Thompson/Center R55 .17 Mach 2 Rifle

By Ed Timerson

T/C R55 Rifle
R55 All Weather. Illustration courtesy of Thompson/Center Arms.

In All my years of being a dedicated rifleman, I never had much interest in semi-autos, or the various .17 caliber centerfire rounds that came out over time. An autoloader could never match the accuracy of a good bolt action, or even some single shot rifles. When hunting, I prefer making my first shot count, instead of depending on quick follow-up shots. And who needed the very small .17, when .22 calibers had proven themselves on varmints for years?

Then came the push for .17 caliber rimfires, and again I thought, who needs it? But there was much widespread interest, and eventually the 17 HMR was introduced. It was an instant success. This round is based on the .22 Winchester Magnum necked down to .17 caliber. No sooner had this round been introduced, and a clamor started for a .17 caliber on the .22 long rifle case. Thus the 17 Mach 2 was born.

These rounds are not loaded with lead bullets like .22 rimfires, but with modern jacketed, carbonate-tipped spitzer varmint bullets at higher velocities than their .22 counterparts. This made them much more effective small game stoppers. Both rounds were also proving to be very accurate.

Ballistically, the HMR uses a 17- grain bullet at about 2550 fps, and the same bullet in the smaller Mach 2 is traveling around 2100 fps. There are also some brands of ammo loaded with hollow point bullets and different weights.

Recently, I've been doing a lot of testing with Thompson/Center arms, and did a tour of their Rochester, NH facilities. I met a lot of good people and found the company to be very upbeat.

One of their newer products is the R55 rifle. It is based on Thompson's .22 semi-auto action modified to shoot the 17 Mach 2 cartridges. Thompson claims one-half inch groups at 50 yards with this rifle, and in talks with their people, was told they shot 25 shot groups at 25 yards that could be covered with a quarter. This is great accuracy for any production rifle, and outstanding accuracy for a semi-auto rimfire! I decided I wanted to try one, and put in an order.

As of this writing, four models are offered: the Classic, with blued steel/walnut stock; All Weather, in SS, with synthetic stock; Benchmark, with heavy blued barrel and laminated wood; Sporter, with laminated wood. A nice feature is a trap door in the buttplate to store an extra magazine.

I ordered the stainless steel All Weather model with synthetic stock, and soon found I would have a wait, for demand was high. So when the rifle finally came in at my local gun shop, I think owner/gunsmith George Simmons was as excited as yours truly! You see, George has long been a fan of the .17 calibers.

Here are the basic specifications of the R55 All Weather rifle:

  • Caliber - .17 Mach 2
  • Action - Semi-automatic
  • Receiver - Stainless steel, drilled and tapped for scope base
  • Magazine - 5-round clip
  • Barrel - 20", match grade with target crown
  • Stock - Black composite with sling swivel studs
  • Safety - Manual operating thumb safety
  • Length of pull - 13 3/4"
  • Overall length - 37 1/2"
  • Weight - 5 1/2 pounds
  • Sights - Adjustable steel rear sight and ramp front with fiber optics

These rifles come with a match-grade heavy barrel 20 inches long that has a target style recessed crown. Tests have shown velocity peaks in this short barrel. Thompson makes their barrels, and I watched the process.

One point was really impressive. Finished barrels go through a long process of oven stress relieving. This is time-consuming, but shows Thompson's dedication to quality. The R55 is equipped with fiber optic sights and the barrel is solidly threaded into the receiver.

The synthetic stock reminds me of Weatherby rifles, for it has a raised, Monte Carlo style cheek piece, which I personally prefer. A flared pistol grip is comfortable to hold, and the forearm is wide, with finger grooves along its top edge. This fits nicely in the hand, and also works well on bench rests. The stock comes with sling swivel studs.

The action is narrow along its top half and gracefully tapered at the rear. It is drilled and tapped for scope mounts. There is a thumb operated safety on the right-rear side, and has a large magazine release button in the front of the trigger guard that is easy to operate. A 5-shot magazine came with this rifle and is formed from heavy cast steel. It is very solid and functioned without a flaw. The barrel is free-floated and the receiver solidly bolted to the stock with two through bolts. All in all, this is a well-made and designed rifle.

I had not received scope mounts yet, and was anxious to try this rifle out. I set up a twenty-five yard target on my range, and shot some three-shot groups with the factory fiber optic sights.

Two brands of ammunition were used. One was CCI, the other being Hornady. Both are loaded with 17-grain V-Max bullets. CCI is black tipped and Hornady is red tipped.

I am not used to open sights anymore, especially with now older eyes. But I found the bright fiber-optic factory sights easy to see and use, and managed to shoot several groups that measured between one-half to five-eighths of an inch. Great results shooting two different brands of ammunition with open sights!

About a week later the scope mounts were delivered. They are Thompson Maxima steel rings and split bases with black matte finish, which matched the synthetic stock. They are small and slim to fit this semi-auto, but very solid. I happened to have a Leupold compact M-8 4x scope not in use. It seemed a good size for this little rifle and was installed. My thoughts are effective range of these little 17 grain bullets is about 75 yards, and almost all of my shooting would be less. So more than four power should not be needed. The final touch was to mount a black web sling and swivels. The complete rig is very good looking.

Now it was time to take this rifle back to the range to see how it shoots with a scope. Again, CCI and Hornady brand ammo was used. I fired five-shot groups at 25 yards. The CCI measured .400 inches, and Hornady shot even better, measuring .220 inches. In all my years of shooting and hunting, I have never had a semi-auto rifle that would shoot with this kind of accuracy. I was truly impressed.

I thought it a good idea to try at least one more brand of ammo in my test rifle, so put in an order for some of Remington's new fodder. When it came in I found it also loaded with a 17 grain polycarbonate-tipped bullet, which is gold colored. Remington calls their version of the V-Max "Accutip-V" boat tails.

I wanted to shoot groups at 50 yards, and test all three brands of ammo to see how they stacked up. Shots were not single loaded into the chamber to prevent bullet point damage. All shots were fired semi-auto from the magazine. Groups are five shots. Remington and CCI shot about the same. Remington measured .820 inches, while CCI measured .815 inches. Again, Hornady proved the most accurate, with a .520-inch group. In this rifle, Hornady ammo came very close to Thompson's advertised accuracy.

As for this new R55 rifle, I have almost nothing but praise. When a person has been shooting and working on guns for as long as I have, one can usually find something to be critical of, and I had some small annoyances. The safety was stiff to operate and moved roughly. Being an enclosed action, the bore has to be cleaned from the muzzle. With a sharp-edged target crown, brushes and patches are hard to start in the bore. The trigger guard is small and can't be accessed with heavy winter gloves on.

But these are minor points. Over all, this rifle is a joy to shoot and hunt with, and proved very reliable. After several hundred rounds through it, there was one mal-function with Remington ammo. It failure to eject a fired round, leaving the case stuck in the bolt/ejection port.

I now have to change my way of thinking. There is a niche for this little .17, for it is proving more effective on small varmints than .22 rimfires, and can be used around the out-buildings of my small farm, for the bullets don't ricochet. I also have a semi-auto rifle that has proved worth owning. It is reliable, very accurate (which means everything to me), and even looks good. (Yes, this old dog is finally accepting stainless steel and synthetic stocks!) Thompson has long been known for single shot pistols and rifles. This semi-auto rifle, first in .22, and now .17 rimfire, is a fairly new market for them. I think they have a winner, and this rifle is a keeper.

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Copyright 2006 by Ed Timerson. All rights reserved.