The .17 Mach II A Collection of Hunt Reports By: Eric A. Mayer

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When the Hornady 17 Mach II came onto the scene back in 2004, I was hesitant to be excited about another rimfire round that was nothing more than a hyped-up .22 Long Rifle. Everyone knows by now that I am a diehard believer in the .17 HMR, so I was not part of the “too light a bullet” crowd. In fact, with my history of shooting the .17 Remington, I was quite aware of the destructive effects a small bullet, going very fast, could have on a small varmint. At the time, I was more interested in the 17 Aguila. With a heavier, less destructive bullet, the Aguila round seemed perfect for small game hunting. Unfortunately, the Aguila round was eclipsed by the 17 Mach II, only because of the extreme popularity of small varmint shooting. I say shooting, because there is really no concern about meat damage. In fact, you want the most destructive bullet possible, to exact a quick death.

After the initial release of the round, the 17 Mach II (17HM2) began to slowly gain popularity. Although many believed Ruger would chamber this round in their 10/22 action, it was soon realized that the difference in the pressure spike would not allow reliable performance without some changes to the design of the rifle. Ruger did not make the change so many hopeful semi-auto 17HM2 owners were left hanging. Thankfully, the aftermarket for the Ruger 10/22 was already very big. Therefore, it was only a matter of time before someone engineered a “fix” to the pressure spike issue. E.A. Brown & Co. came up with a heavier bolt to slow the action. That, coupled with a heavy barrel made by E.R. Shaw, made this kit a reliable alternative to a factory semi-auto. Volquartsen went as far as to design a new bolt to handle the round in their custom rifles. Both of these after-market options created a wave of new 17HM2 shooters, with well functioning and accurate rifles.

Currently, two factory rifles are available in the 17HM2 caliber. One is the Thompson R55, which was the original gun used to test the reliability of this caliber in a semi-auto rifle. It is well made and absolutely stunning. The other is the Marlin 717. The Marlin is another dependable rifle, but an inexpensive alternative with a price of less than $200.00 in most gun shops. Both are sure to expand even more the 17HM2 following.

Eventually, after reading the glowing reports of this round on Rimfire Central, I began to investigate the best option for me. Because of the type of hunting I do, I had originally planned on a light, semi-auto rifle. Unfortunately, I did not go with the proven E.A. Brown & Co. kit and ran into issues. This was quickly remedied by purchasing a CZ Model 452 American bolt action rifle, chambered in the 17HM2 caliber. I topped it with a small Weaver 2×7 rimfire scope, which kept the combo very light and easy to shoulder.

My first trip to the “range” gave me the opportunity to not only see what this rifle/caliber combo could do on paper, but where I sight-in also allows me many live targets in the form of ground squirrels within only a few yards of my set-up. To sight-in, I was shooting the Hornady and the CCI loadings of the 17HM2 ammunition. They both use the same bullet, a 17 grain Hornady V-Max with a listed velocity of 2100 fps. My CZ did very well right out of the box, with the following 5-shot groups at 50 yards:

As luck would have it, as soon as the sun began to warm up the brush piles behind my targets, the ground squirrels emerged. I took four ground squirrels at ranges from 40 yards to 168 yards (GPS used for exact measurements). All were one-shot kills, including the 168 yarder!

Here is a close-up of the first four. The 168 yard shot is on the far left. The blood you see is the entrance wound, no exit. The ground squirrel on the right, with the small hole, was hit in the chest as it looked down from a log. The bullet entered and did not exit. It was about 100 yards away.

By this time I was so excited about this caliber. The accuracy, virtually no kick and the mere fact that it was deadly on any ground squirrel sized game out to 175 yards made me a true believer, within the first 20 rounds!!

My first real chance to shake this cartridge out happened two months later during a ground squirrel shoot in Central California. I had just come back from a very successful shoot, using my CZ/17HM2 combo almost exclusively. This trip only confirmed what I had already knew about the devastation this caliber inflicted. If it sounds like I was becoming a “Kool-Aid” drinker about the 17HM2, well… just read this and see what you think:

When: 10/22/2005

Where: Central California

Weather: Hazy Sun, Mid/Low 80’s, Light wind

Firearms: CZ Model 452 American

Caliber: 17HM2 (17 Mach II) Rimfire


I’m writing this short report in the Rimfire Forum, only because the report and the hunt speak more of the caliber used, than the animals killed.

I headed up with my buddy, Tom, to a Central California Ground Squirrel spot where we met up with Bill D from the Go Go Varmint Board. We had just received permission to shoot a property that, up until now, had not been shot. Once we finally gained access, the morning had already slipped away with only a handful of shots fired. We setup our benches with a Walnut grove as a backstop, but as we realized earlier that morning, they were in the middle of harvesting the nuts so our shooting “lanes” were severely limited at times. The shooting was slow at first, with most shots being approximately 125 yards. The backstop was a berm that bordered the southern edge and was littered with holes. Bill and I were shooting CZ Model 452 American rifles chambered in the 17HM2 caliber. He was shooting CCI ammunition and I was shooting Hornady ammunition. Tom was shooting a Marlin lever action .22 Magnum using CCI HP ammunition.

The shots ranged anywhere from 50 yards out to the 125 yard berm. The hold-over on shots out to the berm was a couple of inches, but I zeroed 1″ high at 50 yards. The wind deflection was not too bad, so the hold was only an inch or so, depending on the breeze at the moment. I’m not going to compare the 17HM2’s ballistics to the .22LR in detail, within this report, as that has been beat to death in various forums on the internet. Instead, I am going to report on the kills made by this caliber and try to dispel some of the myths put out by folks who have probably never used the cartridge.

In the first location, the killing was pretty easy with the 17HM2. When the bullet connected, it made an audible “pop” and was followed with the classic “tail wave”. We had only a few run off, but those were normally the fault of bullet placement. Anything hit in the boiler, died on the spot.

At one point during the day, I walked up to speak to the guy running the harvesting operation at the Walnut grove next door. I borrowed Tom’s .22 caliber pellet rifle, hoping to kill some of the Ground Squirrels that had taken over the land-owner’s front yard. I came to find that he too was carrying a pellet rifle, shooting the Ground Squirrels that were crawling on or around the equipment they were using to shake the trees and collect the nuts. After a few minutes of talking to him, we had permission to shoot within the grove as well.

I headed back to our setup and shot for a bit until I realized that the harvesters had called it a day. Bill and Tom were shooting squirrels with the pellet rifle, so after a bit I headed into the grove with my CZ HM2. I skirted the trees as I entered the grove, seeing squirrels running everywhere. I dropped a couple right off, but looked down the grove and saw hundreds more. I walked down some more and sat down next to a tree using a bipod to balance my rifle. The shooting was pretty fast and furious. Most shots were within 75 yards, which is where I found the 17HM2 to perform flawlessly if I did my part. I dropped a total of 25 in a matter of minutes. One group of 12 died within feet of each other. I had a total of one squirrel run off and one other needing a follow-up shot (I had creased it’s spine with the first).

Below you will find links to pictures that show each of these 12. Because of the soft dirt, you can see for yourself how far the squirrels went before they died. Only two traveled anywhere and that was within a foot or so. These are not small ground squirrels, as the picture with the boot right below will show. That is a size 12 boot, next to an average sized ground squirrel:

After a little bit, Bill and Tom came up to join me and we shot a bunch. At the end of the day, Bill spent some time shooting in the grove and got in some pretty fast and furious shooting. When Bill finally came back, he had a huge grin on his face! He and his CZ 17HM2 cleaned up!

Final thoughts about the 17HM2 (17 Mach II):

Over a hundred 17HM2 Ground Squirrel kills later, I can speak as someone who is educated about the performance of this cartidge.

Everyday on the internet I read about how this caliber is “dead” or “dying”. These posts cannot be from people who have consistantly shot this cartridge. On the other hand, I read the glowing reports from folks like me who have shot the caliber and who are amazed by the accuracy and killing power it possesses. I’m sorry, but when it comes to killing small varmints, it blows the doors off the .22 Long Rifle. Ballistically, it is also a superior cartridge because it takes the guessing away on hold-over. Sight-in at 50 or 100 yards and the hold-over issue goes away. The 17 grain bullet is far more explosive than the standard 30 or 40 grain hp offered in the .22 Long Rifle.

Folks who have not tried the 17HM2 should and folks who bash the cartridge really don’t know what they are talking about.

Eric A. Mayer B)

Here are some kill shots showing very little, if any, “drag marks”:

That is only 6 of the twelve photos I offered on the original post. You can see the original post here:

“The 17 Mach II – Results from the Field, A Short Report”.

Of course with the approach of winter, I did not get a chance for any real hunts until just this last February – 2006. The results of that hunt turned me from a believer of the 17 Mach II, into a advocate of its versatility whenever I get the chance. As you will read below, Bill D. and I spent a day and a half using this round to kill approximately 400-500 ground squirrels. The ranges were 10 feet to Bill’s long shot at over 250 yards. Here is the hunt report:

Well folks, I have returned!! I betcha didn’t even know I was gone!

After hitting the SHOT Show in Vegas (SHOT Report coming later tonight), Bill D. and I headed over to my lease on Tejon Ranch for some predator calling and ground squirrel slaying. Needless to say, with the full moon and some other unknown factors, we called in absolutely nothing. That didn’t damper our spirits any, as we knew there were tons of ground squirrels to shoot. In fact, we ended up with 400-500 over a day and a half!! 99.9% of those were taken with the 17 Mach II!!

I’m going to post some pictures with some descriptionsand let the photos speak for themselves:

Here’s a dead squirrel taken with my CZ Model 452 American in 17HM2 caliber:

Here’s a cluster of squirrels taken with my CZ Model 452 American in a secret valley I know about. That 17HM2 really kills them dead. Even the large ones.

CZ & 17 Mach II, what a combo!!

Here’s a shot of Bill toasting some squirrels off a mountain side. In one spot, he kept killing them way up a hill making them roll and bounce most of the way down:

Last one of me with the small group from above. Lush is the only way I can describe the ranch right now. We saw tons of other game as well, like wild hogs, deer, waterfowl, etc. It was a great weekend!!

Thanks again to Bill D., he’s a killer shot with any rifle you put in his hands!!


Last weekend, my wife, daughter and I headed up to Tejon for a morning ground squirrel hunt. Up until now, Debbie has shot her customized Ruger 10/22 loaded up with CCI Velocitors. This time, I asked her to take my CZ 17HM2 and see how she liked it. Now Debbie likes to walk and take in the view while hunting. It isn’t about numbers, it is the experience that keeps her in the field. I did hear a few “cracks” that could not be mistaken for anything but the Mach II, so I knew something was dying. Sure enough, she came back with one that she shot. When asked, Debbie said that she had really enjoyed the rifle. “The ground squirrels died immediately”, she said as the limp, bloodied up body was plopped onto the log with the others I shot…

This morning I ordered 30 boxes of Hornady 17 Mach II ammunition for the coming weeks up at Tejon Ranch. I think another CZ in the Hornady 17 Mach II caliber is in our family’s near future…

By:  Eric Mayer

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