Diana 300R repeating underlever: Part 2

by B.B. Pelletier

Part 1

Today you’ll read part 2 of Vince’s guest blog. As usual, he’s done an extremely thorough job.

If you’d like to write a guest post for this blog, please email us.

Bloggers must be proficient in the simple html that Blogger software uses, know how to take clear photos and size them for the internet (if their post requires them), and they must use proper English. We’ll edit each submission, but we won’t work on any submission that contains gross misspellings and/or grammatical errors.

by Vince

You’ve loaded the magazine, and now you’re ready to shoot. Almost.


Lock & load!

Suppose the rotary mag wasn’t indexed quite right when you put it back into the gun? That could be a problem. To make sure there isn’t a problem, get into the habit of pulling back on the cocking lever after reinstalling the mag, as if you’re trying to reset the sear. As mentioned in part 1, this last little bit of travel is what indexes the mag, and the action will rotate it to the next position and line it up properly. If the mag is halfway between pellets, the feeding pin is going to be blocked from going forward. This means that the lever is not going to want to move toward the firing position. But only a little. Because of the immense amount of leverage in the cocking lever, there won’t be much resistance, you might force it and break the pin without even realizing it.

Now you’re ready to start making holes…and making holes is something the 300R does rather well.


Pretty good 6-shot group with Crosman Premier hollowpoints.

The above target is a quick 6-shot group at 10 meters with open sights using Crosman Premier hollowpoints. It can do even better — and I’ve done better. More on that later. The rifle is about as hold sensitive as any other non-breakbarrel Diana springer, which is to say not too bad. Just remember that you have seven shots with no indication when those seven are done. To make sure the mag is empty, you’ve got two choices: dry-fire the gun (a no-no, although it will happen by accident on occasion) or remove the mag.

making holes is something the 300R does rather well

Fortunately, you don’t have to completely cock the gun to do so. Back when I described the picture of the pin retracting, I pointed out the position of the cocking lever. I was only starting to pull it back, but the pin was retracted almost all the way. Fact is, the pin is out of the way well before the lever is even halfway cocked. So, you CAN remove and replace the mag without cocking the gun if you hold the lever in the partially cocked position. Familiarize yourself with exactly where this is before making a habit out of it. Don’t let the lever go while you’re in the process of removing or reinstalling the mag.

So far, I’ve described how this gun is supposed to operate. What goes wrong and what do you do when it does go wrong?

The most obvious boo-boo is to try to remove the mag with the lever all the way forward. A real easy mistake to make. What does this do? Well, first of all the mag doesn’t want to come out because the pin is running through it. Second, the thin, brittle pin probably breaks. The next real easy mistake to make is to say to yourself “Oh! Right! I forgot to cock the gun!” So, you cock the gun, but the now-broken pin is still lodged in the rotary mag and won’t let it index to the next position. Again, you’ve got so much leverage in the cocking linkage that you don’t notice the increase in resistance. You force it without realizing it, and you break the magazine. Yet, it still doesn’t want to come out. Since you’re probably holding the gun muzzle up while you shake the gun, pump the lever and fiddle with the mag — that broken pin will eventually come loose…and fall into the guts of the gun.

Hoo-boy. Now you’ve got three major problems, and you’ve collected them all in the space of about 45 seconds.

Some time ago, I wrote up a sheet of cautions and procedures to follow with this rifle, and I tried to cover every contingency. I’ve listed those instructions at the end of this blog, so I won’t rehash everything here.

The last thing I want to talk about, though, is what happens when the gun is operated without that pin. In that case, the air will blast the pellet out of the mag. The cylinder pellet holes are sealed pretty well at the front and rear of the magazine.



Front and rear seals help stabilize the rotary mag.

That rear seal is on the end of a spring-loaded plunger. When the lever is forward, the rotary is firmly sandwiched between these seals. Combined with the relative power of the rifle (compared to an Umarex pistol or a Crosman 1077), it should make for a nice, strong burst of air that will reliably feed the pellet from the cylinder to the breech…pin or no pin.

The only possible fly in the ointment, as far as I can see, is that the rapid blasting of the pellet into the breech might be more inclined to damage the pellet if there’s a significant mismatch between the hole in the cylinder and the barrel bore than if it was gently fed by the loading pin. Theoretically, this could affect accuracy. I’ve tried it both ways and could not detect any difference. In my basement range, I managed to shoot a .18″ group (don’t remember if it was 5 or 7 shots) at 12 yards with a pin-less gun with a scope. Frankly, I just don’t do any better than that. So, no, I don’t think the accuracy issue is a significant one.

That wraps it up for the 300R. It’s a unique experience that definitely keeps you on your toes. Like many unique relationships, it’s frighteningly easy to mess things up, but there’s no need for despair. One way or another y’all can patch things up again and literally find yourself repeating the experience.

Below is my list of things to remember when shooting the Diana 300R.

Read all factory instructions. The RWS 300R has a unique mechanism that can be accidentally damaged by mishandling.

The pellet is loaded from the magazine into the breech by a very thin, brittle pin that cannot tolerate any significant side loading. This pin is retracted when the cocking lever is pulled back and pushes the pellet forward as the cocking lever is returned to its normal (or firing) position. With the cocking handle in its normal position, this pin runs through the magazine.

Never attempt to remove the magazine unless the gun is cocked and the cocking lever is to the rear — or you will probably break the pin.

If the mag holder is inserted when the cylinder is not properly lined up, the feed pin might hit the cylinder between two pellets — or it might hit a pellet off-center and jam or mangle the pellet on loading. Here’s how you prevent this: After reinserting the magazine, pull the cocking lever all the way to the rear as far as it will go (just as you would when cocking the gun). This ensures that the magazine is indexed properly.

A cocked gun may be uncocked without firing and with the magazine installed or removed. Pull the cocking to the rear until it just reaches the point of meeting resistance from the piston and spring. Holding it firmly (just as you would while cocking the rifle), push in the safety and pull the trigger. This should release the handle. Let it return, under pressure, to the uncocked position.

The rotary magazine is indexed (rotated to a new position) during the cocking cycle just before the trigger engages. If the rearward part of the cocking stroke meets with unusual resistance right before the trigger catches and doesn’t want to fully cock, stop pulling the lever or the magazine might break. Something has probably jammed the magazine and won’t let it rotate.

Try to remove the magazine with the lever pulled back MOST of the way. If it’s difficult to remove, stop, reseat the mag, allow the lever to return to its normal position and service the gun (or have it serviced). The 300R is not a particularly difficult gun to disassemble, and the powerplant does not have a lot of spring preload (about 50 lbs.). If you’ve disassembled other spring-piston air rifles, you’ll probably be able to service this one.

If the magazine does come out, let the lever return forward. Is the loading pin visible in the magazine port? If it is, try recocking and decocking the gun without the mag. If it feels normal, empty and reload the magazine and try again.

Never attempt to remove the magazine unless the gun is cocked and the cocking lever is to the rear — or you will probably break the pin.

If the pin is not visible, it’s broken. Sometimes, the 300R will feed and fire just fine without it, but the owner must first make sure that the broken pin is not inside the barrel or inside the gun (trapped in front of the sliding cylinder). The barrel bore can be visually inspected. In order to check the cylinder, bring the cocking lever all the way forward and lock it into position. Look in the magazine port, and you should see the air nozzle with a blue seal protruding into the rear of the port. The outside metal shell of the nozzle should be protruding into the mag port by about .050 inches. If it’s much less than this or not protruding at all, the pin is probably in the gun and it needs to be disassembled.

Otherwise, the pin probably just fell out or was discharged behind a pellet. You may try operating the rifle without this pin. If it functions properly, go ahead and use it. The only risk is that if the pellet doesn’t discharge it might be lodged halfway into the breech. Given the relatively high power of this gun, this isn’t very likely, If you think it happened, do not recock the gun. Pull the cocking lever back slightly and try to remove the mag. If it comes out, you can easily check the mag and barrel for a damaged or jammed pellet. If it doesn’t want to come out, go in from the muzzle with a cleaning rod and push the jammed pellet back into the mag.


Diana 300R repeating underlever: Part 1

by B.B. Pelletier

Vince is back with 2-part blog about another gun he’s repaired. I get a lot out of Vince’s guest blogs because he gets to play with and repair guns that I don’t have! I learn a lot and I’m glad to see that there’s someone who can do such fine work and be incredibly resourceful at the same time. He sets the standard high. For those of us who don’t work on airguns, it’s just nice to know that there’s someone this good who does.

If you’d like to write a guest post for this blog, please email us.

Bloggers must be proficient in the simple html that Blogger software uses, know how to take clear photos and size them for the internet (if their post requires them), and they must use proper English. We’ll edit each submission, but we won’t work on any submission that contains gross misspellings and/or grammatical errors.

by Vince

Guys know the type. Pretty to look at, but not overly flashy. Demure, faithfully consistent, does just about everything she promises to do, never lets you down, very forgiving and seems to be just about the perfect partner for a lifelong commitment.

Then it happens. One small misstep — one slight slip of the mind, an apparently insignificant momentary lapse in judgment or prudence, and BAM! It’s all over. The relationship lies in pieces, the damage is done, and the joy of newfound attraction is gone forever. IF ONLY YOU HAD KNOWN!

Well, after this article YOU WILL KNOW! And, fortunately, it doesn’t have to end this way. One can, indeed, live quite happily with the Diana 300R repeating underlever.

Repeater… the “holy grail,” in a sense, of better air rifles. A repeater that takes all pellets. A repeater that sacrifices nothing in accuracy. A repeater that’s easy to load and doesn’t misfeed and doesn’t mangle pellets. A repeater that…well, you get the idea.

The RWS/Diana 300R hit the market a few years ago as an upper-tier gun in the Diana line. I’m not sure what it cost, but it I believe it was in the range of $400. Whatever it got, it didn’t get for long, as the rifle disappeared from the catalogs after a relatively short run. All due to that hypersensitivity to even the slightest mishandling — if it was the wrong kind of mishandling.

The 300R is a fairly heavy underlever springer with a T05 trigger and a 7-shot .177 rotary mag. It’s equipped with Diana’s standard iron sights — open blade front and a rear adjustable for windage and elevation. As expected for a Diana underlever, it’s on the hefty side, with a weight of around 8 lbs. All that’s pretty standard in the way of specs.




Nice wood!


The real trick to this rifle is in the magazine that loads from the top.

See where my finger is in the above photo? It’s pushing back on the top cover of the magazine, which is how the mag is released so that it can be removed from the gun. But wait! If you wanna mess things up real bad, this is the time you’re going to do it.

Notice where the cocking lever is. Yes, it’s in the cocked position (fully rearward). The position of that lever is very important when removing or replacing the mag. Don’t do either when the lever’s in the forward position. Sounds rather strange, doesn’t it? Let’s see why that is. First, take a look at the mag.


Correctly loading the mag is crucial to proper operation.

Shown above, the pellet carrier is actually a revolving cylinder similar to the Crosman 1077 and several Umarex pistols.


The magazine well with the mag removed and with the lever in the stowed position.

That thin (and hardened and, thus, brittle) metal rod running through the well is the feeder pin. Obviously, this pin runs through the mag when the lever is forward, which is why you can’t remove the mag when the lever is up. What does the pin do?


As you pull back the cocking lever, the pin retracts.

As you can see, as the cocking lever is pulled back the pin starts to retract into the rear of the action. Note the position of the lever. Also notice how the tip of the pin is this nice, rounded, bulbous shape. There are a couple of reasons for that, which I’ll get into later.

With the lever all the way back the pin is completely retracted, and the mag can be removed without incident.


Don’t remove the mag before the cocking lever is all the way back.

Likewise, the pin moves forward again as the lever is returned to the stowed position. This pushes the pellet out of the mag and into the breech of the rifle, from where it’s fired. That’s why the tip of the pin is rounded, so it doesn’t damage the pellet as it pushes it forward. Since the pin stays in place while the gun is fired, air has to flow around that pin to get to the pellet. That’s reason No. 2 for the nice, rounded tip — less drag on the airstream.

Go back to the picture of the magazine. See the indexing tab? As that tab is pushed upward, the cylinder rotates (indexes) to the next pellet. That happens at the very end of the cocking stroke, after the trigger sear latches. Which is important to know, as I’ll explain in a minute.

The mag itself is loaded with pellets in the usual way:

The cylinder is placed back into the carrier:

Make sure it’s seated all the way. You might have to rotate or wiggle the cylinder a bit to get it to seat properly. The entire magazine is then reinserted into the gun — AGAIN, with the lever pulled back!

Stay tuned for the rest of this story in tomorrow’s blog!