When I do this (in batches) I wonder if the selection criteria (i.e. "like 'SIC%'" in your case) takes time on each iteration of the loop.

I get all the clustered index keys into a #temporary table, ordered by those keys, with an IDENTTIY column, and then delete in batches based on ranges of the ID. Something like this:

SELECT IDENTITY(int, 1, 1) AS MyID, ClustKey1, ClustKey2, ...

INTO #TEMP

FROM F_POLICY_TRANSACTION

WHERE [POLICY_TRANSACTION_BKEY] like 'SIC%'

ORDER BY ClustKey1, ClustKey2, ...

DECLARE@intLoop int = 1

WHILE 1 = 1

BEGIN

DELETE D

FROM #TEMP AS T

JOIN F_POLICY_TRANSACTION AS D

ON D.ClustKey1 = T.ClustKey1

AND D.ClustKey2 = T.ClustKey2

AND ...

WHERE T.ID BETWEEN @intLoop AND @intLoop + 50000

IF @@ROWCOUNT < 50000 BREAK;

SELECT @intLoop = @intLoop + 50000

END

I'd be interested to hear if that is any more efficient for you.