Diana 27 (pre-war)

This strip relates to the pre-war Diana model 27, a break barrel rifle produced throughout the 1910s up to 1930s. for more information, see Hiller or the excellent articles written by John Atkins in the Collectables series in AirGunner . Its most distinguishing feature is what I term the ‘slab sided’ trigger block housing ... flat sided with a curved top. It really is one of the easiest of rifles to strip and rebuild.

To strip for a service (mainspring replacement, piston head inspection/replacement) it is not strictly necessary to remove the stock. But if you want to remove it, proceed as:
Remove butt plate (2 screws). Remove trigger guard (remove the trigger adjusting screw first in order to get at the front guard screw). The butt is held on by a nut attached to a threaded rod: undo it (I used a 17mm box spanner). The stock then slides off the rod.
There is no need to remove the trigger from its housing but if you wish to, simply undo the trigger pivot bolt and remove it; the trigger will come out of the underside of the housing with its spring. The housing simply unscrews from the cylinder. You may need to pull the trigger back as you begin the removal in order to avoid the cylinder. Spring tension is not great but I always secure the cylinder in a padded vice for extra control. With the housing removed, (the spring guide is integral with the housing), lift out the mainspring. I have used a Meteor mainspring as replacement when needed but take care not to ‘overspring’ the rifle with a ‘too strong’ a spring.

To remove the piston, release the cocking arm pivot screw and lift out the arm. You could, if you wish, remove the breech/barrel from the breech jaws by removing the keeper screw and then the barrel pivot bolt. The piston then slides out.
The piston washer will be leather ... a central cylindrical leather disc and an outer cup washer. Both are readily home made if you need a replacement. There is a screw holding them to the end of the cylinder. The breech seal is leather ... again easily made if faulty. I did not remove the cocking latch but if you need to, there is a single screw that secures it. Take care during removal that the latch does not ping away.
After cleaning and effecting any replacements, reassembly is a direct reversal of the strip.
In order to screw the action back onto the trigger housing, I found it easiest to clamp the housing in a padded vice .. the slab sides make this easy ... and offer up the cylinder to the housing. When replacing the trigger (if you removed it), I found it easiest to put the trigger in position on the pivot bolt then wiggle the spring into position, taking care to ensure it locates correctly. Alternatively you may find that you can put the spring in position on the trigger blade, engage the other end in position in the housing and then move the trigger blade into position to put the pivot bolt through. Replace cocking arm and stock (if removed,). Add trigger guard, ensuring it fits snugly into the stock ... note that the securing screw at the rear of the action passes through the stock to engage with a thread in the trigger housing. Replace the trigger adjustment screw. This acts to reduce sear engagement when you screw it in, so take care not to screw it in too far and so produce an unsafe trigger. My examples, in .177, produce about 600 – 670 fps depending on pellet.
Job done.
Cheers, Phil