Career Infinity by Shin Sung - Part 3
by B.B. Pelletier
Let's look at the Career Infinity velocity. The new inlet seal I showed you yesterday is working fine, and it may turn out to be the fix for this problem. I'll let you know at the end of the accuracy report, when the gun has been filled many more times.
You may recall that this gun doesn't shoot the pellets from the cylinders. It pushes them into the breech with a bolt probe, and that's where they are fired from. That way the long gap from cylinder to breech is a non-issue, as far as accuracy goes. The pellet begins its flight while already in contact with the rifling.
However, there are two observations I will make about the cylinders. First, they do not rotate far enough to align with the bore during the cocking stroke. After cocking, I had to advance the cylinder another half turn to get the pellet chamber aligned with the bore. You know that because the bolt probe won't align with the chamber in the cylinder, which prevents the sidelever from closing. That held true for both cylinders that came with the gun, and it takes away some of the speed you get from the rifle being a repeater.
The second thing I noticed about the cylinders is that it's possible to insert them into the receiver backwards, with the tails of the pellet pointed forward. If you do that, the pellets still feed into the barrel and still fire normally. Remember to load the cylinders with the outer spring to the rear.
Cocking is easy enough. It isn't exactly smooth, but the sidelever allows a powerful hammer spring to be compressed with reasonable effort.
The safety is, thankfully, manual. It's always there if you need it, but you don't have to fumble with it if you don't want to. It's easy enough to put on and take off with just the trigger finger.
The onboard pressure gauge reads in bar instead of psi. I found the one on the test gun reads about 25 bar low, so 3,000 psi reads as 175 bar instead of 206.
There's a power adjuster on this rifle. There are four spots on the power wheel located in front of the triggerguard and there are a total of 12 positive click detents from lowest to highest power. Since that presents a lifetime of possibilities, I decided to limit the settings based on the pellet being used and how the air was holding out. With heavyweight Eun Jin pellets, I used the highest setting; with medium-weight Crosman Premiers and Air Arms pellets, I used the lowest setting.
The Eun Jin pellet weighs 28.4 grains, nominally. With a fresh 3,000 psi fill, I got the following results with the first six shots:
That tells me the rifle is not on the power curve at 3,000 psi. It could also be that the valve cannot function with pellets this heavy. I then filled it to 3,300 psi and got these results:
It seems as if the gun's maximum fill is still higher than 3,300 psi, but I don't have the pressure to go there. Nor do I think I would if I could. I've seen the walls of the reservoir, and they aren't that thick. I don't recommend overfilling this rifle, because I don't think there's a large margin of safety. I did it to demonstrate that the valve was not yet on the power curve.
Also, the way the valve is constructed, each shot will decline in velocity. This rifle has no broad flat spot on the power curve, like many PCPs do. However, I wouldn't shoot it this way if it were my rifle. Instead, I'd use the abundant number of lower-powered shots it offers.
Plenty of good shots at low power
On the lowest power setting, a fresh fill gave 6 strings of 6 shots between 927 f.p.s. and 1068 f.p.s. with 14.3-grain Crosman Premiers and 16-grain Air Arms Diabolo Field pellets. That's a total of 36 shots at that velocity range on low power from a single 3,000 psi fill. Taking a central 1,000 f.p.s. as the average for the 16-grain Air Arms pellets, that's 35.5 foot-pounds.
To get the last string, I bumped the power wheel up to the yellow level, which is three-quarters full power on this gun. The shots were still falling off rapidly, as you see here:
Maybe 30 shots is more realistic than 36, but that's a lot of very powerful shots with what may well turn out to be the most accurate pellets. As a practical hunting gun, you either get 12 shots that average about 60 foot-pounds or 30 shots averaging 36 foot-pounds. That makes the Infinity one heck of a good hunting rifle!
The single-stage trigger breaks after a lot of creep at a light 2 lbs., 10 ozs. The trigger blade is too curved for my taste, but I can't deny that it's lighter than the triggers of 99 percent of all unmodified rimfires.
There's a lot of intrigue to this rifle. Now that the inlet valve has been fixed, we're going to see what it's capable of. Next time, we'll look at accuracy.