Autofit Column Range By Column Number

I've been trying various syntax for an hour now and I cannot figure out how to reference a range of complete columns by column number.

I know this works

Code:
Worksheets(strWS).Columns("B:I").EntireColumn.AutoFit

But the number of columns is dynamic, so I don't know which one is the end. So I have the column number but cannot figure out how to reference the column range by number. I have tried versions of the code below but they all give different errors. This one is Run-time error 1004 Application-defined or object-defined error.

Code:
Worksheets(strWS).Columns(Cells(1, 2), Cells(1, lngLastCol)).EntireColumn.AutoFit

I am pretty sure I am close but the referencing is the issue. I can find all sorts of referencing by letter but not number. I've tried

Code:
Worksheets(strWS).Columns(Columns(2), Columns(lngLastCol)).EntireColumn.AutoFit
but I get the same error.