what piston is best for feet per second to about 350 fps to 400?

Question

or is that no possible?

Answer 1

You mean pistol?

Most firearm pistols exceed 400 fps

Or if you're talking about airsoft

Use a gas pistol

Answer 2

If you're talking about air guns, it's not the piston that
makes the power, it's the piston seal and spring
that makes the power. Not all seals and springs are equal
either. Stock factory seals and springs are usually the
crappiest ones. It also depends on the model and make of
the gun it's self. Lower end guns such as Crosman, Gamo,
and some Beemans.(Beeman is the distributor, not the manufacturer. The GH, GS, SS models of Beeman are actually
made in Spain, some Crosmans are Chinese, and Gamo is
Spanish also. The top of the line models of Beeman are the
R series, these are made by Weihrauch, in Germany. These are
top of the line air guns, they run from $200, lower end, up to $750
for the top end.) Usually it takes a good tune to the gun to increase the power. This means, full strip down, deburr rough spots in piston chamber, degrease everything, change seal, spring, relube with proper moly. So, just changing the seal won't
do nothing to increase power. And like I said before, it depends on
what kind of gun you have, because 350-400 fps isn't much power increase, my least powered gun shoots at 775 fps, and that's a Co2 gun.

Answer 3

I would go with the bluish titamium pistons, and get some new heads for it, and you could upgrade your spring to 120 percent, that would increase power.

Answer 4

Well there's the agm mp40 AEG, but that's more like 120$

Answer 5

a pellet gun