Power to burn; Hodgdon's IMR 4007 SSC propellant proves its worth across an all-American assortment of hunting cartridges.
Improved Military Rifle powders have been a handloading staple for decades, but in recent times the brand had become stagnant. Hodgdon Powder Company purchased IMR a few years back, took stock of things and began successfully restoring the brand to its previous luster. Hodgdon continued production of the original IMR powders and updated the information pipeline by including pressure-tested data on its website. The company also introduced new IMR powders to fill specific niches, and IMR 4007 SSC is one of them. "SSC" stands for "Super Short Cut," and the small, stubby kernels are a natural for powder measures.
The .243 Winchester and .30-06 do great with IMR 4007 SSC, ay do the .220 Swift and .22-250. With lighter bullets, it also does well in the .270 Winchester, .300 Winchester Magnum and the WSMs. The .224, .243 and .25 Super Short Magnums from Winchester also perform well with IMR 4007 SSC due to its small grain size, high energy content and uniform ballistics.
IMR 4007 SSC kernels are .051 inch long by .040 inch in diameter, and its bulk density is 910 g/1. These dimensions are considerably smaller than the traditional long-stick IMR powders. This means that with proper charges, load densities are right up there, and most of the case volume is filled--good for uniform ballistics and accuracy.
IMR 4007 SSC's burning rate is between Varget, Ball-C(2) and H-380 on the fast side and W-760 (and its ballistic twin, H-414) on the slow side. Of the IMR series, it sits between 4064 and 4350.
Before I prepared any test loads with IMR 4007 SSC, I wanted to check out how it flows through a powder measure, so I threw 20 charges through an RGBS Uniflow and weighed them. The average was 41.0 grains, the ES was only .20 grain, and the SD was a miniscule .09 grain. This powder is a natural for thrown--rather than weighed--charges.
I reviewed a mass of load data to get a feel for how IMR 4007 SSC fits in the scheme of things and discovered that it works best with small-to medium-size cartridges and delivers near-top velocity for a given round with lighter-weight bullets. For example, in the .22-250 with the 50-grain Sierra softpoint, 40.2 grains of IMR 4007 SSC gave the highest velocity of any powder listed--3,945 fps. Ditto with the 55-grain Speer softpoint (3,713 fps, tied with IMR-4064). Moving to the 63- and 70-grain bullets, velocities with IMR 4007 SSC taper off only slightly.
In the .270 WSM, velocity of the 90-grain Sierra HP with 66 1/2 grains of IMR 4007 SSC was 3,708 fps, or 98 percent of the maximum listed (3,789 fps with 68.0 grains of H-414). The heaviest bullet listed for this cartridge with data for IMR 4007 SSC is the 150-grain Hor-nady. Over 56.0 grains, velocity is 2,982 fps, or 94 percent of maximum.
I rounded up some representative rifles in suitable calibers and ran a few hundred IMR 4007 SSC handloads over the chronograph. As I prepared test loads, I was impressed with how easily IMR 4007 SSC flowed into the cases and the relative amount of volume left. Only occasionally was a charge slightly compressed. Velocities were impressive, and overall accuracy was at least as good, and often better, than loads previously fired in the test guns.
Rather than shoot a few rounds through a lot of guns, I flipped around that paradigm and tested IMR 4007 SSC with a few representative loads in cartridges Hodgdon lists as ideal--the .220 Swift, .243 Winchester, .30-06 and .300 Winchester Magnum. Then I gave it an in-depth workout in the .25 WSSM in a new AR. Let's get to the nitty-gritty..220 SWIFT
SELECTED IMR 4007 SSC HANDLOADS* Charge Bullet COL ** Velocity SD Group (gr.) (in.) (fps) (in.) .220 Swift, Ruger M-77R, 24-inch Barrel 41.5 Speer 50-grain Soft Point 2.682 3,802 12 .76 40.4 Hornady 55-grain Soft Point 2.680 3,785 15 .81 39.2 Nosler 60-grain Partition 2.683 3,523 21 .92 38.0 Sierra 63-grain Semi-Spitzer 2.675 3,440 19 .86 .243 Winchester, Browning A-Bolt II, 22inch Barrel 47.0 Nosler 55-grain Ballistic Tip 2.550 3,234 22 .98 45.0 Speer 70-grain Hollow Point 2.620 3,422 23 1.04 43.6 Sierra 80-grain Spitzer Boat 2.600 3,220 22 1.00 Tail 36.5 Hornady 105-grain A-Max 2.745 2,732 20 .98 .25 WSSM, Olympic Arms K8-Mag, 24-inch Barrel 47.5 Hornady 75-grain Hollow Point 2.16 3,229 14 .87 45.6 Sierra 87-grain Spitzer 2.25 3,036 17 .73 45.6 Sierra 90-grain Hollow Point Boat 2.16 3,043 17 .97 Tail 44.1 Barnes 100-grain TS-X Boat Tail 2.25 2,906 15 .88 44.1 Hornady 100-grain Soft Point 2.25 2,940 4 .81 InterLock 44.1 Nosler 100-grain Partition 2.25 2,946 21 1.04 44.1 Sierra 100-grain Spitzer 2.25 2,903 8 .91 44.1 Swift 100-grain A-Frame 2.25 2,923 24 .98 42.8 Swift 100-grain Scirocco II 2.25 2,909 13 1.03 42.5 Hornady 110-grain InterBond 2.25 2,806 15 .98 42.5 Nosler 110-grain AccuBond 2.25 2,825 22 .67 40.7 Nosler 115-grain Ballistic Tip 2.25 2,654 26 .85 41.0 Hornady 117-grain Boat Tail Soft 2.25 2,700 16 .59 Point 41.0 Sierra 117-grain Spitzer Boat 2.25 2,696 7 .87 Tail 40.4 Speer 120-grain Hot-Cor Soft 2.25 2,686 15 .79 Point - Winchester 110-grain Bonded 2.34 2,989 19 1.50 (Factory) - Winchester 115-grain Ballistic 2.34 3.022 14 1.06 Silvertip (Factory) .30-06 Springfield, Ruger No. 1-B, 26-inch Barrel 56.5 Speer 130-grain Hollow Point 3.06 3,004 12 .96 53.7 Nosler 150-grain Ballistic Tip 3.24 2,892 15 1.04 52.0 Hornady 168-grain Hollow Point 3.23 2,747 18 .98 BT 52.2 Sierra 180-grain Spitzer Soft 3.31 2,642 17 1.10 Point .300 Winchester Magnum, Weatherby Vanguard, 24-inch Barrel 70.0 Hornady 130-grain Soft Point 3.29 3,189 21 1.13 69.0 Sierra 150-grain Spitzer 3.34 3,018 17 1.12 67.0 Speer 165-grain Hot-Cor Soft 3.34 2,995 19 1.20 Point * Winchester cases and Winchester WLR Primers for all loads, except for the .300 Winchester Magnum, where Federal cases and Federal 215 magnum primers were used. ** Cartridge Overall Length.
My first real varmint rifle was a .220 Swift, so it'll always have a place in my heart. I mostly use 50- and 55-grain bullets in the Ruger M-77R, and the IMR 4007 SSC test rounds shot right in there with my standard loads. Accuracy was excellent for this gun at .76 inch with the 50-grain Speer softpoint over 41 1/2 grains, and velocity was a comfortable 3,802 fps. The Hornady 55-grain softpoint also did well with 40.4 grains at 3,785 fps. Of note are loads for two .22-caliber heavyweights. The Nosler Partition is represented by the tough 60-grain edition. With 39.2 grains, velocity was 3,523 fps, and it grouped under an inch. The equally efficient 63-grain Sierra Semi-Spitzer over 38.0 grains zipped along at 3,440 fps and grouped into .86 inch. This bullet packs a lot of weight for its length, and shoots well in about everything. This is about the longest bullet that will stabilize in the Swift's 1:14 twist.
For years I disparaged the .243 as too small for big game, too big for small game. Then I got one and found out what all the hoopla was about. It comfortably bridges the gap between the .22s and larger rounds and does a great job on deer and antelope. My Browning A-Bolt II took to IMR-4007 like 'coons to a corn patch. The load of 47.0 grains shown for the 55-grain Nosier Ballistic Tip is only a half-grain over the starting load, but recoil and noise are modest, accuracy is top drawer and the power level is plenty for coyotes. For a bit more speed and bullet weight, check out the 70-grain Speer hollowpoint over 45.0 grains (3,422 fps) or the 80-grain Sierra Spitzer boattail and 43.6 grains (3,220 fps). A representative deer bullet for the .243 is the slinky Hornady 105-grain A-Max. Propelled at 2,732 fps by 36.5 grains, it plunked into nice, sub-MOA groups.
It would be sacrilege to not include the '06 in any reloading article, so here it is. I was particularly impressed with the velocity and accuracy of IMR 4007 SSC test loads. The little Speer 130-grain hollowpoint with 56 1/2 grains blasted into .96-inch groups at 3,004 fps. A near-maximum charge of 52.0 grains boosted the Hornady 168-grain hollowpoint boattail to 2,747 fps, and it, too, shot under an inch. The 150- and 180-grain bullets also shot around an inch with 53.7 and 52.2 grains, respectively. All in all, a good fit for the powder.
.300 WINCHESTER MAGNUM
IMR 4007 SSC is admittedly a bit fast for the highest velocities with heavier bullets in the .300 Winchester Magnum, but it did darn well with each of the bullets tested. Note that all group averages were only slightly over an inch (about as good as it gets for this particular rifle). The load for the Speer 130-grain hollowpoint was intentionally throttled back to 70.0 grains. This made a mild, easy-shooting load. Velocities of the 150- and 165-grain hunting-weight bullets over 69.0 and 67.0 grains, respectively, were about 3,000 fps, and their ballistics were quite uniform.
I came late to the AR patty, but I'm trying to catch up. I now have several, and the latest addition turned out to be just the ticket for IMR 4007 SSC. Olympic Arms Co. offers its K8-MAG in .223, .243 and .25 WSSM calibers. The WSSMs are the epitome of "short and fat," and the compact powder column aids combustion and accuracy.
I recently obtained a K8 in .25 WSSM, and a comprehensive range of bullet weights was tested, from 75 to 120 grains, along with a couple of Winchester factory loads for comparison. In a nutshell, handloads with IMR 4007 SSC were tops in the accuracy department, had miseriy SDs and came close to the velocities of factory loads.
I should mention the one concession you must make when loading for an AR. The maximum cartridge overall lengths (COL) for the .223 and .243 WSSMs are 21/4 inches or less in deference to AR magazines.
Ammo for the .25 WSSM, however, measures 2.33 to 2.34 inches--which is too long. No worries, though. Just seat the bullet to a COL of 2 1/4 (or less) and everything's fine. Just remember to begin with the starting loads and work up carefully, as always. The COLs of all my test loads are shown in the table. COL for all of the .25 WSSM loads was 2 1/4 inches, except for the shorter 75- and 90-grain bullets, which were seated to the base of the case neck. With IMR 4007 SSC, there's plenty of room for both propellant and projectile. I had no feeding or ejection trouble with any of my test loads.
The .25 WSSM almost mimics the ballistics of the .25-06, which is no surprise since the WSSM's case capacity is almost as much as the .25-06. I have never used a .25 on varmints, but if I did, the 75-grain Hornady over 47 1/2 grains of IMR 4007 SSC would be my choice. At 3,229 fps, its power should make any 'chuck or coyote very nervous. A couple of other good varmint loads with taut-string trajectories are 45.6 grains under the 87-grain Sierra Spitzer (3,036 fps, .73-inch groups) or the 90-grain Sierra hollowpoint boattail at 3,043 fps (.97-inch groups).
The top loads with IMR 4007 SSC in the .25 WSSM would make terrific antelope and long-range deer rounds. Hundred-grain bullets rule the roost here, and a charge of 44.1 grains did great with the whole cadre tested. Velocities of this bunch hovered around 2,900 to 2,950 fps, and the largest group average was 1.04 inches. The all-copper Barnes 100-grain TS-X clocked 2,906 fps (this load may be of interest to folks in "no-lead" California).
A couple of new bonded bullets favored IMR 4007 SSC, too. A charge of 421/2 grains drove Nosler's 110-grain AccuBond at 2,825 fps and the Hornady InterBond of the same weight to an almost-identical 2,806 fps. Both masqueraded as match bullets.
But the .25s can use heavier bullets than the 6mms, and that to many is an advantage. A charge of 40.7 to 41.0 grains gives the Nosler 115-grain Ballistic Tip, Hornady 117-grain boattail softpoint or the Sierra 117-grain Spitzer boattail velocities right at 2,700 fps and all the accuracy required. The ancient but excellent Speer 120-grain Hot-Cor softpoint is a proven deer taker, and a charge of 40.4 grains gave it a velocity of 2,686 fps.
All in all, it was an eye-opening exercise. IMR 4007 SSC delivered fine accuracy, respectable velocities and uniform ballistics in a host of traditional favorites and the .25 WSSM as well.