Tech Force TF79 Competition Rifle – Part 2
by B.B. Pelletier
Today, we’ll look at the trigger of the .177 caliber Tech Force TF79 Competition Rifle, which I promised would get a report all its own. Back before the QB 78/79 rifles came to market and back when I was still reporting on the original Crosman 160s, I discovered that there were different variations of the model that came with different triggers. The first 160 made back in the 1950s had a dirt-simple, direct-release, sear-type trigger that had no special advantages. This was the rifle that had a crossbolt safety through the stock. Back then and probably still today, those rifles commanded less money than the later models that have the trigger I’m going to discuss today.
In fact, this trigger I’m discussing today was the cover subject of the premiere issue of my newsletter, The Airgun Letter, published in March 1994. So, for those folks who wonder if I’ve ever looked at the TF79 before now: I have been looking intently at both it and its direct ancestor for the past 17 years, which is my entire airgun writing career.
The first article in the first issue of The Airgun Letter was about the adjustable trigger in a Crosman 160.
Back in 1994, I was just learning how to take pictures with a 35mm film camera, and it would be more than a year before I started having much success. When it came to capturing the inside of the trigger, I didn’t photograph it, I drew it! It took about four hours to complete the drawing, but I’ve used it many times since.
Before I could take good pictures, I drew things to illustrate them. This is my drawing of the 160 adjustable trigger. The only difference between this trigger and the one we’re reviewing today are two tiny coiled springs that put side tension on the two trigger-adjustment screws. Today, things are simpler and better.
At the time, I was aware that the 160 trigger was based on a crossbow trigger from the Middle Ages. In The Crossbow by Sir Ralph Payne-Gallwey, a reference book I’ve recommended several times, you can see the cross-section of a crossbow trigger and apply it directly to the 160 trigger design.
From Sir Ralph Payne-Gallwey’s historic book, The Crossbow, this sectional drawing of a crossbow trigger shows the similarity to the 160 trigger. Gallwey refers to the sear as the revolving nut.
You can see how the crossbow trigger was able to restrain hundreds of pounds of force, yet break with relative ease. Well, the 160 hammer spring is not nearly as powerful as a crossbow; so, with adjustment, it can be made very fine. And, the adjustments are what differentiate this trigger from the primitive crossbow trigger.
From the factory
The trigger-pull right out of the box measured between 1 lb., 8 oz. and 1 lb., 10 oz. It’s a two-stage unit with stage one being extremely light and stage two rather long and very creepy, if also light. I can fix most of that with lubrication and adjustments.
Removing the TF79 action from the stock requires the removal of one large nut in the bottom of the forearm that requires a large spanner. Then, the safety must be removed. Just rotate the lever down while pushing on the back side of the safety pin, and you’ll feel it give when it’s aligned for disassembly. I used a pin punch to drift it out, not because it fits tightly but because the cam it bears against, which is the actual part that blocks the trigger, is under a lot of spring pressure. You can see that spring in my drawing or in the second photo below.
Out of the stock, the TF79 trigger is a unit contained inside a metal box. Remove the two Phillips screws to take off the plate for adjustments. The hole allows for inspection of the sear contact without removal of the sideplate.
With the sideplate removed, you can see how the trigger works. The sear engagement adjustment (top left) has a locking nut, which is an improvement over the 160 trigger.
I found this trigger to be much better built than the old Crosman 160 trigger. With that one, you had to worry about the parts jumping out of the trigger box when you tested the adjustments, but this current one holds together and allows all the testing you want. As a result, I was able to get a fine trigger release in a matter of a few minutes. It’s no lighter than before, but nearly all the creep is gone. I could have removed all of it, but the amount of sear engagement when I did so seemed too small for safety. So, there’s one very repeatable bit of slippage in stage two and then the let-off is crisp. Now, the trigger stops immediately after release. The feeling is one of precision, and I found it much easier to achieve than with a genuine Crosman 160 trigger.
I also lubed both the sear and the trigger catch with moly. Hopefully, this will bond with the metal surfaces and improve the smoothness of the pull over time.
Assemble the rifle
Putting the trigger plate back on is no chore at all, because the three pins that use the plate as their other bearings remain in alignment with the plate off. In the 160, you had a heck of a time with some guns, because these pins would tilt from the spring tension they were under. Putting the trigger plate back on a 160 was a lot like picking a lock. That’s no longer the case.
The next step is to drop the action back into the stock and tighten the spanner nut. After that, the safety goes back, and there’s a trick to it. From the opposite side of the safety hole (the left side of the gun), push the safety cam up with a thin-bladed screwdriver to allow the safety lever to be inserted in the right side of the hole. Once it’s in, it’ll hold the cam out of the way and easily go in the rest of the way. The rifle is now assembled. Taking the safety out or putting it back in is a 15-second drill once you have the knack.
Guys, this is a hundred-dollar trigger when it’s properly adjusted. It’s not quite a Rekord, but it’s in the Walther LG 55 class for sure.