Yes, dry fitting is restrictive and usually goes on about halfway. The glue process actually softens the plastic allowing the fitting to slip on completely.
Be sure the pipe is at or slightly below the needed height- determine this from the indent/hub of the flange. This is called the fitting make up
Also be sure the 90 below is well supported so it doesn't push down as you glue the flange on.
If the flange doesn't glue op good the first try- ABS is usually forgiving enough to pop it back off. But you got to do it quickly!
Be sure the pipe is at or slightly below the needed height- determine this from the indent/hub of the flange. This is called the fitting make up
Also be sure the 90 below is well supported so it doesn't push down as you glue the flange on.
If the flange doesn't glue op good the first try- ABS is usually forgiving enough to pop it back off. But you got to do it quickly!