16 inch 44 mag. Go to the range to zero it. At 25 yards, doesn't even seem to be on the paper. Adjusted for elevation, nothing. Shooting ppu 44 mag 240gr JHP. I aim way left and think I see an impact. I then switch to 240gr lead 44spl Winchester, and it's poa/poi. No windage or elevation needed. I'm thinking it has to be the Prvi 44 mag. I'll try something else next time, but I'm open to thoughts. Shots were off a bag, supported, and off hand all at 25 yards.

I did that, shift was windage. Which is why I'm confused.

Rossi uses a 1-30" twist in all its Model 92s regardless of caliber.  I have no idea why but it means you have to push the longer, heavier bullets in .45 Colt and .44 Magnum reasonably fast to get them to adequately stabilize.  

If the .44 Special ammo is a light to mid range load (by .44 Special standards), it may not stabilize properly and accuracy can be very poor.

For comparison purposes:

Originally, Winchester  used 1-38" twist on the Model 1892 in .44-40 way back in the day - but bullet weight was only 200 grains  in the .44-40-200 at 1245 fps, and it was comparatively short.  Remington started selling 217 gr ammo at 1,190 fps and it was also fairly short.  Winchester currently sells a cowboy load in .44-40 weighing 225 grs at only 750 fps, and it's much better suited to faster twist barrels.  

Ruger continued the Winchester trend and used 1-38" in its .44 Mag semi-auto carbine as well - but it was intended for full power 240 gr ammo, so it still worked well.

The Henry Big Boy; Marlin 336, Marlin 1894; Rem 788,  Win 94, and Browning 92 also used the 1-38" twist and are better suited to bullets of 240 grains or less with fairly stout loads.  

Ruger switched to 1-20" on its Model 96 lever action, and T/C used the same twist in its carbine, and Armi-Sport also uses 1-20" in its Winchester Model 1892 replicas.  Overall, 1-20" is a good choice for lighter "cowboy" loads, lighter loads with heavier bullets, or for really heavy bullets in the 270-300 grain range.

My experience with 1-38 twist in mid range loads wasn't pretty.  I noted that if I shot a 210 gr SWC (Lyman 429215) at around 1000 fps I got ok accuracy at 25 yards but it would not even be on the target backer at 100 yards.      

1-26" is probably ideal all things considered, and that ironically enough splits the difference between the 1-20"/1-22" options and the 1-30" twist in the Rossi.

Where the slow twist offers a potential advantage is if you are shooting traditional black powder loads with light bullets (200 gr or less) - emulating the .44-40.  The slower twist isn't really an impediment to accuracy with those bullets and velocities, and the slower twist helps minimize black powder fouling.  

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In any event, you'll probably find if you keep the velocity up, accuracy will be good. If you go with a light "cowboy" load in .44 Mag, stay with 200-205 gr bullets and keep the muzzle velocity at 1000 fps or higher.

I had no accuracy issue with 44 sp. it was dead on poa/poi. It was the mag that was way off.

Try some better ammo.  I've had serious issues with Privi before.  Was it the stuff Academy sells?

I'm hoping its this. Seems likely given the circumstances.

52, thanks for the good read. This really opened my eyes as to why I was having issues with my Rossi 16" carbine in 44mag and using cheap under powered 240 grain ammo. I swear the thing was Key holing at 20 yards.

Lever guns can be fussy about ammo.

They are also sensitive to bullet diameter.   I use a .433 bullet in my 44 Magnum Marlin 1894.   The identical bullet in .430 looks like a shotgun pattern and the .433 bullet shoots into an inch group at 50 yards.   these are lead alloy bullet handloads.

Over the years Rossi has had some issues with groove diameter.  Some need .433 diameter bullets to get any accuracy.  Also, after shooting jacketed, you need to really clean the bore of any gilding material left behind.  It will seriously impact accuracy when shooting cast.  If your twist is slower than 1:20, you need the lighter bullets.  1:38 can yield good accuracy if the bullet diameter fills the grooves but go no heavier than 200 grain pills...

Update:

Had the 92 out for a second round today, Brought several types of ammo. The prvi still no bueno. However, Hornady, Federal and CCI were right on target, along with all the 44spl I tried, including reloads. So in short, it was the ammo. The prvi is getting pulled, the bullets tossed and reloaded with some hardcast 240gr. Thanks all for the help.

DakotaFAL, so if I read this right, and I doubt I did. The larger bullet needs a little more powder behind it and the smaller bullets will do better in the 1-30 twist the Rossi has? I know there's a lot more to it then this? Just kind of a nut shell question.

I've found some Remington UMC 44 Mag that's 180 grain. I like this ammo. Regarding the 1-30 twist on the Rossi, would this smaller size bullet stabilize better then the larger 240 grain. I'm learning from your post, they are greatly appreciated here and over at Rossi Rifleman