.17 HMR and MACHII

[DaMadman]

Something I just read brought a thought to mind about the HMR and the MACHII that I didn't realize until now.

Could The .17 MACH II can be fired out of the HMR but not visa versa.

Aguilla is now offering the .17 in a necked down .22lr case. Technically the MACHII case is a stinger case which is a little longer than a standard .22lr I am wondering if the Aguilla is a STANDARD .22lr case or if it is a little longer like the stinger case?

[DaMadman]

Link to article (http://www.jesseshunting.com/articles/guns/category8/41.html)


Shooting the 17 Aguila in Rifles Chambered for the Hornady Mach 2

Andy Moe - JHO ProStaff - San Diego, CA
June 24, 2004

With the 17 Aguila’s introduction onto the market roughly coinciding with Hornady’s release of the specs for their 17 Mach Two cartridge, the question as to whether the shorter 17 Aguila cartridge could safely be fired in the Mach Two chamber has arisen many times. It came up so often in fact, that a trial was deemed necessary to study both the feasibility and safety of such a practice.


Ruger 10/22 and 77/22 barrelled for the M2
These rifles were used for the initial testing. It didn't take long to find that, not only did the Aguila ammo perform safely in the M2 chamber... it performed very well!
It was putting this issue to the test that had me on a plane to San Antonio, TX last week to meet with Aguila Engineer Efrain Peralta and Centurion Ordnance Logistics manager Mike Realme. I arrived in San Antonio on a balmy Thursday evening and testing began in earnest early Friday morning at Centurion’s in-house testing facility in the town of Helotes, TX.

Mike had arranged for a prototype Hornady Mach2 barrel to be shipped from Green Mountain Rifle Barrel Company earlier that week. The test gun was a stock Ruger 10/22 action mounted with a Simmons 4-16 A/O target scope. After fitting the fluted, stainless steel bull barrel, the whole unit was dropped into a Hogue over-molded stock. The range was prepared with suitable targets and an Oehler Model 66 chronograph set into place. With a brick of 17 Aguila at hand, the testing began under the watchful eye of Mr. Peralta. The weather was hot and humid.

I have been asked many times if I thought the 17 Aguila could be fired in the Mach2 chamber. The Mach2 is based on a CCI Stinger case (slightly longer than the standard 22LR ) necked down to 17 caliber to accept a 17 grain V-Max bullet. The 17 Aguila cartridge is based on a standard 22LR casing also necked down to 17 caliber, but having a longer 20 grain bullet. Both are loaded to the standard 22LR length. If you held the two rounds along side each other you’d see that the M-2’s shoulder is positioned farther from the rim than that of the 17 Aguila. This dimensional difference allows a 17 Aguila cartridge to fit into the M2 chamber, but not the reverse.
17 Aguila and 17 Hornady M2
Side by side, you can see the basic differences in the Aguila and the Mach 2. Note the higher shoulder on the M2 (on right).


How well would such an arrangement work? I have long theorized that the 17 Aguila cartridge would fire safely in the Mach2 chamber but the results would be ugly. The shoulder would be set forward, the velocity would be lowered dramatically, and accuracy would be non-existent. I have stuck by these views both publicly and privately since I first laid eyes on the Hornady prototype at the SHOT Show this year. I was about to proven wrong... mostly.

At Efrain’s direction, the firing began just to see if the rifle cycled and to examine the fired cases. Several cartridges were expended in this manner. All the casings were retrieved and examined individually. (We actually retrieved and examined all the spent casings from all the ammunition fired that first day.) The cases did blow forward at the shoulder, just as I’d expected. Of course, this was a logical prediction and no one expected otherwise. There were no splits. There were no case separations. The rifle was examined and found to still be in good, working order, so testing for accuracy began. This is when my theories began to fall apart.

Accuracy tests consisted of firing twenty consecutive five-shot groups at 25 meters. After a few rounds to sight in the scope, I began shooting for record. Even with this Ruger’s five-pound trigger I averaged .360 inches at 25 meters. My largest was about .7 and my smallest was .188 inches. This was amazing... absolutely on par with the accuracy I’d achieved with my custom 17 Aguila chambered rifles. When I saw the first 5-shot cluster drop into just over one-quarter inch I was amazed. I think we were all a little taken aback at the accuracy this rifle achieved. Engineer Peralta was quiet. Certainly he hadn’t expected this kind of accuracy from this the 17 Aguila cartridge fired in the longer Hornady chamber. Mr. Peralta asked that the testing be repeated the next day at a facility with a longer range to certify fifty-yard accuracy. We all agreed.

We would spend the remainder of that first day chronographing the Green Mountain barrel with the Hornady Mach2 chamber and one with a stock 17 Aguila chamber. An 18-inch Clerke barrel in 17 Aguila was chronographed to use for a base-line comparison. The Clerke 17 Aguila barrel delivered 1718fps with a standard deviation of 20fps. The Green Mountain M2 barrel delivered 1712fps with a standard deviation of 34fps. Only six feet per second difference. I had predicted low velocities but was again fooled by this amiable 17 Aguila cartridge. Needless to say, there was a lot of lively technical discussion at dinner that night.


Setting up
The author setting up to test at the San Antonio Target, Hunting, and Fishing Club.
The next day dawned hotter than the previous one and even more humid, if that was possible. We drove to the San Antonio Target, Hunting, and Fishing club located in N.W. San Antonio to begin the fifty yard accuracy tests. This would be the acid test for the Aguila people. Again, the results were astounding. At fifty yards, in a gentle cross wind, the average group size was .65 inches. The smallest was .37 inches and the largest was 1.06 inches. All targets were graced with a modicum of shooter error. Again, this was twenty consecutive five-shot groups with a stock Ruger trigger. At the end of the shooting I was sweaty, tired, sun burned, and elated that the accuracy we witnessed the previous day was no fluke. To prove it though, we needed another barrel.

Monday morning we placed a call to Rick Sanborn, at Green Mountain, to see if they could make up a barrel in 17 Hornady Mach2 for the 77/22 Ruger bolt action, and get it to us by Tuesday morning. Rick said he’d see what he could do. Shortly afterwards he called back and said he could do it. We had a 77/22 barrel chambered the next morning for the Hornady M2 cartridge. I was delighted to see that the barrel was of the 16.5 inch sporter configuration, identical to the barrel that graces my personal 17 Aguila rabbit rifle.

This 77/22 action was fitted with a super quality Hakko 4-16 x 56MM variable, adjustable objective scope. The arrangement of the large optic and the super trim barrel made it difficult to benchrest but the 25M groups were again, outstanding. The average was only slightly larger than those shot with the 10/22 Ruger. The performance of this second barrel was icing on the cake.

It was a rainy morning, but we were able to take advantage of a break in the rain to try the rifle at 50 yards. Unfortunately, the shooter was not up to the task on this outing. I couldn’t keep the called fliers out of the equation and I blew many an otherwise tight group. Still, the average was around .75 inches for 100 shots, which isn’t bad for shooting in the rain. I apologized for my poor shooting to Efrain but he just smiled, shrugged, and patted me on the back. I think he saw what he needed to see. I boarded a plane for San Diego that afternoon after bidding a heartfelt goodbye to Mike, Efrain, and Centurion Ordnance CEO, Carlos Romero. I surely hope to be able to visit them again soon.

My conclusions? The results speak for themselves. In barrels of good quality and chambered to factory specifications, the practice of shooting 17 Aguila ammo in the Hornady Mach2 chamber resulted in no safety problems, accuracy equal to that of ammunition fired in the standard 17 Aguila chamber, and velocity virtually identical to that of 17 Aguila ammunition fired in the Aguila chamber. With the exception of sooty cases with the shoulder moved forward, there is no difference in 17 Aguila performance. It may well be that when the M2 firearms are released the shooters who buy them will have added versatility in their cartridge selection. If a more game-friendly round is needed then the 17

[DaMadman]

now I wonder if the 17 MACHII will fire ok in the HMR barrels ?

[skeet]

The HMR round is based on the 22 mag case which is larger in diameter thant the 22 long rifle which the mach 2 is based on. The case will usually rupture. Be very careful is you try this...in fact don't try it. Won't blow up the gun but I can say it's dangerous :eek:

[Rocky Raab]

Skeet is correct. It is very dangerous to fire a .22LR in a .22 WMR barrel, and it would be equally foolhardy to attempt to fire a 17 Mach II in a 17 HMR barrel.

Both of the longer magnum-based catridges have a larger rim diameter and a larger case diameter. The shorter round will literally rattle in the magnum chamber. The smaller round almost always ruptures, either at the rim or down the length of the case - or both. Hot gas, burning powder and brass fragments exit the gun in most instances.

[Cossack]

Well I found one thing, you CAN sqfely fire the 17 HMR in a 22HMR..... although not very accurately. I put a new scope on my 22 WMR Striker, went to sight in and grabbed the 17's by mistake. They shot without a problem but in something more like a pattern....not a group. The cases did not rupture but were blow out to perfect 22 WMR size..... with a 17 stamp!
Based on that experience I'm not ready to conclude that you can't shoot a Mach 2 in a HMR or how accuracy will be affected. (Just read last night that you can safely shoot the 22 WRF in a 22 HMR).

[DaMadman]

Originally posted by Cossack
Well I found one thing, you CAN sqfely fire the 17 HMR in a 22HMR..... although not very accurately. I put a new scope on my 22 WMR Striker, went to sight in and grabbed the 17's by mistake. They shot without a problem but in something more like a pattern....not a group. The cases did not rupture but were blow out to perfect 22 WMR size..... with a 17 stamp!
Based on that experience I'm not ready to conclude that you can't shoot a Mach 2 in a HMR or how accuracy will be affected. (Just read last night that you can safely shoot the 22 WRF in a 22 HMR).

I didn't know that the .22 mag case was larger in diameter thant the .22 LR. I knew it was longer but did not know it was bigger around. In that case yes I would say it is probably prety unsafe.
It is nice to know that the .17 Aguilla will shoot ok in the .17 mach II for sake of more diverse ammo selection.

I also did not know there was any such round as the .22 HMR.

Shows how knowledgable I am