by B.B. Pelletier

Photos and test by Earl “Mac” McDonald

Part 1
Part 2

The RWS Diana 350 Feuerkraft is a powerful magnum spring rifle. Today, we’ll begin the accuracy test.

Get ready to learn!
Today’s blog about the .177 RWS 350 Feuerkraft air rifle is going to be very educational, especially for newer shooters. What you’re about to see is a comparison of the potential accuracy when using fiberoptic sights, and then the same gun with the same pellet but using a precision peep sight and a solid black front post.

Because of the length of time this test took, we won’t explore the rifle’s accuracy with a scope today. That will be reported on in a special Part 4 report.

Fiberoptic sights
The 350 Feuerkraft has fiberoptic open sights, front and rear. Fiberoptic sights have special light-gathering tubes inserted in them. When you sight the gun, you see a red dot for the front sight and two green dots for the rear. This type of sight is designed to be very fast to acquire, so hunters use them for rapid acquisition in the field. But there’s a tradeoff.


These two green dots in the rear are supposed to frame the one red dot from the front.


This is the thousand-word picture. Here you see the enlarged front fiberoptic tube that presents a wide dot to the shooter to use as an aim point. With this much width, coupled with the imprecision of locating this dot exactly in the center of the two green rear dots, the shooter has no chance for a precise aiming point. The best you get is a general location.

Less precision
The tradeoff is a loss of precision. Because of the size of the optical dots and the difficulty in centering them exactly the same every time, your sight picture allows for several minutes of slop in all directions. In other words, you can be several inches off with every shot at 100 yards. That won’t matter to a deer hunter who is looking to make a quick shot at an eight-inch wide kill zone. But a target shooter could not do so well with that kind of setup.

As airgunners, we don’t shoot at 100 yards very often, and the amount of slop diminishes as the target gets closer. If there’s a four-minute slop at 100 yards, you would be unable to sight any closer than four inches at 100 yards. So, at 25 yards you would have a one-inch error in your aim point. Some hunters can tolerate that much sighting error, but airgunners often can’t, so you need to give this some thought. Let’s see what Mac experienced.


Ten 10.5-grain Crosman Premier pellets made this 2-inch group with the 350 Feuerkraft rifle at 30 yards. This target is a 10-meter pistol target, which Mac needed because he was using open sights at 30 yards.


Ten 9.3-grain RWS Supermag pellets made this 2-inch group at 30 yards. This wadcutter pellet cuts a nice round hole.


Ten JSB Exact 10.2-grain domes made this 1.5-inch group at 30 yards. This was the best group of the test with fiberoptic sights.

Okay, it’s easy to see that Mac is getting between 1.5 and 2 inches for 10 shots at 30 yards with the standard fiberoptic open sights that come on the 350 Feuerkraft. You probably don’t think that’s very good, and I would have to agree. But, let’s not condemn the rifle for this, because it’s not the rifle’s fault.

Kill the fiberoptics and switch to peep sights
Both Mac and I knew the rifle should be more accurate than this. And, we both know that fiberoptic sights are less than precise. Mac had a good idea — mount a peep sight on the rifle and shoot more groups. I told him my method for turning fiberoptic sights into plain sights by changing the lighting. As long as bright light doesn’t fall on the fiberoptic tubes, they don’t glow. Then the sights act just like regular open sights. In this case, Mac removed the rear sight and used a Mendoza peep sight with the front sight of the rifle. By not allowing light to fall on the front sight, he turned it into a black post that he was able to use like any other front target post. The difference in the results is stunning!


Here are 10 shots with the same JSB Exact heavy pellet and the same 350 Feuerkraft rifle at the same 30 yards. This group measures 0.66 inches center-to-center. Pretty dramatic change, no?

Mac shot a couple of groups; but since the temperature was just 16 degrees, he didn’t test all pellets. He chose to use the pellet that had been the most accurate in the first test, and the group shown was the best group he got, though he says they were all sized similarly.

Amazing difference!
This test shows two things very clearly. First, it shows that fiberoptic open sights are not very precise. That’s why I’ve objected to their use on air rifles for so many years. We need enough accuracy to hit ants at 25 yards, and fiberoptic sights have only tin-can accuracy at that distance. That should be very plain and clear to everyone who’s read this report. Mac is a great shooter, as we have seen over the past several months, and fiberoptics were a huge limiting factor to shooting the 350 Feuerkraft well.

The second thing to take away from this report is that the 350 Feuerkraft is a very accurate spring rifle. Putting 10 shots into 0.66 inches at 30 yards is equivalent to putting 5 into a third of an inch at the same distance. So, this rifle can shoot! No question about that. Mac suffered a scope failure when he was testing the rifle with a scope, though he did get a couple half-inch 10-shot groups before that happened. We’re getting him a replacement scope for a part four report.