Don't get it. In a project at 125, to an acoustic guitar rythm clip, I recorded a new track of a hand-percussive beat on the backside of my guitar,,and in good time. Just 2 or 3 bars worth. When I click to convert this into a loop, or put it into loop construction view, it is now BMP 165 ( as its "original BMP") and not in sync at all! Huh? So what am I doing stupid and wrong ? THANKS!

If you recorded the taps to the metronome you should be good.
Select your taps in the time line and count out the beats (4 beats per measure / 3 measures= 12 beats)
Open up the Inspector and input the beats. this gives sonar a better chance to calculate.
 
your other option is to use the Loop construction view. which can work flawless for small loops like this.

I think I'm getting this down now ...thanks

That loop construction has me lost.   Ive never managed to take a clip (lets say a small loop i downloaded) and edit it successfully. 

Agentcalm
That loop construction has me lost.   Ive never managed to take a clip (lets say a small loop i downloaded) and edit it successfully. 

Your best bet is to import the clip, Set the projects BPM to as close as possible to the clips tempo
(Use Autosnap or Tap tempo to find the clips tempo) Once the project tempo is close to the clips tempo Loop construction and/or Groove clips are much easier to work with.
 
Bite off small sections at a time, don't try to create a 20 measure/80 beat Loop.
Start small= 2 measure/8 beats. and use the inspector if needed to adjust the beats per clip.
Then you'll be on your way to being a RockStar

https://youtu.be/4nHOmGPeVc8

I did find it better to first make the clip sound just like it should in track view, and with the looping activated and then split off/ erase any left and right sections that remain, then put this in track view, give another listen; just in the Construction view (not with the project playing), then hit "Loop" button. The other neat thing I discovered was it saves this into the Loops folder that appears in the browser.