Having a bit of an issue finding a sweet spot with my two .454’s. Either the ballistic tables are dead wrong or there is a loose nut behind the trigger.

Had both of my guns zeroed at 25yds with my milder 250gr loads that were running around 1300fps. When I switched to my hunting loads (240gr running around 1800fps) I was completely missing a 8” gong at 50yds. I expected a 1” or 2” poi shift but damn, this isn’t inspiring confidence to bring on a hunt.

Any thoughts, experiences here? TIA

Where are the rounds going?

High left.  You could be flinching.

I've got the pistol in a caldwell pistol rest. Had a hard time seeing where the rounds went, no splash etc. I really think the rounds are high though. I'm just miffed that they can be that far off at 50yds vs 25. Back to the range tomorrow to get a handle on it....

Q1 Jacketed or cast bullet?

Q2 Why do you need 1800 FPS are you hunting birds or large game?

Q3 Are you shooting open sights or an optic?

Q4 Have you checked the sights or optics for being loose?

Jacketed xtp mags. Hunting deer and hogs ~100yds max. Pistols are pictures below.

Your rounds are almost certainly shooting to a very different point of impact.  That big of velocity difference will make a pretty big difference in point of impact due to a handgun moving different amounts under different recoil impulses.  My competition load in my S&W 610 was a 180gr bullet going ~950fps.  My Hunting load is a 200gr bullet going 1250fps.  When I got ready for hunting season the hotter hunting loads where probably 6-8 inches different at 35 yards compared to my competition load.  Start with your hunting load at 25 yards.  Make required sight adjustments and then move back to fifty.

Seems like a huge change to me. I have a .460 and while I don't reload, I can shoot multiple calibers.   At 25 yards a .45LC hits within a 1/2" of a full power .460 load.

:edit:   At 50 yards and up I don't shoot the other calibersin the .460 but bullet weight differences haven't amounted to inches either. I wonder if you're not getting some kind of jump off your rest.

I could be wrong, but maybe 25 yards isn't a good range for you to zero with your setup. The distance from center of bore to your sight makes a massive difference if you're using a ballistic calculator (on hornadys site for example). Maybe recheck your measurements, and if that doesn't work just shoot and experiment more! Also as others have said, jerking the trigger makes a huge difference at 50 yards then at 25. I can peg a 2 liter bottle everytime at 50 yards with my 45 colt but if i jerk that trigger i know it cause I'm a foot off or more!

Also, if you're using a different powder for your hunting load that dwell time difference can make a huge poi shift, especially if it's a slower burning powder you'll hit a lot higher than you'd think!

That’s an interesting thought on the powders. I’m using Unique, w296 and IMR4227. I think you may be onto something here. I’ve measured the sight height and entered that variable. Thanks everyone.

There are a few diferent factors that affect point of impact versus point of aim with a handgun, as the load changes:

1) Pistols recoil to a much more noticeable extent than rifles.  In practical terms, due to the light weight of the pistol, the muzzle rises significantly before the bullet ever leaves the barrel. That changes the angle of departure.  In turn how much the muzzle rises with one load compared to another affects the point of aim.  Generally speaking, lighter and faster = lower.

2) One variable is bullet weight.   Most .38 Specials and .357 Magnums, for example, have sights regulated for a 158 gr bullet.  If your .357 shoots to point of aim, for example, at 10 yards, and you shoot a 125 gr load instead, you'll find it impacts a couple inches low even at that short range. That's due in part to the higher velocity of the bullet leaving the bore sooner, before the departure angle can increase as much, and due in part to lighter bullets having less recoil than heavier bullets, when everything else is basically equal.

3) With bullets of the same weight, velocity makes a big difference.  Higher velocity does mean less time in the barrel, but it also means much higher recoil when the differences are large, such as moving from 1300 fps to 1800 fps.  Here the effects are not as clear, as faster equals lower, but there's also an inflection point where significant increases in recoil and more muzzle displacement start to offset and reduce the effects of the faster bullet.

4) The powder charge makes a difference as well.    For example you might be using around 17 grains of Win 296 in a .45 colt case to get 1300 fps compared to just north of 37 grains of Win 296 is a .454 case to get 1800 fps with similar bullets.  Even if the bullet weight is identical, that extra 20 grains of powder still has mass even after it burns, and unlike the bullet, that mass leaves the barrel at about 3 times the muzzle velocity of the bullet.  That more or less equates to a 60 grain increase in bullet weight.  Faster burning powders that require less powder produce less recoil for this reason, even when the bullet velocity is the same or slightly higher.   You'll see this effect a lot with powders like Unique in some of the smaller magnum handgun rounds.

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Regardless of the cause, it'll be what it is.  You'll need to back up to somewhere between 10 and 25 yards and zero with that load, then either increase the range in increments to ensure you're still on the paper, or use a ballistic program, in putting the known velocity, and sight height (distance from center of the bore to top of the blade, or center of the scope).  If you're guestimating the velocity, you'll still be on the paper but will need to make more adjustment to your final zero.

This approach ill work because the load is the same, and thus the recoil and muzzle rise before the bullet departs is the same, so the differences will once again just be due to the external ballistics.

Thank you! That all makes perfect sense. I’ve got it zeroed now, But I’m still struggling to find the right powder combo for the 240gr in the 454.

This cartridge seems a bit more finicky than the .357 & .44mag loads I used to make years ago. It almost didn’t matter what combo I used in these, they all shot well for me, not so here.

FWIW I’m trying to replicate the Hornady factory load in 240gr. It actually shoots great! I don’t think they are using ~H110/W296 in their load, or if they are it’s flash suppressed. I recently grabbed a pound of AA#9 and will test that with the 240’s.

I've experienced a 6"+ POI difference at 50yds with my .45 Colt Redhawk when I switch from my 255gr plinking loads to full power 340gr bear defense loads.
Higher bullet weight and power  has higher point of impact.

IMO, 4227 will be too slow a powder for your light 240gr projectiles.  Try a faster powder.   H110 will work if you want magnum velocity and blast.  For a milder load, try something else.