by Tom Gaylord
Writing as B.B. Pelletier

Part 1

Diana 45 left
Diana 45 is a large breakbarrel spring rifle.

This report covers:

• Velocity with Premier lite pellets
• RWS Superdome pellets
• Air Arms Falcon pellets
• RWS Hobby pellets
• Cocking effort
• Trigger-pull
• Evaluation so far

Today, we’ll look at the velocity of the Diana 45 I’m testing. I think you’re in for a surprise. I know I was startled when I saw the numbers. I’d forgotten so much!

The 45 was a magnum air rifle for its day, but in that day 800 f.p.s. was considered the fastest velocity that airguns could achieve, and only a few of them, like the Diana 45, could do it. Air Rifle Headquarters catalogs of the late 1970s show Diana 45s getting up to 860 f.p.s. after their qccurization (their name for a tuneup), but stock guns were only able to get just above 800.

As large as this rifle is, you get the feeling that it should be just as powerful as a Diana 34; but as you’ll see in a moment, this one certainly isn’t. The reason for that is a short piston stroke. When the barrel’s broken open to cock the rifle, it stops just beyond 90 degrees. Most breakbarrels today break open to 120-150 degrees. That means their pistons are being pushed back farther for a longer stroke and more power.

Diana 45 left cocking comparison
When Mac tested a .22-caliber Diana 45 back in 2010, he took this picture of both the 45 and the Diana 34 fully cocked. Note how much farther back the 34 barrel goes. This is the difference between a short- and long-stroke piston, and it makes all the difference in power.

Velocity with Premier lite pellets
The first pellet I tested in the rifle was our good old standard — the Crosman 7.9-grain Premier. The initial velocities I was getting were 706 to 721 f.p.s. — lower than I expected. But there’s a good chance this rifle has a leather piston seal; and if it does, that seal needs to be oiled to do its job. So, I put several drops of RWS silicone chamber oil down the transfer port using the steel needle that comes with the oil bottle. Then, I cocked and uncocked the rifle several times to spread the oil around. Having done that, we could then see if this gun was dry.

The first several shots were all over the place, with a couple detonations thrown in for good measure. Then, the rifle settled down and gave me 10 good shots with Premier lites, which averaged 771 f.p.s. The increase is enough to tell me the rifle was dry before. That means it might have a leather seal, though nothing’s certain without looking. Also, on this string the velocity varied only 7 f.p.s. — from 767 to 774 f.p.s. At that velocity, this pellet generates 10.43 foot-pounds of energy at the muzzle.

RWS Superdome pellets
Next up were RWS Superdomes. These pellets are pure lead, where the Premiers are a hard alloy. They weigh 8.3 grains and averaged 735 f.p.s in the 45. The spread was 18 f.p.s. and went from 725 to 743 f.p.s. At the average velocity, Superdomes produced 9.96 foot-pounds of muzzle energy.

Air Arms Falcon pellets
I tried Air Arms Falcon domes next. They averaged 785 f.p.s. with a 30 f.p.s. spread that went from 773 to 803 f.p.s. Right there, the 45 broke the 800 f.p.s. “barrier.” In the days when it was new, that qualified it as a magnum.

At the average velocity, Falcons produced 10.03 foot-pounds of energy. I expected a bit more power from them because they’re lighter than the Premier lites; but to this point, the Premier lites are the power champs.

RWS Hobby pellets
The RWS Hobby pellet was the ultimate test for velocity when the Diana 45 was new. I expected them to be the fastest in this rifle and they were, with an average of 793 f.p.s. The velocity spread was 28 f.p.s. and went from 778 to 806 f.p.s. At the average velocity, the Hobby generates 9.78 foot-pounds of energy, so the old rule of light pellets being the most powerful in spring guns doesn’t hold true in this one. At least, not at this time. Maybe that’ll change after I tune the rifle.

If this rifle seems weak to you, it really isn’t. I would say it’s on the low side of normal for this model. You may read things on the internet about fabulous tunes and how they can break 1,000 f.p.s. in .177; but every time I run down one of these rumors, it turns out to have a flaw. The most common is a Diana 45 that’s actually the model 34 that carries a 45 model number. Some folks just can’t recognize the distinction between this old model 45 and the one that followed it after this one was terminated in 1988.

Cocking effort
The rifle cocks with around 32 lbs. of force right up until the trigger is cocked and the safety is set. Then, the scale needle spikes up to 35 lbs. But that comes at the end of the cocking stroke, just as the cocking leverage starts to improve (remember how far this barrel breaks!). The cocking effort feels heavy to me.

Trigger-pull
The trigger on the test rifle is adjusted very well, with a 2-stage pull that breaks at 3 lbs., 3 oz. There’s a hint of creep in stage 2, but I’ll disregard it, because the adjustment is so nice as it is. I might lubricate it during the tune, but I absolutely will not “stone” the sear or any other trigger parts! These rifles have parts that are case-hardened to a very shallow depth, and stoning or (shudder) filing the metal parts can cause real safety problems. Best to leave well enough alone.

Evaluation so far
I never liked the Diana 45 when it was available. Every one I shot was buzzy — including this one. But I shot them back in the days before the Beeman R1 took air rifle velocities up to 1,000 f.p.s. So, this was a real magnum.

The R1 is a much more solid rifle. It’s heavier, larger and has a better trigger. Also — and this is really what drove my opinion — the R1 is easy to disassemble, where the Diana 45 does require some technique. Back in the day, I didn’t have a fancy mainspring compressor, so I made my own super-clunky one. It worked, but it didn’t invite tuning many guns.

However, as an airgun writer, I found I could not ignore the Diana line. In the early 1990s, they were considered entry-level spring guns, both because of their low price and also because there were no decent Chinese rifles around to challenge them. El Gamo did make air rifles, but back then they were lower-powered guns.

As competition came to the market, Diana upgraded their air rifles, but this model 45 was left behind. It was never upgraded the way the model 34 was. Now, I find myself face-to-face with a rifle from the past. It doesn’t know what year it is, so it’s going to do what it was designed to do. But, over the 26 years since it was last sold new, we’ve learned so much more about how to properly tune spring-piston air rifles that I think we’re in for a treat.

What I’m saying is don’t expect to see a big increase in power. But do anticipate a Diana 45 that shoots as smooth as glass!