measured and the readings averaged. That reading was then considered the maximum reading for all the rounds fired. 

The loads I’ve listed in the table are working loads and below maximum, but for other rifles, start at least three grains below and work up one grain at a time.

The secret to safe handloads is good case life and snug primer pockets. In no instance was it hard to extract a case and I could literally lift the bolt handle with one finger.

A couple of tips: when working with maximum handloads, the sizing die should be set so the case fits the chamber with absolute minimum clearance. If the sizing die is set properly, the case head will not slam against the bolt face and register erroneous pressure indications, nor will case head separations become a problem.

In addition, be sure that all sizing lubricant is removed from the cartridge cases. Any oil or residue on the case prevents the case from gripping the chamber wall. A slippery condition within the chamber will increase bolt thrust considerably, and high bolt thrust can be dangerous, particularly when working with high-pressure loads.

DEVELOPING FAST, ACCURATE LOADS

My tests were carried out under conditions that were as controlled as most handloaders can obtain. I fired from sandbags on a bench over a Chrony chronograph, measuring the velocity and shooting for accuracy at the same time.

As I worked up loads gradually, I was not surprised to find that the best accuracy came with maximum or near maximum loads for each combination of powder and bullet. 

The light Pac-Nor barrel gave good hunting accuracy with every weight of bullet I tried, which I attributed to the neat chambering job and a ratio of powder capacity to bore capacity that’s not too high.

The best powders in the .30-06 Improved were a pair of slow burners: AR2209 and AR2213SC. 

AR2217 proved too slow and I couldn’t get enough in the case.

Velocities from the .30-06 Improved using these slower-burning powders were well ahead of what I obtained in a maximum-loaded .30-06.

I read pressures by measuring case head expansion.

150 GRAIN BULLETS

I got my highest velocity in a standard .30-06 with 24” barrel: 3015fps with the Woodleigh 150gn bullet, 60gn of AR2209 and the CCI 250 primer in a Super-X case; it’s a maximum load.

The 25” .30-06 Ackley Improved made 3210fps with the Barnes 150gn TSX, 63gn of AR2209 and CCI 250 primer in fire-formed Sellier & Bellot cases. 

That’s 195fps faster than the standard .30-06 does at its best.

The tightest groups, however, were obtained with 62gn of AR2209 with the 150gn Barnes TSX, which delivered 3164fps with groups averaging .890. That’s still almost 150fps faster than the standard .30-06.

165 GRAIN BULLETS AND UP

My main interest in the Improved .30-06 focused on the Nosler 168gn Bonded Solid Base bullet for general deer hunting. With polymer tip, tapered copper alloy jacket and boat-tail base, the 168gn bullet shoots flat and carries increased striking energy away out yonder.

In the .30-06 AI my maximum load reached 3064fps with the 168gn Nosler BSB and 61gn of AR2209. That gives the old timer a major boost: maximum load of 57gn of AR2209 in the standard .30-06 barely turned up 2843fps; I got 2799fps with Barnes 168gn ELD-X and 58gn of AR2209.

In the Ackley Improved, the slightly lighter 165gn AccuBond clocked 3175fps, hard-driven by 62gn of AR2209, and it shot nice, round sub-MOA groups.

As testing progressed it became apparent that the sharp-shouldered, straight-walled Improved case is capable of significantly higher velocities and becomes more efficient with bullets weighing 165gn or more, without excessive pressures.

Evidently, the sharp shoulder of the case causes more complete burning of the powder, whereas lighter bullets can be urged down the barrel before the powder is completely combusted.

For instance, the Improved drives the 180gn Norma bullet at 2945fps with a maximum charge of 64gn of AR2213sc. This was yet another accurate load, too.

In the standard .30-06, I achieved 2750fps with the 180gn Woodleigh and 47gn of AR2209, a maximum load.

These are spectacular velocities for 168 and 180gn bullets, which are the most useful weights. 

A strongly structured 165-168gn projectile is, in my estimation, just as effective as the 180gn. It starts out 100fps faster than the 180gn, but there is little difference in drop at 400m and it delivers pretty much the same amount of energy as the 180gn depending on the shape of the bullet used.

The .30-06 Ackley Improved is capable of driving 200gn bullets at 2800fps with excellent accuracy. AR2213sc is the top powder choice; 63gn drives the Lapua 200gn Mega at 2802fps. This just might be the most ideal bullet weight for all-round shooting of tough big-game animals in heavy cover.

The 180gn spitzer with a muzzle velocity of 3000fps will have almost the same impact point at 200m as the 200gn at 2800fps. However, the 200gn reaches 200m packing about 200ft-lb more energy than the 180gn and has more penetration and bone-smashing ability.

THREATENING THE .300 WINCHESTER MAGNUM

Experienced hunters who swear by the .300 Winchester Magnum should take notice. The .30-06AI comes close while using a lot less powder. 

The belted case needs 78gn of powder to give the 165gn bullet 3250fps; 75gn to give the 180gn 3100fps, and the 200gn 2950fps. 

In general then, the Improved trails the .300 Win Mag by about 100-150fps, but the magnum needs 10-20gn more powder and a 26-inch barrel to hold its advantage.

CASES AND CAUTIONS

Observe the usual precautions when handloading this wildcat: differences in the case capacities of different makes of brass can affect maximum loads. 

I used Sellier & Bellot brass which is normally slightly heavier and holds a bit less powder than some other brands, but the difference is not carved in stone, so be sure to check case volume if you change brands.

After fire-forming in the Improved chamber, the S&B case holds four more grains of powder than standard S&B .30-06 brass. So don’t interchange brass without dropping back three grains and working up again. 

Using slow-burning powders, the safest loads are high-density ones which leave little or no air space in the case.

LOADS FOR THE .30-06 ACKLEY IMPROVED