"It doesn't work that way, there is a reason why the ammo is cheaper. Not all ammo is the same. Practice with what you are going to carry all the time.
As for money, I guess it would be cheaper to practice with your SD ammo then a $200,000 medical & surgical bill or a $10,000 funeral.
Stay safe as to shooting straight, use you SD Ammo.
Jim"
OK I have to disagree with this, sorry Jim. Now I will agree that not all ammo is the same, for instance I certainly would not expect Tula to perform anywhere as good as American Eagle when it comes to practice ammo. But I have no issues what so ever using AE as my regular practice ammo and then running Federal HST for SD. Lets face it box for box AE is a lot more affordable per case than the HST. The only real importance when it comes to shooting SD ammo is to shoot enough to ensure it will run in the gun, and with modern manufacturing of both guns and ammunition it is not to difficult to achieve reliability. Providing you are using a quality gun like Glock, Sig, S&W and quality ammunition like Federal HST, Winchester Ranger or Speer Gold Dot.
Just for fun lets do some quick comparisons:
AE 40 S&W 180g FMJ has a velocity of about 1000FPS and a muzzle energy of 400 ft.lbs.
Federal 40 S&W HST 180g JHP has a velocity of about 1010fps and a muzzle energy of 408 ft.lbs.
A whopping 8ft.lbs. difference, oh no!
AE 9mm 124g FMJ has a velocity of about 1150fps and a muzzle energy of 364 ft.lbs.
Federal HST 124g JHP +P has a velocity of about 1200fps and a muzzle energy of about 396ft.lbs. of energy.
Now you have a little bit of spread of 32ft.lbs. but still not enough to make a noticeable difference.
This brings me to my next point. Unless you are running real extreme differences in power between your practice and SD ammunition you will not notice it. Under the stress of a lethal force encounter there are physiological responses of the body. One of those is the loss of fine motor skills which the perception of recoil will fall under. The body instantly goes into survival mode and the senses that the brain feels is most important to the bodies survival are what get heightened. This is where the time distortion, auditory exclusion and tunnel vision come into effect. Tunnel vision is a result of visual acuity to precisely see and react to a threat. Time distortion is a result of the brain working at an accelerated rate to solve the life threatening problem at hand which intern makes everything seem to be moving in slow motion. Auditory exclusion is result again of the brain saying that is not necessary at this very moment so it shuts it off until needed, hence when asked people say my gun sounded like a BB gun and I thought it was malfunctioning(also ties in to you won’t feel the recoil).
To further exemplify the lack of perception of recoil I have been fortunate enough to train and have many conversations with Rob Leatham. He has told me that even with all of his extensive shooting experience and 100,000’s or rounds fired every year even he can’t tell the difference in power of ammo during matches, which at this point in his shooting career causes him very little stress. So if a person that shoots as much as this man can’t tell the difference between loads in a low stress situation what is the likelihood of a novice shooter noticing the difference in recoil in a high stress situation?