Diana52 twist rate

Do you know how to figure it out with a cleaning rod?

I have a 52 .25 but not sure it's the same as the .22's

I'm thinking mine and all are 1:16 or slower as I don't seem to get a full revolution on a pull through. Mine is a factory .25 and I honestly don't know what barrel brand Diana used for these rare .25's. Mr. Vines owns a gorgeous special custom 12" shrouded LW 52 .25 and I know he knows these guns inside and out. He'll gladly jump in if he sees this. 
They're all RH twist. That's the standard but some long range shooters do prefer a custom LH twist depending on the geographical location of shooting. 

Here's a great fun article that explains why: 

https://www.americanhunter.org/articles/2014/2/4/why-is-rifling-twist-direction-usually-right-handed/

Are you punching the #'s into a shooting app? The 52's are have a much nicer fit stock wise over the 48's. I use to think it was just a checkered stock but nope. Longer, different grip, checkering, weight difference. If I had known that I would have grabbed several but I have 3 48's instead
 
Yes, the above means 1 full turn in 16". Take a cleaning rod (ball bearing types seem to work best to allow easy rotation but any will work if handled lightly) and pull a brush through the barrel with a marked spot on the rod near the breech (or muzzle if working from that end). Pull the rod through the barrel until it makes one full rotation. Measure the distance you pulled it. That is the twist rate. Not sure what it is for the above mentioned barrel.