Here's the specs on Diana 240 factory main spring

[airsenal]

DIAP-240-23 18.3 mm OD x 2.7 mm W x 200 mm L (29 coils) or 0.720" x 0.106" x 7.874". Looks like I won't use this as a back up or replacement spring in my Diana LP8.
I'd noticed reading up on the Diana 240 that it isn't producing the power I recall in Diana 24s a dozen or more years ago. No doubt a main spring out of one of those would be just right for a LP8. Got to keep the magnum a magnum. Probably a JM Merlin XL cut to size would deliver too. Those with Diana 240s could bring them back to the older 24 power level too. Puzzling why Diana took the 6ish FPE down to 4ish FPE. IMO going up to high 7s to 8ish FPE would have been better for sales and maybe TO6 trigger too to be a R7/HW30s challenger.