If your abs have never been sore from chin-ups, you haven't gone heavy enough. Unfortunately, the chin-up is considered a "reps exercise" by many people. Their goal is to do a lot of reps, and that's the only marker they use for progression. That also means that bone-skinny guys are considered the "best" at chin-ups.
Those guys, and anyone else who can get at least 10 strict reps of chins, need to shift their focus to heavy work. Lower-rep, heavy chin-ups can be just as ego-stroking as cranking out sets of 25 with bodyweight, and your upper-body strength and muscle mass will skyrocket. Your back, biceps, and yes, even your abs will be stimulated in a whole new way.
The 25 Reps Method
The term "chin-up" typically means using an underhand grip on the bar, usually with a narrower spacing between the hands. This will put extra emphasis on the biceps and still nail the lats. "Pull-up" usually means using a wider, overhand grip. This method works with either style, as well as for neutral grip – palms facing each other. Pick your poison. Want to use gymnastic rings? Cool. (We'll use the term "chin-up" here for simplicity though.)
Step 1: Establish your 6 rep max on the weighted chin-up. Add weight with a dip belt, weighted vest, chains, or by holding a dumbbell or Olympic plate between your legs. Keep these strict. If you have to kip or swing to get the last rep, that's not your 6 rep max; that's your 5 rep max. Lower the weight a smidge and get 6 "clean but tough" reps.
Step 2: You're going to perform 25 total reps per workout, using several sets with that 6 rep max weight. It doesn't matter how many sets it takes, and it's fine if you're down to doing doubles or singles at the end.
Your 25 total reps may look like this:
Set 1: 6 reps
Set 2: 6 reps
Set 3: 5 reps
Set 4: 4 reps
Set 5: 2 reps
Set 6: 2 reps
Total reps: 25
This is just an example. Everyone will be a little different here. Just get 25 total reps with your 6-rep max, taking as many sets as you need. (If you can do this in two sets however, you clearly didn't go heavy enough.) Rest as needed between sets. This isn't metcon. When you can easily get more than 6 reps on the first set, add weight.
Step 3: Perform weighted chin-ups in this manner 3 times per week on nonconsecutive days for the next four weeks: Monday, Wednesday, and Friday for example. If three times per week is too rough on your elbows, perform twice per week for 6 weeks.
Note: If your elbows are cranky, you can also vary the grip style and width. The neutral grip is the "nicest" to the elbows. This means you'll have to adjust the load to meet the parameters of the plan, but don't sweat it. You'll still get great results.
This is a specialization program. So no matter what's on the schedule for that day, start the workout with chins. It's pretty easy to adjust the rest of your training around it. You'll still want to get some horizontal pulling in (rows, etc,) but may not need any additional biceps work if you choose close-grip chin-ups for this plan.