Large POI between factory and my reloads

I did a quick range trip to check my scope before hunting. I had zeroed the scope using my reloads. Since I only had a few loaded up, I tried some factory ammo first, and did not even put a hole in the 2' x 3' paper at 100 yards. Switched to the reloads and got a 3" group, just
off a front rest.
Is such a difference unusual?? I am puzzled but only have 3 centerfire rifles so not much of a sample.
Savage 99, .308 win caliber.
Factory ammo. Federal powershock 180gr soft point
Reloads. 36.5gr h335
Lake City cases trimmed 2.005"
Speer 165gr hot cor soft point
2.700 OAL
CCI LR primer

Not unusual.

Thanks.

Agreed. Not unusual at all.

In fact I would say a likely event. Especially considering the bullet difference and likely velo diff too.

Agreed as well.

Yup

If you asked me before you shot these with the data you gave, I'd say you would have a large POI difference. The main issue is the velocity with your reloads. You are running a below minimum load with H335 and a 165 grain bullet (not sure why). You're probably around 2200-2300 fps, which is very slow. Then you do have a different bullet, which should only cause a small difference.

I have read savage 99's can be problematic when used with modern full power loads.

Correct, you can't run full power 308 Win ammo in them. But 36.5 grain of H335 is a very light load.

My old Lyman manual gives a starting load of 43.0, max 47.5. NRA manual says reduce about 3 grains for thicker military cases.
I started at 41 grains, and had trouble extracting. I ended up tapping out the case with a cleaning rod. So I pulled those loads, I had 3 cases loaded from 41 to 45 gr in 1/2 gr increments, and started again at 35-38gr.
36.5 gave me good accuracy over the iron sights, so I stopped there, since where I hunt 100 yards will be a long shot.
Dropping the OAL from 2.800 to 2.700 seemed to make feeding easier.
Only reason I can think of is that I might have a tight barrel. I have not slugged it, might do so after deer season.