What amount of FPE is needed to knock down targets in field target competition

[rws45user]

What amount of FPE is needed to knock down targets. I have a Izh 46m pistol I'm going to put in a rifle stock . Does anyone know if this gun has the power to knock down the maximum distance target . And How do you figure  this out . If this is not the correct place to ask this question will someone direct me to the right  place . Thanks . 

[SciGuy]

Targets are set to fall with 4 FPE at the target.  An Izzy will not have enough power left at 55 yards to drop the target.  Generally, 8FPE at the muzzle would be the minimum and 10 would be a better minimum. 

[rws45user]

Thanks sciguy  I just put in some  numbers in my Hawke chair gun  and it looks like  if I use the exterminator fac 15 grain pellets I would have 4.10 fpe at 55 yards . with the guns fps of 427 .

[Motorhead]

Thanks sciguy  I just put in some  numbers in my Hawke chair gun  and it looks like with a 5 grain pellet at 55 yards will be at 1.2 fpe .But if  I use a 20 grain pellet I would have 4.2 fpe with a 17 inch drop . lol

Alloy pellets are too light and by many FT clubs not allowed either.  They damage targets and ricochet potential is much greater.
8-10 Ft Lbs at muzzle with @ 8 grain weight LEAD pellets is about as low as is practical to get consistent target knock down when struck IMO   

[rws45user]

Thanks for the help