A single engine aircraft pilot experienced a NMAC with no traffic reported as he entered the DCA SFRA at the BRV Gate and while talking with ATC about avoiding R-6608.

Narrative

Returning to Manassas entered DC SFRA at BRV gate. Potomac advised I go to Barin D then Manassas to avoid R6608 A; B; and C. I had planned to do this anyway; while daylight and clear; sun was low and behind clouds; so nothing was sunlit. I was approaching the several tail antenna towers about 6 NM southeast of Manassas airport and proceeding from Barin D to the airport; when; too late; I saw opposite-direction traffic at about 10 to 10:30 o'clock; same altitude about 500 FT away. In the quick glimpse I caught I saw a high wing southeast with gear retracted; seemed to be white with wavy (?) red trim. I believe I had just been handed off to Manassas Tower from Potomac Approach. I had not yet been able to establish communication with Tower. I'm beginning to realize what a dangerous area this is. We are sandwiched horizontally by R6608 and vertically between the Class B floor and the antenna towers. And some of us are talking to Manassas Tower and some to Potomac Approach and some in between. I filed a report for a near miss in the same area. What will I do to try to avoid a mid-air collision near Barin D? I will still approach Manassas via Barin D; but I will continue north 4 NM more before I turn toward Manassas. Then I go lower and will not be directly opposite traffic departing Manassas for Barin D. Could you please advise Potomac Approach that there will be a mid-air at Barin Dif they don't coordinate better with Manassas Tower.