[JimQuiz]

FWIW, there are probably very few guitarists that didn’t struggle, a lot, with the G<>C, C<>D, and G<>D transitions. Not to mention the F chord and all it’s transitions.

All the suggestions above are great. Use your metronome, always (I believe). Do the finger push-ups mentioned above. Start with, say, C shape. Form the chord, strum, lightly lift the fingers without removing them from string, apply pressure, strum. Sound good? No, adjust your fingers and repeat. I usually do 50-100 reps like this at 30 BPM until I feel like I am mostly getting it. Now, up the challenge, repeat above but slightly lift your fingers off the strings (just enough to lose touch, 1/4″) Good? Yes, repeat straightening fingers between each strum. Good? Yes, repeat taking hand off fret board. Good? Yes, Place hand on thigh and repeat, slap your thing between each strum. You can slowly increase your BPM’s until you fail miserably. Slow down a little and work your way back up in speed. Try it with your eyes closed for a great challenge. Repeat for other chords (not just these 3). You can always up the speed.

Feel good? Set metro on 30BPM and practice those 3 transitions individually. Increasing your speed slowly. Feel good? Try playing the progression that you are trying to get, ie GCDC. You can go 4 strums per chord DDDD switch; 2 strums per chord DD switch; 1 strum per chord D switch.

I have only been playing 2.5 years but to this day I still do this routine when I come across a chord or transition that is keeping from playing a song or TAC challenge. Sometimes the practice is 1/2 a measure at a time.

Long winded, sorry, but I think this might help build your muscle memory.

Strum away

[JimQuiz]

My observation… if I hit the strings individually with my thumb pad (thenar eminence), the low E, and maybe A make the percussive sound. The other strings offer little.

I would agree with JumpinJeff ‘The thumb is contacting primarily the Bass strings and really it is mostly the E and A string that makes the snare sound’.

I also got more sound moving towards the nut while fingerpicking over the sound hole.