Toilet Flange Inside 4" Pipe

I removed the tile from one of my bathrooms and found the old toilet flange was a good 1" above the concrete slab. I have an Oatey Fast Set PVC flange that goes inside the 4" pipe. After a hour of carefully chiseling out the old flange (that was also an inside pipe flange) I am finding that the flange does not go fully into the pipe. At first I thought this is like dry fitting and there would be a interference fit. However, this offset when dry is like 2" and not the normal 1/2" or 3/4" that I would expect. The 4" pipe has been trimmed so that it fits flush with the slab. The newly installed tile is 1/2" thick. How do I ensure that the flange will go all the way flush with the floor? I can find no information on any offset vs dry fitting length.

I did sand the inside the 4" pipe after removing the old flange and I can certainly sand some more if that is the solution. I can also sand the fitting a bit as well. Thanks in Advance!

Can you show a pic of what your using and what your trying to push it out n?????? Thanks

just to be sure of what we are discussing
you have a offset closet collar? or a regular closet collar?
offset pictured

from the back wall. what is the measurement to the center of the 4'' pipe?

is it 10'' or 11'' or 12'' ?

Give me a bit to get a picture as my phone was dead. This is a straight flange NOT an offset flange. The offset I was referring to was when you dry fit PVC, it will not go all the way in due to the interference fit. This is the flange I have...

So here are some pictures. I found one website that showed an "inside" pipe fitting going all the way into the pipe as a dry fit so that is why I am a bit concerned. I can sand down the fitting some. I also have an inside pipe cutter and could remove some more of the pipe but given that it is already flush the slab I would prefer not to do that.

there are 2 different types of flanges
one has a lip the other does not- see image-
if your flange has a lip, the top of the pipe needs to be 1/4'' below top of finished floor
if no lip, the flange will sit all the way down

i stomp on them, my helper uses a 2x4 and hammer
glue the pipe and the fitting, orient the bolt holes
then step on it , stomp it down all the way flush with he floor

You could switch to a flange that goes inside the drain, but seals against it with rubber seals, not a solvent weld.
That way you are not totally forked if you glue it, then quickly stomp on it, and it still ends up high, or you stomp on it and you break a connection down below.

For example.

Depending on how well the pipes are supported under the floor, if you do the solvent weld and get the flange all the way down flush to the floor, the pipes below might have been flexed down, and when you stop pushing they might return to their original position and push the flange up somewhat, and now it is glued in like that, sitting high.