TAU-200 Match Rifle

 

By Todd Cooper

 

 

The .177 caliber BRNO TAU-200 is a great entry level 10 meter style CO2 target rifle. With the iron sights removed and a scope mounted it makes an accurate mini-sniper rifle for close distance plinking at small targets. Veeery nice!

 

A short time ago I bought a "used" TAU-200 CO2 rifle just because the deal was good and it seemed like something I might want to tinker with for a while. I had no real need for the rifle so I tinkered, tested, evaluated, and sent it onwards.

 

A complete disassembly was the first thing that had to be done to the TAU rifle. The gun was sitting unused for over a year and I wanted to give it a thorough cleaning, inspection, and lubing. Okay... I wanted to see what made it work.

 

The TAU-200 rifle has a few similarities to the TAU-7 pistol. Both guns use the same powerlet piecer caps, bulk adapter end cap, bulk fill transfer bottle, valve stem and valve seal. The all metal construction and wooden stocks on the TAUs are nice features to see in these days of synthetic everything.

 

My rifle was the adult version but a junior version, with a shorter stock, is also available. The stock on the adult rifle has a short pull length of 13.5" but this can be adjusted to 14.0" with the two spacers installed. When a scope is mounted, the two comb spacers can be removed for a preferred lower comb height. The spacers can then be used to increase the pull length by another 1/2". I seem to like the 14" length for my own build.

 

The TAU-200 has a deeply recessed muzzle. The actual crown on my example was 6 7/8" from the end of the 23 ¼” barrel. The actual rifled section of the barrel would only be 16 3/8" long. From the outside of the barrel you can't tell it's recessed until you look at the huge 1/2" hole in the end. This recessed muzzle works well to dampen the sharp CO2 report. A low sounding “thunk” is about all that is heard when shooting. Reduced lock time is usually the reason for the shorter rifled section and the use of a longer barrel, with recessed crown, allows a long sight radius to be maintained with a short rifled barrel.

 

 

 

SPECIFICATIONS

 

 

Features

 The beech stock is adjustable for comb height and pull length by using the four spacers provided. The butt plate on the TAU rifle is adjustable for vertical position.

 The metal front sight is mounted on an 8.75" long removable sleeve which functions as a muzzle weight. This heavy one-piece sleeve could be cut into 3 sections with setscrews installed for securing each section. This would allow weight to be varied.

 The rear target sight is made of both metal and tough synthetic material. The adjustment parts and knobs of the sight are all metal.

 The TAU-200 comes with 3 metal rear aperture inserts and several front sight insert sizes.

 Dry firing is a simple task with this rifle. A short bolt movement of about 1/2" cocks the trigger for this feature. A complete bolt movement allows for firing a pellet but a cocked rifle can also be de-cocked by using the dry fire feature.

 The all-metal receiver on the TAU-200 is a bolt-action style. Grooves run along the top surface of the receiver and allow the mounting of optics or the target sight provided.

 Disassembly of the TAU-200 is a simple task. The trigger mechanism is fastened to one of the side plates so things don't fall apart when the other plate is removed. This gun seems user friendly and home maintenance is possible with no specialised tools needed.

 The rifle comes with piercer caps for using powerlets and also a bulk-fill end cap and a small 150 gram transfer bottle for using bulk CO2.

 Variable velocity, with a maximum of around 560 fps with moderate weight pellets.

 

 

 

VELOCITY/ACCURACY TESTS

 

The following velocity and accuracy tests were recorded at 64F degrees using the unaltered TAU-200 rifle. The rifle was clamped into a Black & Decker Workmate for stability and consistent alignment with the chronograph. Velocity is variable on this air rifle but I chose to set the adjustment screw flush with the receiver tube for this section of testing. Different velocity choices may produce different accuracy results.

 

Factory Hammer Spring

 

 

 

Note: The JSB Exact pellet used in all the TAU-200 testing was the small 4.50mm. That was the only version I had at the time. The JSB Match was 4.49mm.

 

The next experiment involved replacing the factory hammer spring with a shortened 16# Colt 1911 recoil spring. I used about 1/2 the spring and bent the ends flat to allow it too sit better inside the receiver. The new spring was slightly less in diameter and was cut about 2 coils longer than the factory TAU hammer spring.

 

The large screw that holds the hammer spring in the rifle also allows pre-load tension to be adjusted. About 10 turns of the screw are possible. An odd thing about the adjustment screw was it had no effect on velocity when the 1911 hammer spring was installed. I tried turning the screw inwards and outwards throughout the 10 turns with no effect on velocity. Maybe the 1911 recoil spring is consistent throughout compression while the factory TAU spring varies in tension. This is only my guess.

 

Velocity and accuracy results were recorded at an ambient temperature of 63F. Once again, the workmate was used to secure the rifle during the test.

 

Custom Hammer Spring

 

 

 

Note: The Crosman Premier Heavy (10.5gr) pellet was not tested for accuracy because my supply was very limited.

 

Accuracy with the heavier hammer spring was very close to the accuracy with the factory hammer spring. The JSB Match seemed to have a strong preference for the lower velocity but the other pellet types did not seem to have a preference.

 

Long Distance Accuracy

I didn’t spend too much time checking long distance accuracy with the TAU-200. Tin can plinking occupied most of my outdoor shooting time whenever I took this rifle out for an afternoon.

 

The TAU was tested for accuracy at 30 yards from a benchrest, using the heavier 1911 hammer spring and 7.9 grain Crosman Premier pellets. With a slight breeze I managed .70", .75", .75", .80" for 5 shot groups. On a calm day the groups should shrink to maybe .60” ctc at 30 yards.

 

Velocity Change vs Temperature Change

My final test involved slightly increasing ambient temperature and checking the velocity results when using the two hammer springs. The following results were recorded at a temperature of 70F degrees when using the 1911 hammer spring.

 

 

Tests were completed and charted, using the same pellets at the low 60s temperature and then again at a temperature which was 8F degrees warmer. With the factory hammer spring the velocity increased an average of 4 fps at the higher temperature. With the 1911 hammer spring the velocity increased an average of 18 fps at the higher temperature. It would be interesting to check velocities at temperatures in the high 70s or 80s but I had no method of doing the test at the time I had the rifle.

 

At the 70F temperature the velocity adjuster still had no effect on velocity output with the heavier aftermarket spring. With the factory hammer spring the adjuster did affect velocity.

 

Originally I was hoping for 600-625fps with 7.9 grain Crosman Premiers and I think outdoor temps of 75-80F would bring those numbers.

 

Minor Problem Encountered

A slight problem was encountered when using the heavier 16# Colt 1911 replacement hammer spring. After several hundred pellets the added spring tension caused the hammer rod linkage to bend in a bow shape towards the trigger. This is a typical problem encountered because of the light metal used on the factory rod. Some tinkerers shape a new stronger rod from a short length of heavier spring wire. I found a length of spring wire with a thickness of .107" and shaped it using two pair of needle-nose plyers. The new rod fit and worked fine after a bit of thinning at the end that inserts into the hammer. It's not an extremely difficult task to bend a new linkage and the new rod will not bend.

 

In the end I straightened and re-installed the factory hammer rod along with the factory hammer spring and all is working 100% again. I will likely keep the factory spring installed since most of my shooting is at 10 meters and with factory parts I get over 100 shots from a bulk fill. Two bulk fills were tested with the heavier parts and results were 48 and 54 shots per fill.

 

 

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