This method is my FAVORITE way to Bounce In Place in Logic Pro X.
Bouncing in Place in Logic Pro 10.5 allows you to render one or more selected audio, software instrument, or Drummer tracks (including active plug-ins and automation on the tracks) to a new audio file.
With this small trick, you can make the BIP a perfect loop. This is achieved by adding a silenced piece of track at the end of the loop.
Simply chop any piece of audio and add it to the end of a 4, 8, or even 16 bar run. Then MUTE the CLIP by pressing "ctrl + m" on the keyboard. Finally, trim the audio clip to end exactly where you want your loop to end. Then BIP like normal.
NOTE: You cannot "include audio tail" for this to work properly.
The final Bounce In Place clip will be timed perfectly and allow you to loop immediately. From here, you can export the clip and add it to your loops library or your own sample packs.
Learn more about Jay Gemini's Sample Packs