The .17 Win Super Mag (.17 WSM)
By Chuck Hawks
During the first week of January 2013, Winchester Ammunition sent me a press release about a most exciting new cartridge development, the .17 Win Super Mag (.17 WSM), which has been under development in the utmost secrecy for over three years. This is a rimfire cartridge that can launch a .17 caliber (.172" diameter), 20 grain bullet at the unheard of muzzle velocity (MV) of 3000 fps, making the .17 WSM the fastest rimfire cartridge ever developed. In fact, its velocity is solidly in the realm of high velocity centerfire cartridges. In a sense, Winchester's new .17 Super Mag completes the range of .17 caliber varmint cartridges that began (commercially) in 1971 with the .17 Remington.
The .17 Remington was the first standardized .17 cartridge and its velocity and general ballistic performance essentially duplicated the over 4000 fps MV of the .220 Swift, the long time velocity champion among American .22 caliber cartridges. However, although rifles and ammunition are still available, the .17 Remington never really caught on with the general shooting public. A few dedicated varmint shooters tried the .17 Remington and liked it, but most probably could not see much advantage in an "oddball" caliber that duplicated the .220 Swift, already established for decades prior to the introduction of the .17 Remington. The fact that the .17 Remington burned less powder and created less noise and recoil than the .220 escaped the notice of most shooters, who never tried the cartridge.
There matters stood, with the .17 being a specialty caliber barely recognized by most shooters, until the introduction of the .17 HMR in 2002. The rimfire .17 HMR is based on a necked-down .22 Magnum case loaded with a 17 grain bullet and it achieves a MV of 2550 fps. It offers near .22 Hornet centerfire ballistics to rimfire shooters at a considerably lower price and without the hassle of reloading. It is a brilliantly accurate and effective varmint cartridge with a maximum point blank range (+/- 1.5") of about 165 yards. For the first time, a rimfire cartridge was treading on the ballistic heels of a centerfire varmint cartridge. Shooters embraced the .17 HMR concept in great numbers and, finally, a .17 caliber cartridge became a best seller. This did not escape the notice of the major ammunition manufacturers.
In late 2007, Remington introduced their .17 Remington Fireball, based on a necked-down .221 Fireball case and in 2012, Hornady doubled down on their success with the .17 HMR by introducing the .17 Hornet, a centerfire .17 based on a blown out and necked-down .22 Hornet case. In factory loaded form, these two .17's offer ballistic performance at what is essentially .22-250 levels. The little .17 Hornet launches a 20 grain bullet at 3650 fps and the .17 Rem. Fireball launches a 25 grain bullet at 3850 fps. We now had .17 caliber varmint cartridges that could be compared to the .22 Hornet, .22-250 and .220 Swift; three of the four major velocity niches occupied by established centerfire .22 varmint cartridges. However, this left one glaring hole in the .17 caliber line-up, a medium range cartridge between the rimfire .17 HMR and the centerfire .17 Hornet, with MV in the .221/.222/.223 range of 2995-3240 fps.
With the advent of the .17 WSM we have such a cartridge. Rimfire cartridges are much less expensive to manufacture (and therefore to sell to consumers) than centerfire cartridges. While most centerfire rifle cartridges are sold in boxes of 20, rimfire cartridges typically come in boxes of 50. 50 rounds of rimfire ammo typically cost much less than 20 rounds of centerfire ammo. Rimfire ammo eliminates the economic necessity for reloading, which many high volume shooters find a tedious and time consuming chore. The .17 Win Super Mag is a win/win proposition on the performance and price fronts.
The .17 WSM case is considerably larger than that of the .17 HMR or .22 WMR and holds more powder. Winchester (Olin) used their .27" industrial blank case designed to drive concrete nails as the basis of the .17 WSM cartridge. Reinforced with a stronger case head and body to operate at higher pressure (33,000 psi), necked-down to accept .172 caliber bullets and given a sharp shoulder, the .17 WSM was born.
Winchester is initially producing three loads for the .17 Super Mag. These include an Elite Varmint HV (high velocity) load using a 20 grain Plastic Tip bullet at a MV of 3000 fps (#S17W20), a Super-X load with a 20 grain JHP bullet at the same MV (#X17W20) and an Elite Varmint HE (high energy) load with a 25 grain Plastic Tip bullet at a MV of 2600 fps (#S17W25). These loads are available in 50 round boxes or 1000 round cases.
The .17 WSM easily outperforms all previous rimfire varmint cartridges, particularly the .17 HMR and .22 WMR, in both wind drift and trajectory. It delivers the accuracy and flat trajectory necessary for reliably hitting rodents at ranges beyond 200 yards. It claims 150% of the .17 HMR's downrange energy to ensure humane, one shot kills.
The 20 and 25 grain plastic tipped projectiles used in the Winchester Elite HV and Elite HE loads are Hornady V-Max bullets. The 20 grain V-Max has a sectional density of .097 and a ballistic coefficient of .185. Here is the Maximum Point Blank Range (+/- 1.5") trajectory for the 20 grain V-Max at 3000 fps MV, calculated for a 1.5" sight height using standard conditions (range / bullet path / velocity / energy):
Muzzle / -1.5" / 3000 fps / 400 ft. lbs.
The MPBR of that load is 207 yards (+/- 1.5"). Put your scope's crosshair at the top of a standing, medium size varmint's head at 225 yards and the bullet should go through his chest at 225 yards. For comparison, the centerfire .222 Remington factory load with a 50 grain PSP bullet (BC .175) at a MV of 3140 fps has a MPBR of 212 yards. All of this is a long way of saying that, ballistically, the .17 Win. Super Mag is the rimfire equivalent of a medium range .22 centerfire varmint cartridge.
Copyright 2013, 2014 by Chuck Hawks. All rights reserved.