There are two relatively new .17 caliber rimfire loads. Both offer improved performance over all previous rimfire varmint cartridges. One is the CCI A17 load, introduced in 2015 for the well established .17 HMR cartridge and the other is the fastest rimfire ever, the .17 Winchester Super Mag (WSM), introduced in 2013.

The A17 is a stepped-up .17 HMR load, while the .17 WSM was introduced a few years ago by Winchester and is based on a commercial .270 nail gun cartridge case. There is no question that the larger case capacity of the .17 WSM gives it a performance advantage over any .17 HMR load, but the A17 reduces the gap. The point of this comparison is not to determine a performance "winner," but to see how close the A17 comes to the reigning king of rimfire cartridges.

A17 .17 HMR

Designed for use in the Savage A-17 autoloading .17 HMR rifle, CCI's A17 ammo (# 949CC) is intended to achieve increased reliability in .17 HMR autoloaders in general (which has previously been a problem) and the Savage A-17 rifle in particular. Guns and Shooting Online has previously reviewed both the Savage A17 rifle and the CCI A17 ammunition.

We found that the A17 load, as advertised, offers at least a 100 fps advantage over previous .17 HMR offerings with 17 grain bullets. Furthermore, it is generally just as accurate as other .17 HMR loads in manually operated (bolt and lever action) .17 HMR rifles. Thus, A17 ammo offers a performance increase for all .17 HMR shooters.

A17 ammo has been adopted by most of the Guns and Shooting Online staff as their preferred ammo for their bolt action .17 HMR varmint rifles. It carries an August 2016 retail price of $14.99 for a box of 50 cartridges from MidwayUSA ($0.30 per cartridge). A17 ammo is generally available both locally and from online sources at this time.

.17 WSM

Winchester introduced the .17 WSM cartridge right into the teeth of the Obama Administration inspired ammunition shortage. However, Winchester has managed to produce enough .17 WSM ammo to keep it on most store shelves. Since the cartridge's introduction, Federal American Eagle brand and Hornady have also introduced .17 WSM loads that are widely distributed.

Winchester offers loads with 20 grain (the HV load) and 25 grain (the HE load) bullets in their Elite ammunition line, while American Eagle and Hornady ammo is loaded only with 20 grain bullets, as of this writing. The advertised ballistics of all three 20 grain offerings are identical and all three use essentially identical, plastic tipped, spitzer bullets.

Since the 20 grain bullet is the most popular offering in .17 WSM, that is the load we will use for this comparison and since Hornady is the latest player in the .17 WSM game, we will use their 20 grain V-Max bullet load for this review (# 83180). It carries an August 2016 retail price of $16.49 for a box of 50 cartridges from MidwayUSA ($0.33 per cartridge). Like A17 ammo, .17 WSM is generally available as this is written.

The Comparison

We will compare the CCI A17 .17 HMR and Hornady .17 WSM loads in velocity, energy, trajectory and bullet sectional density (SD) using the factory specifications where possible. Unlike our chronograph velocity testing, these are referenced to standardized conditions. Note that the A17 uses a 17 grain tipped bullet, while the .17 WSM uses a 20 grain V-Max tipped bullet.

Velocity

Our independent chronograph testing has found the factory specs to be conservative, so you are likely to get at least the quoted velocity from your rifle. Higher velocity increases energy and flattens trajectory. Velocity is listed in feet per second (fps) from the muzzle (MV) to 200 yards.

• CCI A17 .17 HMR: 2650 fps MV, 2312 fps at 50 yards, 2000 fps at 100 yards, 1723 fps at 150 yards, 1475 fps at 200 yards
• Hornady .17 WSM: 3000 fps MV, 2745 fps at 50 yards, 2504 fps at 100 yards, 2275 fps at 150 yards, 2058 fps at 200 yards

Energy

Kinetic energy is a good measure of killing power when comparing similar loads and bullets. Experience has shown that both the .17 HMR and .17 WSM cartridges are capable varmint killers within their maximum point blank range. Obviously, the more energy on target, the more damage that can potentially be done. Energy is listed in foot-pounds (ft. lbs.) from the muzzle (ME) to 200 yards.

• CCI A17 .17 HMR: 265 ft. lbs. ME, 202 ft. lbs. at 50 yards, 151 ft. lbs. at 100 yards, 112 ft. lbs. at 150 yards, 82 ft. lbs. at 200 yards
• Hornady .17 WSM: 400 ft. lbs. ME, 335 ft. lbs. at 50 yards, 278 ft. lbs. at 100 yards, 230 ft. lbs. at 150 yards, 188 ft. lbs. at 200 yards

Trajectory

The flatter the trajectory, the easier it is to hit downrange. This is especially true when the targets are small, as are varmints. The following trajectory figures are computed for a sight height 1.5" over the bore (typical for scoped rifles) and are based on a 100 yard zero, which is used for the trajectory figures published by both manufacturers.

• CCI A17 .17 HMR: +0.1" at 50 yards, +/- 0" at 100 yards, -2.3 at 150 yards, -7.5 at 200 yards
• Hornady .17 WSM: -0.2" at 50 yards, +/- 0" at 100 yards, -1.2" at 150 yards, -4.1" at 200 yards

Instead of zeroing at 100 yards, sight both cartridges to hit 1.5" high at 100 yards and the Maximum Point Blank Range (+/- 1.5") of the A17 load is about 172 yards, while the MPBR of the .17 WSM is 205 yards. This allows you to hold dead-on most varmints without needing to make any compensation for trajectory out to the MPBR distance.

Sectional Density

The heavier a bullet is for its caliber, the higher its sectional density will be. Both the .17 HMR and the .17 WSM use bullets of .172" diameter. In big game calibers, sectional density is an important factor in bullet penetration. However, SD is less important in varmint calibers, because varmint bullets are designed to disintegrate on impact, rather than for deep penetration.

• CCI A17, 17 grain bullet: .084 SD
• .17 WSM, 20 grain bullet: .097 SD

Summary and Conclusion

From the beginning, it was a forgone conclusion that the .17 WSM would outperform the A17 .17 HMR in a ballistic comparison. However, both loads, as well as the regular .17 HMR load (a 17 grain V-Max bullet at 2550 fps MV), are proven varmint killers to at least their maximum point blank ranges. Both loads are also very accurate, while recoil and muzzle blast are minimal.

According to my calculations, the A17 load has a MPBR of 172 yards, compared to the 165 yard MPBR of the regular 17 grain, .17 HMR load. The 20 grain .17 WSM load has a 205 yard MPBR, or about a 33 yard advantage over the A17 load and a 40 yard advantage over the regular .17 HMR load.

Ammunition is readily available in both .17 HMR and .17 WSM. The CCI A17 load is available locally and from online retailers, as is a variety of .17 WSM ammo. Based on comparing MidwayUSA's retail prices, the premium for the higher performance .17 WSM is only three cents per cartridge, or $3 more for 100 rounds. Most varmint hunters can probably afford this and there is no denying the .17 WSM's ballistic advantage across the board, particularly if the largest varmints and small predators (coyotes and foxes) are on the menu.

The .17 HMR's big advantage over the .17 WSM is in the availability of rifles. As of 2016, to the best of my knowledge, the only commercially produced .17 WSM hunting rifles are the laminated hardwood or composite stocked Volquartsen autoloader (based on a Ruger 10/22 type action), the synthetic or laminated hardwood stocked Savage B-MAG bolt action and the walnut stocked Ruger M77/17 bolt action.

Of these, the Savage is the most economical, the Volquartsen is the most expensive and the Ruger is probably more appealing to most shooters. There are also a couple of "tactical" or AR-15 style autoloaders on the market from Franklin Armory and Jard, Inc.

On the other hand, .17 HMR rifles are available from practically everyone who manufacturers rimfire rifles and in a variety of grades and actions, including autoloading (the Savage A17), turn bolt action, straight pull bolt action (Browning), lever action and single shot. Price and quality varies from a Meister Grade Anschutz to a Stevens single shot. The .17 HMR has a big advantage over the .17 WSM in terms of rifle selection.