by Tom Gaylord, The Godfather of Airguns™
Writing as B.B. Pelletier
This report covers:
• Standard velocity test
• Second test
• What does this mean?
• Third test
• Fourth test
• Fifth test
• Making sense of the data
• Other observations
Today, we’ll look at the velocity of the Umarex NXG APX air rifle, and I learned some interesting things.
Standard velocity test
First, I did my standard velocity test. That’s where I pump the rifle a number of times and record the velocity for each set of pumps. For this test, I always use a Crosman Premier 7.9-grain pellet — assuming a .177-caliber air rifle, of course. Let’s look at the results of that test.
Pump head dried out
As I shot this series, I noticed the air intake grew less dramatic as the pumps increased. I didn’t do anything about it right away; but in the next string, I decided to oil the pump head. You’ll see the difference that made. Just so you know. I did not oil the pump head before starting the last string, because I’d already oiled it in the last test session, which was a week ago.
What I do in the second test is pump the gun the same number of times and record the velocity for a string of 10 shots with the same Premier lite pellet. This string is where I noticed that the pump head seemed to be drawing in less air with each shot. For each shot shown below I pumped the rifle 5 times.
Oiled the pump head at this point.
What does this mean?
It’s very clear that oiling the pump head boosts velocity. And the reason for that can only mean one thing — more air is getting into the valve’s reservoir. Why more air gets in would seem to be because the pump head is doing a better job of sealing the compression tube on every pump stroke. Oil will certainly do that. I need to keep an eye on this for the rest of the test.
For the third test, I used a lighter pellet — an RWS Hobby wadcutter. Umarex sent a tin of them with the rifle. Normally, I would expect this pellet to go much faster than the 7.9-grain Premier lite used in the first 2 tests.
Instead of doing the entire first test again, I pumped the rifle 3 times and shot, then 5 times and shot and finally 10 times and shot. That should give a good cross-section of the entire pump test done previously.
Something didn’t seem right about this test. In all cases, the lighter Hobby pellets went slower than the Premiers. I thought it might be the oiling, which I planned to do another time, so I moved on to the lightest pellets I had — RWS HyperMAX lead-free pellets.
RWS HyperMAX lead-free pellets weigh 5.2 grains and are among the lightest pellets around. They should really scream in the APX, and in fact they are the pellets that Umarex advertises as getting 800 f.p.s. in this rifle. As with the Hobbys, I pumped 3 times and shot, 5 times and shot and finally 10 times and shot.
10 626, 569, 561
As you can see, the velocity is dropping off again. So, I oiled the pump head once more and switched to BBs.
For this test, I loaded 10 BBs into the reservoir, because the APX is a repeater when it’s shooting BBs. I used Umarex Precision Steel BBs that came with the rifle. The pump head is freshly oiled for this test.
The BBs come out of the reservoir in a long line, but are limited by the width of the pellet trough. The bolt pushes one BB ahead into the breech and the rest have to wait their turn.
7 814??? (585 on the second try)
It seems the pump head dried out in the middle of this string, so I oiled it again and pumped the rifle 10 more times. The final shot on ten pumps went 741 f.p.s.
Making sense of the data
It would seem from this brief test that the rifle I’m testing needs very frequent oiling to maintain its maximum velocity. It also seems that 800 f.p.s. is beyond the rifle I am testing for you. BBs seem to have shot faster than any pellets, which is exactly what I expected would happen.
I doubt anyone is going to shoot their rifle with an oil can in hand, so these data must be taken with a grain of salt. Therefore, I did one final test string of 10 shots with the Premier lite pellet that seemed to give the most favorable results. I did not oil the gun for this test…but it’s been oiled already 3 times today, so it should be good to go.
Ten shots averaged 604 f.p.s. and ranged from 597 to 614 f.p.s. So, the rifle seems to have settled down to that velocity. When I look back at the Daisy 880 test I did earlier this year, Premier lites went 645 f.p.s., so the velocity of the APX is approximately equivalent.
The cocking effort got much smoother as this test progressed. I didn’t mention it but I actually shot the rifle an additional 35 times on 10 pumps per shot, just to try to break it in a bit.
The trigger-pull measures 2 lbs., 3 oz. for stage one, and stage two breaks at about 8 lbs. — though it varies several ounces shot-to-shot. At this point in the test, I have to say the APX reminds me a lot of the Daisy 880. Accuracy comes next, and I have to test the rifle with both pellets and BBs and also with the scope. So, there are several more sections coming.