by Tom Gaylord
Writing as B.B. Pelletier
Diana model 30 gallery gun.
This report covers:
- Caliber 4.4mm
- The fix
- Power was intermittent
Apparently there have been three Dianas model 30. Blue Book of Airguns calls them out and tells us the differences. Last week there was some confusion about which Diana model 30 airgun I was referring to in a comment, and when I clarified it one of our readers asked for a report. It happened that I then visited a friend who has a model 30 gallery gun, and he told me it wasn’t working. I said I would try to get it working again if I could test it for the blog, so here we go.
The Diana model 30 gallery gun is a spring-piston rifle that uses a bolt to cock the mainspring. It’s similar in function to a great many other bolt-action airguns like the Schmeisser model 33, the Anschütz model 275, the Haenel model 310 that copies the Anschütz, and even the Czech models VZ35 and VZ48. All of those airguns are rifles like this one, but if we expand the list to include smoothbores we have to acknowledge the Mars models 85, 100 and 115. There are probably others I haven’t mentioned.
The gun we are looking at today was made from 1972 to 2000. According to the Blue Book there was a limited availability of them until 2003, which might be the remaining supplies being sold off. This model is virtually unheard of in the U.S., but common in parts of Europe and, oddly, in the UK, where they are seen in amusement park shooting galleries. This is a purpose-built gallery airgun that even has two shot counters — one to count the shots so the customer can be charged and the other to count the total shots on the gun for periodic maintenance purposes. That one is like an hour meter on a piece of equipment.
Shot counters for selling shots and for maintenance.
Remarkably all these guns (that I know of) shoot 4.4 mm lead balls. I guess that is not unlike our American BB guns that all use 0.173-inch steel BBs. And I have a lot more to say about that.
The gun I was loaned had some balls in the magazine tube underneath the barrel that could be seen through slots in the tube’s side when the muzzle was held down. When I tried cocking and shooting the gun though, nothing came out — just like the owner told me.
Three “windows” let you see what balls are in the magazine.
I figured the fix for any low-powered spring gun could be ATF sealant on the piston seal. This stuff fixes both CO2 and pneumatic seals, and I reckoned it would also fix spring-piston seals on lower-powered guns, regardless of whether they are leather or synthetic. I found no place to oil the piston, so I dropped about 10 drops down the muzzle and stood the rifle on its butt for several hours.
When I then cocked and shot the gun hours later it started firing intermittently. The number of good shots kept increasing until it was finally shooting a ball every time.
The bolt is down when it is at rest.
Lift the bolt up with no resistance. Now it can be rocked back to cock the rifle.
The bolt is rocked back, compressing the mainspring. Return it to the down position and the rifle is ready to fire.
Power was intermittent
I noticed that some balls were shooting much harder than others. At first I thought the piston seal was just getting soaked with oil, but this persisted and I looked for the reason why. I discovered it quite by accident.
Most of these gallery guns are rifled and shoot balls. And they are all repeaters. They all have different magazines, and the model 30 has a gravity-feed tube that holds up to 125 balls.
I wanted to look at the rifling, so I shot a ball into a cloth to catch it for photography. That ball told me more than I bargained for.
The arrows point to either side of the band of rifling engraving around the ball. This rifling is not engraving deeply enough!
At first when I looked at the shallow rifling cuts under a jeweler’s loupe I thought, “Wow — Diana sure made some fine rifling in this barrel!” Then it dawned on me — the rifling was fine because the balls were too small for the bore! These balls were undersized. That could also cause the power to be low. So I measured the balls and, sure enough, I was loading balls of different sizes! And probably so had the owner of the gun without knowing it.
I have two different brands of German lead balls whose tins both say they are sized 4.4mm. I have been shooting one brand for the past 20+ years. But when I measured these “4.4mm” balls, they actually measure anywhere from 4.34mm to 4.41mm Most measure 4.39mm which is close, but we aren’t playing horseshoes or throwing hand grenades.
Sure enough, these “4.4mm” lead balls are on the small side.
The 4.4mm balls in the other tin I have all measure 4.4mm+. They also seem to shoot harder in this Diana 30, and the rifling has engraved them much deeper.
The copper-plated balls on top tend to be smaller than 4.4mm. The balls in the bottom tin are larger.
The unplated lead ball is larger and grabs the rifling much better. Sorry the image is not sharp. This was a macro hand-held.
This report sounds like a repair job, when it actually was more about learning an airgun I did not know and had no documentation for. In the beginning I didn’t even know how to load it. The owner wasn’t sure either, but a drawing showed both of us that the balls go in the end of the tubular magazine. A small wire spring keeps them from falling back out.
I prepare to load a ball. I didn’t know these copper-plated balls were too small when I took this picture.
The ball is dropped into the top of the magazine, where the spring stops it.
A small tool pushes the ball past the spring into the magazine. Gallery owners no doubt had speedloaders for this.
How about that? I didn’t even get through Part 1 this time. I thought this report would be cursory, but apparently not. On Monday I will finish describing the Model 30.