by Tom Gaylord
Writing as B.B. Pelletier

Diana 27
My .22 caliber Diana 27 is actually a Hy Score 807.

Part 1

A history of airguns

This report covers:

  • RWS Superpoint
  • RWS Superdomes
  • Crosman Premier
  • Am I satisfied?
  • Cocking effort
  • Trigger pull
  • The ball bearing trigger
  • How to adjust the ball bearing trigger
  • Summary

Today we look at the velocity of my vintage Hy Score 807 breakbarrel air rifle that you now know is a Diana 27. Besides that I will test the trigger pull, the cocking effort and I will tell you how to adjust the ball bearing trigger. That, alone, is worth what you paid for this entire blog, so settle in and let’s have some fun!

RWS Superpoint

The first pellet I tested was my go-to pellet for a .22 caliber Diana 27 and many other old air rifles — the RWS Superpoint. I believe that Superpoints have such thin skirts that they seal the bore better in these lower powered spring rifles. I told you about the lithium grease “tune” I did about 20 years ago. It’s still performing well after all this time, and I never oil the leather piston seal. As I recall, the Superpoint averaged around 475 f.p.s. in the past. Today 10 pellets averaged 468 f.p.s. The spread went from a low of 458 to a high of 474 f.p.s., which is 16 f.p.s. So, the rifle is still pretty much where it has always been. At the average velocity this pellet generated 7.05 foot pounds of energy at the muzzle.

I noticed that Superpoints fit the breech poorly because of their wide skirts. The bottom of the skirt hung outside the barrel because of Diana’s slanted breech, and of course that part of the skirt was bent when the barrel was closed. I deep-seated one pellet with a ballpoint pen so it was all the way inside the breech and lost 80 f.p.s. (383 f.p.s.). So that was out.

RWS Superdomes

I haven’t really shot RWS Superdomes in my Diana 27 in the past. That’s because their skirts are much thicker (in .22 caliber) than Superpoint skirts. But Superdomes have proven to be so accurate in other vintage air rifles that I felt I had to try them today.

Ten Superdomes averaged 469 f.p.s. in the model 27. The spread went from 463 to 474 f.p.s., so a spread of just 11 f.p.s. At the average velocity this 14.5-grain pellet (same weight as the Superpoint) generated 7.08 foot pounds at the muzzle. That is so close to what the Superpoint did, though the Superdomes had the smaller spread. And they fit the breech a little better.

Crosman Premier

The .22 caliber Crosman Premier weighs the close to what the two RWS pellets weigh — 14.3-grains compared to 14.5 grains for the RWS pellets — but it’s made from lead that’s been hardened with antimony. The performance will be different for that reason, alone. These averaged 442 f.p.s. in the 27. The spread went from a low of 429 to a high of 472. That high shot was anomalous, however, because the next-fastest shot went out at 449 f.p.s. So the overall spread was a large 42 f.p.s. At the average velocity Premiers generated 6.2 foot pounds at the muzzle. This pellet fit the breech the best of all, though its head did seem to fit a little tighter.

Am I satisfied?

Actually I’m very pleased by the performance of my model 27. It has held up well over two decades from a simple lube tune. But I have a thought. I would be curious to see if I can clean out the lithium grease and perhaps replace it with Almagard 3752 to speed things up a bit. If that happens it will be because less grease will have to be used to keep the powerplant quiet. I might even buy a new mainspring, though this one seems to be okay.

I need to think this through. It wouldn’t stop this series, because I can still shoot the rifle for accuracy with open sights as it is now. And don’t even bother asking — there ain’t never gonna be no scope on this one! Those are just a few of my thoughts.

Cleaning the gun would give us a chance to see what 20-year-old grease looks like. I’m betting the Almagard grease will speed things up a little because I won’t need nearly as much to quiet the rifle. This would also give me the opportunity to take more pictures of the ball bearing trigger that I always need to explain it to shooters.

Cocking effort

The rifle cocks with 17 lbs. of effort, as measured on my bathroom scale. That puts it solidly into the youth rifle category, though the rifle’s dimensions are right for adults.

Trigger pull

The trigger on this air rifle breaks in an interesting way. The very long first stage takes 1 lb. 15 oz. to arrive at stage 2. Stage 2 then breaks cleanly at 2 lbs. 14 oz. I guess it is the positive-ness of the stage 2 stop that I like so much. Once you are there, you can feel no resistance from the trigger. So, the trigger breaks with what feels like a 15 ounce pull.

The ball bearing trigger

I showed you the parts of this trigger in Part 1, so go back and look if you don’t remember. How it works is the three ball bearings press into a groove at the base of the piston rod when the gun is cocked. The balls are situated on top of an inner sheet metal cage and inside another outer cage. When the outer cage is able to move as the trigger gets out of its way, a spring pushes it away from holding the balls in the groove and the piston is released. It is an ingenious design that allows sheet metal parts to function just like solid steel parts that have been machined.

How to adjust the ball bearing trigger

This is where I earn my pay. For years I struggled trying to adjust several Diana 27 and 35 ball bearing triggers. Then someone gave me an owner’s manual and I learned the secret.

Diana trigger screws
The front screw (on the left — closest to the muzzle) is a locking screw. The rear screw does all the adjustment.

Here are simple instructions for adjusting the vintage Diana 25/27/35/50 ball bearing triggers that have two screws. The front screw is just a lock screw. Loosen it, and then screw the rear screw in as far as it will go (that’s clockwise). Then, turn it back out two full turns and try cocking the rifle. Be careful not to let go of the barrel, because some guns may be adjusted to the razor’s edge this way. If yours is and you need a little more sear engagement, try turning the screw in or out just a quarter turn until the sear holds well. Next, tighten the front screw, and the job is done. You’ll have a long first stage followed by a definite stop and crisp stage-two break when the gun fires. You only have to experience one of these triggers adjusted correctly to know how nice they all are.

What can’t be controlled is the length of the first stage. It has to be long, if you want that crisp second-stage release. I don’t mind that one bit, though it is different than the trigger on any other airgun I can think of.


So far, so good. Everything is on track and the rifle is performing as expected. I am interested to hear your thoughts on whether I should relubricate my rifle. I’m sure most will want me to. In the past I avoided taking Dianas with ball bearing triggers apart, because there are so many parts in that trigger they can be difficult to assemble again. The trick is to use sticky grease in the trigger to hold the parts in place until they are inside the spring tube again. Once inside, the spring tube holds everything together. Almagard 3752 grease is so tacky that I know the rifle will be easy to assemble this time, so no worries.