19 ft lbs is a lot for the 34 series action. If you got it that high it would probably be harsh and not pleasant to shoot.The JM spring may give you power equal to the factory spring or it may be slightly lower. The Diana factory springs were notorious for being over stressed and brittle. They developed high power but at a price, usually a shorter life span. JM makes his springs to last longer than the factory, and usually gives up some power to do so. From his web site:
NEW- GRT. RWS-Diana 34,36,38,40,45,46, 300 kit
View Product Images NEW- GRT. RWS-Diana 34,36,38,40,45,46, 300 kit
Price: $69.00 Availability: in stock Prod. Code: GRT34
New for 2008
Includes custom guides,flange washer, spring and sample tar.
Moderate high power and vibration free.
Not for steel trigger old RWS45
Uses Hardened-polished rear washer.
So it's moderate hi power to what? The factory Spring? So I think you might loose a little fps but gain the smoothness, lack of vibration and longevity.
If you want a legit 19ft lbs or so, look at a different gun M350 M48 Gamo Hunter Extreme (1250) the TF 89/AR1000 RX-2 etc. They are out there but may(do) cost more money. 19 ft lbs is approx 780 fps @ the muzzle w/ a 14.3 grain pellet. That's more than most spring rifles can do. I'm not talking about "advertised" or diesling/detonation boosted numbers either. Real world over a chronograph 780 fps. The M34 is a great design from Diana that's been around for more than 20 years, but trying to get those numbers out of it IMHO is pushing it.
V/R
Nathan