by B.B. Pelletier
Today, we’ll look at the velocity of the Tech Force TF99 Premier underlever air rifle. You’ll remember from Part 1 that I was impressed by the overall finish of this airgun. It’s one of the first Chinese spring guns that has a stock that’s made right. The small features such as the sights and the scope stop on the 11mm dovetail point to quality that wasn’t there on earlier models. The gun has definitely evolved.
I’m all for that, because — in the end — I just want a good airgun. Where it’s made makes no difference, as long as it’s accurate. I do want this large underlever rifle to succeed, and so far it’s looking good.
When you cock the rifle, the anti-beartrap device prevents the sliding compression chamber from moving forward again until the lever to release it is intentionally pulled. The lever is small and the spring tension needed to overcome it is heavy, so this is something you do consciously or not at all. It isn’t going to close accidentally. You’re not going to uncock this rifle without firing it.
Once the rifle is loaded and generally pointing toward the target, you pull back on the automatic safety to release it. Then, the rifle’s ready to fire.
The trigger is single-stage and releases with 5 lbs., 6 ozs. of pressure. It’s surprisingly free from creep, though the heavy release pressure keeps it from being a precision trigger.
The rifle has quite a bit of recoil and definite buzzing when fired. This changes with each type of pellet used, and those that fit loosely buzz the most.
First up is the Crosman Premier 7.9-grain pellet. Because the TF99 is a spring gun, it isn’t well-suited to heavier pellets, so we’ll stick with lead pellets in the 7 to 8.5-grain weight range.
The 7.9-grain Crosman Premier averaged 956 f.p.s. The spread went from 948 to 965 f.p.s. At that speed, the rifle produces 16.04 foot-pounds of energy at the muzzle.
Next, I tried the favorite lighteweight lead pellet — the RWS Hobby. Weighing just seven grains, this pellet has long been the standard for determining an air rifle’s velocity without endangering operation with non-lead pellets that can wear the bore or leave harmful deposits of plastic.
In the TF99, the Hobby pellet averaged 1022 f.p.s. The range of velocities went from a low of 1003 f.p.s. to a high of 1034 f.p.s. That works out to an average 16.24 foot-pounds of energy at the muzzle.
Finally, I tried some of the JSB 8.4-grain domes. These pellets fit the TF99 breech very loosely, and that showed in the velocity test. The average was 934 f.p.s., but the range was from 677 to 939 f.p.s. The two slow shots I got were no doubt due to pellet skirts not sealing the bore. The average muzzle energy was 16.28 foot-pounds.
I was able to measure the cocking force of the rifle at 33 lbs. It feels like it wants to be more than that, but the cocking lever goes back an unbelievable amount, thus reducing the effort to a manageable level. The gun also cocks incredibly smooth, as though it has been custom-tuned, which it hasn’t. That was a surprise, especially in light of the buzzy firing cycle.
The rifle is still dieseling on every shot. The detonations are becoming less frequent, and velocities are going to stabilize much closer than they are now once the oil burns off. I didn’t fire the rifle 100 times before velocity testing, so I’ll return and re-test velocity in Part 3, just to see if it’s starting to settle down.
Accuracy is next, and I have a suspicion that we’re in for a surprise.