at what point does this rnd go subsonic..

[slim rem 7]

 im shooting the velocitor.. its no contest rnd but very hard hitting at 100 yrds
 1088 i believe with adequate accuracy..the rnd itself seems to be an very destructive rnd even at low velocity..at low velocity it goes from an high penetrating an expanding rnd to one that penetrates less but what ever is penetrated is really messed up.. whats bad is the rnd just cant be depended on so far out 140 yrds or so..this using marlin 60 and cz 452..
 so with an muzzle vel of 1435 i think.. an 100 yrd vel.. of 1088 ..can someone with more knowhow tell me when the rnd passes below sonic speeds..thats the only reason i can figure for the change in the rnd way out there accuracy..at present a 150 yrd shot can t be counted on to stay on a sheet of notebook paper for 5 rnds..
to bad as what ever it hits out there, looks like a sledge hammer hit it.. ..id like to get it so i can controll it out there an then i ll have my all purpose gun an rnd .. any help appreciated ..slim..

[MikeC]

Speed of sound is about 1100 feet/second. Note that to be exact you have to take into account the temperature etc. There are calculators online for example:
http://www.sengpielaudio.com/calculator-speedsound.htm

[slim rem 7]

 well according to that the rnd has went subsonic just before the 100 yrds..
 thats why the 100 yrd group while, satisfactory, is not what i expected from the rnd, as its 50 yrd group, is right there with my best group ammo.i gotta figure how to use it,, as its way harder hitting than any 22 lr rnd ive ever tried..its just short of the magnum..i ll try an make some kinda adjustment somewhere so i can overcome this
problem.. it may just take making sure im no more than a hundred yrds ..i guess i can live with that..thanks matt.

[ironglow]

 Using CCIs own figures, it should drop below 1100 fps, just before 100 yards.

  http://www.cci-ammunition.com/ballistics/detail.aspx?loadNo=0047