Run-Time Error '6' overflow (copy range from closed workbook) - vba

Question

I have the below code placed on my active workbook which copy's data from a closed workbook. It works fine and very fast but i can only copy up to 8 columns if I select more than that I get a
run-time error 6 - Overflow
Code:
Sub Get_Data()
Dim RngToCopy As Range
Dim wkbk As Workbook
Dim DestCell As Range
Dim myFileNames As Variant
Dim iCtr As Long
Dim testStr As String
Set DestCell = ThisWorkbook.Worksheets(1).Range("a1")
myFileNames = Array("C:\my documents\excel\book1.xlsm") ' i could add more workbooks to copy from and append on current worksheet
For iCtr = LBound(myFileNames) To UBound(myFileNames)
testStr = ""
On Error Resume Next
testStr = Dir(myFileNames(iCtr))
On Error GoTo 0
If testStr = "" Then
MsgBox myFileNames(iCtr) & " doesn't exist!"
Else
Set wkbk = Workbooks.Open(Filename:=myFileNames(iCtr))
With wkbk.Worksheets(1)
Set RngToCopy = .Range("a2:r2", _
.Cells(.Rows.Count, "A").End(xlUp))
End With
DestCell.Resize(RngToCopy.Rows.Count, _
RngToCopy.Columns.Count).Value _
= RngToCopy.Value
Set DestCell = DestCell.Offset(RngToCopy.Rows.Count, 0)
wkbk.Close savechanges:=False
End If
Next iCtr
End Sub
when I debug the line that it goes to is: where am I going wrong :(
DestCell.Resize(RngToCopy.Rows.Count, _
RngToCopy.Columns.Count).Value _
= RngToCopy.Value
the source workbook is a big file with a lot of data, I tried most of the suggestions when I researched on the error but no luck.
if it helps workbook contains 18 columns and 300k+ rows

Answer 1

Try a different approach, use Copy >> PasteSpecial (values only) :
' 1st: set copy range
With wkbk.Worksheets(1)
Set RngToCopy = .Range("A2:R2", .Cells(.Rows.Count, "A").End(xlUp))
End With
' 2nd: set destination range start position
Set DestCell = DestCell.Offset(RngToCopy.Rows.Count, 0)
' 3rd: use copy>>paste special (values only)
RngToCopy.Copy
DestCell.PasteSpecial xlPasteValues