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Hornady's Sweet Seventeen
Our Reloading/Rifles Editor says the .17 HMR cartridge is a real "hummer of a rimfire."
By Rick Jamison
Hornady has been quietly making progress toward the hottest commercial rimfire cartridge ever to come along. Shooting a .17-caliber bullet from a necked-down .22 Magnum case, it doesn't look very big and doesn't make a lot of noise, but it spits out a sleek little 17-grain bullet way faster than any rimfire going. And as Hornady gears up to make ammunition, Ruger and Marlin have announced bolt-action rifles to fire it.
So exactly what ballistics does the new round turn up? Hornady reports 2550 fps from a little 17-grain V-Max boattail bullet with a ballistic coefficient (B.C.) of .125.
How does that reporting stack up in the real world? I fired the ammo and found it more than lives up to Hornady's quoted figures. I chronographed 100 rounds from three different rifles--two Marlins and a Ruger--firing 10 10-shot strings over my Oehler system. The instrumental velocity (15 feet from the muzzle) average for all this shooting was 2573 fps, or 23 fps faster than the 2550 muzzle velocity advertised by Hornady. Nine of these groups were fired at 100 yards, and here the B.C. averaged .126, again, slightly better than what Hornady advertised. The B.C. average for 10 shots over 200 yards (one rifle) was .121, or slightly lower than Hornady's B.C. label.
With measured instrumental velocity and time of flight (to find B.C.), the Oehler system then computes muzzle velocity very accurately. The lower B.C. of .121 means that the actual muzzle velocity is 2610 fps, or 60 fps faster than Hornady's advertised figures. This is about 700 fps faster than a standard .22 Magnum rimfire with a standard 40-grain loading, and it is nearly as fast as the .22 Hornet centerfire with a factory 45-grain loading.
As for energy, a true muzzle velocity of 2610 fps with a 17-grain bullet turns up 257 ft-lbs. If you go with Hornady's advertised figures of 2550 fps and .125 B.C., the muzzle energy is 245 ft-lbs, or slightly less than a .22 Magnum.
Hornady calls the new rimfire the .17 HMR for Hornady Magnum Rimfire. With an abbreviated name like that, it's natural to call the HMR a real "hummer." It is.
I've been shooting prototype rifles and ammunition for the past few days on targets, expansion medium, and water-filled plastic bottles. The nifty little cartridge in the prototype rifles is one fun cartridge to shoot.
A LITTLE .17 RIMFIRE HISTORY
Development of the ammunition has been a long process. If you're a longtime reader of Shooting Times, you may already be experiencing deja-vu. If you've kept your back issues, take a look at the January 1992 issue for an article called the "Revolutionary .17 Rimfire." In that article I outlined experiments by Steve Chernicky, Terry Kopp, W.A. Eichelberger, A.J. Jones, Fred Wood, and others who have worked on various versions of small caliber rimfires. Shooting Times technical staff member Kopp's round was called the .17 KRM. It fired a 25-grain bullet at 2100 to 2400 fps that was intended to duplicate the performance of the defunct 5mm Remington Magnum. It did so nicely--and then some. Chernicky, on the other hand, went all out for velocity, pushing the limit and eventually getting 2700 fps with lighter 20-grain bullets.
Chernicky had so worked out things to the point that everything went smoothly. The actions had first-class rebarrelings, and the handloads were carefully assembled to .01 grain of powder. With velocity results like that a whole lot of people in the industry were excited about the prospects. I figured it was just a matter of finalizing R&D before we saw ammunition from a major company.
As it turned out, the major companies couldn't make ammunition that performed to market expectations at industry standard pressures. Industry standard pressure (to be read as "safe pressure") is the kicker, and being unable to make factory ammunition at industry standard pressure often happens with centerfire cartridge wildcats. A wildcat cartridge produces more velocity than it has any right to. The wildcatter touts the performance of his new round as producing more velocity than any factory offering of similar capacity and even has the chronograph data to prove it. The reality is that he abides by no industry standard pressure limit and has no means to measure pressure. He's added powder until there is sticky extraction or loose primer pockets and then backed off a bit. Some may even have measured case expansion, but the bottom line is the same. Pressures are overboard by industry standards. He has unknowingly exceeded the safe level and is operating in the margin of safety built into rifles and cartridge brass. He doesn't know how far he has intruded into this margin, and he won't know until something disastrous happens.
I'm not knocking wildcatting. I'm speaking in generalities and not about anyone or any specific instance in particular. Kopp and Chernicky are very experienced and know what they are doing. Both use handloading safeguards, and Chernicky had the added advantage of working with a manufacturer who supplied primed empty cases.
Only recently with Oehler's revolutionary Model 43PBL has the serious individual handloader had the means to get a relative measure on chamber pressure. For many years wildcatting handloaders did the best they could with the tools available. This is one reason why it's called "wildcatting." All this doesn't erase the fact that unless a person has a way to actually measure chamber pressure, he has no idea what it is.
In some respects, rimfire cartridges are even touchier to work with than centerfires. You should never try to pull bullets from rimfire ammunition. And you should never try to reform rimfire cases. It is dangerous. Remember, the priming compound is in the rim, a projection normally used to grip cases in bullet pulling and sizing. You could set a round off.
http://www.shootingtimes.com/ammunition/17_hmr_0508/
Our Reloading/Rifles Editor says the .17 HMR cartridge is a real "hummer of a rimfire."
By Rick Jamison
Hornady has been quietly making progress toward the hottest commercial rimfire cartridge ever to come along. Shooting a .17-caliber bullet from a necked-down .22 Magnum case, it doesn't look very big and doesn't make a lot of noise, but it spits out a sleek little 17-grain bullet way faster than any rimfire going. And as Hornady gears up to make ammunition, Ruger and Marlin have announced bolt-action rifles to fire it.
So exactly what ballistics does the new round turn up? Hornady reports 2550 fps from a little 17-grain V-Max boattail bullet with a ballistic coefficient (B.C.) of .125.
How does that reporting stack up in the real world? I fired the ammo and found it more than lives up to Hornady's quoted figures. I chronographed 100 rounds from three different rifles--two Marlins and a Ruger--firing 10 10-shot strings over my Oehler system. The instrumental velocity (15 feet from the muzzle) average for all this shooting was 2573 fps, or 23 fps faster than the 2550 muzzle velocity advertised by Hornady. Nine of these groups were fired at 100 yards, and here the B.C. averaged .126, again, slightly better than what Hornady advertised. The B.C. average for 10 shots over 200 yards (one rifle) was .121, or slightly lower than Hornady's B.C. label.
With measured instrumental velocity and time of flight (to find B.C.), the Oehler system then computes muzzle velocity very accurately. The lower B.C. of .121 means that the actual muzzle velocity is 2610 fps, or 60 fps faster than Hornady's advertised figures. This is about 700 fps faster than a standard .22 Magnum rimfire with a standard 40-grain loading, and it is nearly as fast as the .22 Hornet centerfire with a factory 45-grain loading.
As for energy, a true muzzle velocity of 2610 fps with a 17-grain bullet turns up 257 ft-lbs. If you go with Hornady's advertised figures of 2550 fps and .125 B.C., the muzzle energy is 245 ft-lbs, or slightly less than a .22 Magnum.
Hornady calls the new rimfire the .17 HMR for Hornady Magnum Rimfire. With an abbreviated name like that, it's natural to call the HMR a real "hummer." It is.
I've been shooting prototype rifles and ammunition for the past few days on targets, expansion medium, and water-filled plastic bottles. The nifty little cartridge in the prototype rifles is one fun cartridge to shoot.
A LITTLE .17 RIMFIRE HISTORY
Development of the ammunition has been a long process. If you're a longtime reader of Shooting Times, you may already be experiencing deja-vu. If you've kept your back issues, take a look at the January 1992 issue for an article called the "Revolutionary .17 Rimfire." In that article I outlined experiments by Steve Chernicky, Terry Kopp, W.A. Eichelberger, A.J. Jones, Fred Wood, and others who have worked on various versions of small caliber rimfires. Shooting Times technical staff member Kopp's round was called the .17 KRM. It fired a 25-grain bullet at 2100 to 2400 fps that was intended to duplicate the performance of the defunct 5mm Remington Magnum. It did so nicely--and then some. Chernicky, on the other hand, went all out for velocity, pushing the limit and eventually getting 2700 fps with lighter 20-grain bullets.
Chernicky had so worked out things to the point that everything went smoothly. The actions had first-class rebarrelings, and the handloads were carefully assembled to .01 grain of powder. With velocity results like that a whole lot of people in the industry were excited about the prospects. I figured it was just a matter of finalizing R&D before we saw ammunition from a major company.
As it turned out, the major companies couldn't make ammunition that performed to market expectations at industry standard pressures. Industry standard pressure (to be read as "safe pressure") is the kicker, and being unable to make factory ammunition at industry standard pressure often happens with centerfire cartridge wildcats. A wildcat cartridge produces more velocity than it has any right to. The wildcatter touts the performance of his new round as producing more velocity than any factory offering of similar capacity and even has the chronograph data to prove it. The reality is that he abides by no industry standard pressure limit and has no means to measure pressure. He's added powder until there is sticky extraction or loose primer pockets and then backed off a bit. Some may even have measured case expansion, but the bottom line is the same. Pressures are overboard by industry standards. He has unknowingly exceeded the safe level and is operating in the margin of safety built into rifles and cartridge brass. He doesn't know how far he has intruded into this margin, and he won't know until something disastrous happens.
I'm not knocking wildcatting. I'm speaking in generalities and not about anyone or any specific instance in particular. Kopp and Chernicky are very experienced and know what they are doing. Both use handloading safeguards, and Chernicky had the added advantage of working with a manufacturer who supplied primed empty cases.
Only recently with Oehler's revolutionary Model 43PBL has the serious individual handloader had the means to get a relative measure on chamber pressure. For many years wildcatting handloaders did the best they could with the tools available. This is one reason why it's called "wildcatting." All this doesn't erase the fact that unless a person has a way to actually measure chamber pressure, he has no idea what it is.
In some respects, rimfire cartridges are even touchier to work with than centerfires. You should never try to pull bullets from rimfire ammunition. And you should never try to reform rimfire cases. It is dangerous. Remember, the priming compound is in the rim, a projection normally used to grip cases in bullet pulling and sizing. You could set a round off.
http://www.shootingtimes.com/ammunition/17_hmr_0508/
