Most powerful spring pistol?

Definitely not a $500 HW Silver Star. What a twangy disappointing item. 
I believe one of the Hatsan pistol/carbine sized ones hold that title; but if you want nice, get an older Diana springer pistol. JMO and I’m no pistol man.

Most powerful does not often equal "best" in the Airgun world. Tell us about how and what you want shoot. Accuracy is king in the Airgun world. Often the "most powerful" is accuracy pitiful.

What caliber?

What target?

What optic?

These will help us guide you to Airgun bliss(tm)

HW45/P1

Awesome guns and a brilliant design.

I just bought the Beeman "P1", same basic gun as the HW45 (as noted above).

Installed a red dot sight, did a little trigger adjustment. Oil on all pivot points, ready to go.

More accurate than I am, easy to shoot (offhand). The frame is much like a Colt 1911, .45. Can use 1911 grips if you want to change them. I'm looking for different grips now.

Mike

HW45 always has been the top dog ... appears to still be that way

The American classic is not a Springer but with fairly inexpensive and relatively simple mods will produce a pistol that will deliver you the 600+ fps in .22 Cal. And is very accurate also.

My Beeman P1 is powerful,butt I think my RWS Diana P5magnum is more so,plus costs less.

well it isn't the Diana 5g mag or P5 and it is a harsh shooting pistol

the Diana LP8 has better performance, has a trigger that need LOTS of work but can be improved to almost match quality

the Hatsan 125 have good performance but I will say they are a bit crude but cheap compared to others

the old BSA Scorpion has good power and quality but hard to find and sometimes not cheap

there is the Browning 800, it has power but it is harsh at firing, has a recoil system like the Hatsan but I wouldn't pay more then 50 buck and then find a place to store it because you won't shot it

the Weihrauch HW 45 and all the other models either Beeman or HW are a fine pistol, not cheap, but there are some that love them and other that don't care for them

the HW45 if far easier to shoot in .20 and .22 because the felt recoil diminishes as the caliber goes up

a Zoraki HP-01 would be a better choice but not a spring pistol hard to impossible to find new any more but a pistol that should be owned by any air pistol shooter

so I own 1 or more of all these pistols except the BSA

also a IZH 46m would have a good power rating but not a spring pistol

Take a look at the Browning 800/Hatsan Supercharger

I can't imagine it's going to be the most accurate regardless of the choice.

My dad bought me a BSA Scorpion when I was a kid. That thing was the most powerful spring pistol I ever owned. It was the 80's and I could never find a pistol scope to hold up to its recoil. When it finally ate one of my dads Leupolds, it had to go.

I have the hatsan 25 supercharger vortex .22, it's listed as a 600 fps pistol, it was to hard to cock so i let some air out of the gaspiston so now its very nice and have good accurasy, loves jsb 18,13gr and air arms 16gr

My Beeman .177 cal. P1 shoots JSB 7.87 pellets at 510 fps., but my Air Max .177 cal Gen 1 pistol shoots them at 661 fps. That's the difference between a springer and PCP, but 510 out of a springer is pretty respectable.

Diana LP8. 
not as powerful as the weirauch 45, but more user friendly in my opinion. And the metal frame and build.......... very impressive. 

Tom Gaylord got an honest 700 FPS with the Diana/RWS LP8 Magnum. I have one , and they are fast , and accurate. They deserve a scope. I have the BSA Edge 2x7x32 scope on my LP8 , and have had no problems , and over 150 shots taken. I had two other spring powered Diana pistols which I didn't like nearly as much. They now have a shoulder stocked carbine model , but that is not a pistol. Truth being , I like my Beeman P1 much better. Smaller , but smoother , more accurate , easier to cock , and plenty fast. Dr. Robert Beeman's team developed a winner when they sent the blue prints to Weihrauch back in the early 1980's. Don't overlook the Crosman MK1 , which can be increased in power and accuracy by Mac1 in the Los Angeles area.

While waiting for the research on the most powerful spring pistol, I recommend buying a $20 Beeman P17 to practice with. It's unusually accurate for a sub $100 pistol and makes a great grab and go back yard gun.

I will jump on the HW 45 / P1 / P11 bandwagon here. It is not cheap, may not be the springer pistol with the absolute most FPS these days, and takes practice to shoot well. But it combines plenty of power with excellent build quality, accuracy, a reasonably compact size and weight, good sights, and a great trigger.

I bought one soon after they first came out in the 80’s. It still looks and works like new, and in all these years I’ve never met a springer sporter pistol I like better.

My hatsan supercharger slings 14 grain ammo at 580 fps