diff --git a/Contest.pas b/Contest.pas
index dc1eeb7..d77be04 100644
--- a/Contest.pas
+++ b/Contest.pas
@@ -44,12 +44,14 @@   TContest = class
     procedure DropStation(id : integer); virtual; abstract;
     function GetCall(id : integer) : string; virtual; abstract;
     procedure GetExchange(id : integer; out station : TDxStation); virtual; abstract;
+    function GetRandomSerialNR: Integer; virtual;
     function GetStationInfo(const ACallsign : string) : string; virtual;
     function PickCallOnly : string;
 
     function OnSetMyCall(const AUserCallsign : string; out err : string) : boolean; virtual;
     function OnContestPrepareToStart(const AUserCallsign: string;
       const ASentExchange : string) : Boolean; virtual;
+    procedure SerialNrModeChanged; virtual;
     function IsFarnsworthAllowed : Boolean;
     function GetSentExchTypes(
       const AStationKind : TStationKind;
@@ -169,6 +171,15 @@ function TContest.IsFarnsworthAllowed : Boolean;
 end;
 
 
+{
+  Return a random serial number for the currently selected Serial NR mode
+  (a menu pick).
+}
+function TContest.GetRandomSerialNR: Integer;
+begin
+  Result := Ini.SerialNRSettings[Ini.SerialNR].GetNR;
+end;
+
 
 {
   GetStationInfo() returns station's DXCC information.
@@ -243,6 +254,20 @@ function TContest.OnContestPrepareToStart(const AUserCallsign: string;
 end;
 
 
+{
+  Called after
+  - 'Setup | Serial NR' menu pick
+  - 'Setup | Serial NR | Custom Range...' menu pick/modification
+
+  The base class implementation does nothing. Other derived classes can
+  update cached information based on the serial NR menu pick (e.g. CQ WPX).
+}
+procedure TContest.SerialNrModeChanged;
+begin
+  assert(RunMode <> rmStop);
+end;
+
+
 {
   Return sent dynamic exchange types for the given kind-of-station and callsign.
   AStationKind represents either the user's station (representing current
diff --git a/CqWpx.pas b/CqWpx.pas
index c69c2d8..8cf3ee8 100644
--- a/CqWpx.pas
+++ b/CqWpx.pas
@@ -20,7 +20,6 @@ TCqWpx = class(TContest)
   PrevSerialNRType : TSerialNRTypes;
   PrevRangeStr : String;
 
-  procedure InitSerialNRGen;
   function GetNR(const station : TDxStation) : integer;
 
 public
@@ -30,17 +29,17 @@ TCqWpx = class(TContest)
   function OnContestPrepareToStart(const AUserCallsign: string;
     const ASentExchange : string) : Boolean; override;
   function LoadCallHistory(const AUserCallsign : string) : boolean; override;
+  procedure SerialNrModeChanged; override;
+  procedure InitSerialNRGen;
 
   function PickStation(): integer; override;
   procedure DropStation(id : integer); override;
   function GetCall(id:integer): string; override;     // returns station callsign
   procedure GetExchange(id : integer; out station : TDxStation); override;
+  function GetRandomSerialNR: Integer; override;
 
   function getExch1(id:integer): string;    // returns RST (e.g. 5NN)
   function getExch2(id:integer): string;    // returns section info (e.g. 3)
-  {function getZone(id:integer): string;     // returns CQZone (e.g. 3)
-  function FindCallRec(out fdrec: TCqWpxCallRec; const ACall: string): Boolean;
-  }
   function GetStationInfo(const ACallsign: string) : string; override;
   function ExtractMultiplier(Qso: PQso) : string; override;
 end;
@@ -48,14 +47,40 @@ TCqWpx = class(TContest)
 implementation
 
 uses
-  SysUtils, Generics.Defaults, System.Math, {Ini,} Classes, ARRL;
+  SysUtils, Generics.Defaults, System.Math,
+  Main,           // for SetMySerialNR
+  Classes, ARRL;
 
 function TCqWpx.OnContestPrepareToStart(const AUserCallsign: string;
   const ASentExchange : string) : Boolean;
 begin
+  // Refresh Serial NR Generator before calling OnContestPrepareToStart
   InitSerialNRGen;
 
   Result := inherited OnContestPrepareToStart(AUserCallsign, ASentExchange);
+
+  // reload My Serial Number at start of contest. This allows Mid-Contest and
+  // End of Contest modes to set Tst.Me.NR with a realistic random number.
+  if Result then
+    MainForm.SetMySerialNR;
+end;
+
+
+{
+  Overriden for the CQ WPX Contest to allow regeneration of the SerialNRGen
+  tables (based on new Ini.SerialNR setting).
+
+  Called after
+  - 'Setup | Serial NR' menu pick
+  - 'Setup | Serial NR | Custom Range...' menu pick/modification
+
+  This can be called during a Run if the user selects a different
+  Serial NR distribution (e.g. Mid-Contest, End of Contest, etc.).
+}
+procedure TCqWpx.SerialNrModeChanged;
+begin
+  assert(RunMode <> rmStop);
+  InitSerialNRGen;
 end;
 
 
@@ -77,6 +102,8 @@ constructor TCqWpx.Create;
   inherited Create;
   CallLst := TCallList.Create;
   SerialNRGen := TSerialNRGen.Create;
+
+  InitSerialNRGen;
 end;
 
 
@@ -228,6 +255,12 @@ procedure TCqWpx.DropStation(id : integer);
 end;
 
 
+function TCqWpx.GetRandomSerialNR: Integer;
+begin
+  Result := Self.SerialNRGen.GetNR;
+end;
+
+
 // return status bar information string from DXCC data file.
 // the callsign, Entity and Continent are returned.
 // this string is used in MainForm.sbar.Caption (status bar).
@@ -271,12 +304,19 @@ procedure TCqWpx.GetExchange(id : integer; out station : TDxStation);
 end;
 
 
+{
+  Returns the serial number for a DX Station being worked.
+  For HST or Start-of-Contest serial NR modes, the serial number is based
+  on elapsed time and operator skill. For Mid-Contest and End-of-Contest
+  modes, the serial number returned will follow a distribution similar to
+  the a WPX Contest. See SerNRGen for more information.
+}
 function TCqWpx.GetNR(const station : TDxStation) : integer;
 begin
   if (RunMode = rmHST) or (Ini.SerialNR = snStartContest) then
     Result := station.Oper.GetNR  // Result = f(elapsed time, operator skill)
   else
-    Result := SerialNRGen.GetNR;
+    Result := GetRandomSerialNR;  // follows WPX distribution of serial NRs
 end;
 
 
@@ -291,6 +331,7 @@ function TCqWpx.getExch2(id:integer): string;    // returns serial number (e.g.
   Result := '1';
 end;
 
+
 end.
 
 
diff --git a/Ini.pas b/Ini.pas
index 84ae7c1..cb12430 100644
--- a/Ini.pas
+++ b/Ini.pas
@@ -57,6 +57,7 @@   TSerialNRSettings = record
     procedure Init(const Range: string; AMin, AMax: integer);
     function IsValid : boolean;
     function ParseSerialNR(const ValueStr : string; var Err : string) : Boolean;
+    function GetNR : integer;
   end;
 
   PSerialNRSettings = ^TSerialNRSettings;
@@ -514,6 +515,16 @@ function TSerialNRSettings.IsValid: Boolean;
 end;
 
 
+function TSerialNRSettings.GetNR : integer;
+begin
+  assert(IsValid);
+  if IsValid then
+    Result := MinVal + Random(MaxVal - MinVal)
+  else
+    Result := 1;
+end;
+
+
 function TSerialNRSettings.ParseSerialNR(
   const ValueStr : string;
   var Err : string) : Boolean;
diff --git a/Main.pas b/Main.pas
index 8026222..0001765 100644
--- a/Main.pas
+++ b/Main.pas
@@ -398,6 +398,7 @@   TMainForm = class(TForm)
     procedure Advance;
     procedure SetContest(AContestNum: TSimContest);
     procedure SetMyExchange(const AExchange: string);
+    procedure SetMySerialNR;
     procedure SetQsk(Value: boolean);
     procedure SetWpm(AWpm : integer);
     procedure SetMyCall(ACall: string);
@@ -1181,6 +1182,13 @@ procedure TMainForm.UpdateTitleBar;
 end;
 
 
+procedure TMainForm.SetMySerialNR;
+begin
+  assert(Tst.Me.SentExchTypes.Exch2 = etSerialNr);
+  SetMyExch2(Tst.Me.SentExchTypes.Exch2, Ini.UserExchange2[SimContest]);
+end;
+
+
 procedure TMainForm.SetMyCall(ACall: string);
 var
   err : string;
@@ -1310,16 +1318,23 @@ procedure TMainForm.SetMyExch1(const AExchType: TExchange1Type;
 procedure TMainForm.SetMyExch2(const AExchType: TExchange2Type;
   const Avalue: string);
 begin
+  assert(RunMode = rmStop);
   // Adding a contest: setup contest-specific exchange field 2
   case AExchType of
     etSerialNr:
       begin
+        var S : String := Avalue.Replace('T', '0', [rfReplaceAll])
+                                .Replace('O', '0', [rfReplaceAll])
+                                .Replace('N', '9', [rfReplaceAll]);
         Ini.UserExchange2[SimContest] := Avalue;
-        if not IsNum(Avalue) or (RunMode = rmHst) then
-          Tst.Me.Nr := 1
+        if SimContest = scHST then
+          Tst.Me.NR := 1
+        else if S.Contains('#') and (SerialNR in [snMidContest, snEndContest]) then
+          Tst.Me.NR := 1 + (Tst.GetRandomSerialNR div 10) * 10
+        else if IsNum(S) then
+          Tst.Me.Nr := S.ToInteger
         else
-          Tst.Me.Nr := StrToInt(Avalue);
-
+          Tst.Me.Nr := 1;
         if BDebugExchSettings then Edit3.Text := IntToStr(Tst.Me.Nr);  // testing only
       end;
     etGenericField, etNaQpExch2, etNaQpNonNaExch2:
@@ -2344,12 +2359,15 @@ procedure TMainForm.UpdSerialNR(V: integer);
   if not Ini.SerialNRSettings[snt].IsValid then
     snt := snStartContest;
 
-  //Ini.NRDigits := nrd;
   Ini.SerialNR := snt;
   SerialNRSet1.Checked := snt = snStartContest;
   SerialNRSet2.Checked := snt = snMidContest;
   SerialNRSet3.Checked := snt = snEndContest;
   SerialNRCustomRange.Checked := snt = snCustomRange;
+
+  // update contest-specific settings/caches (e.g. SerialNR Generator for CQ Wpx)
+  if not (RunMode in [rmStop, rmHST]) then
+    Tst.SerialNrModeChanged;
 end;