All the previous posts have good advice.
When I was playing with 40 loaded long, I had the same problem with my gauge.
I ended up reaming the bullet portion of the case gauge.
Before you even think about reaming your gauge, clean it well and try again. Clean the failed rounds and try again. Inspect your rounds for non-concentric bullet seating and/or tilted bullets, crud at the case mouth, etc. Are you using the correct bullet seating stem? Are you smoothly stroking the reloader?
Try someone else's loaded rounds or factory in your gauge. Try your rounds in someone else's gauge.
Since you are not loading long, I don't think you have to do this, but if you just gotta ream your gauge, here is how I did mine. Find a couple of bullets that are the correct diameter and round. I used a micrometer for this. Or you have them, use pin gauges.
Using the perfect bullets, drop them through the case gauge. They should fall through.
If they stick, you may have to LIGHTLY ream your gauge.
I used an adjustable reamer and lots of oil. As soon as you feel the reamer scrape the gauge, stop, clean the gauge and try to drop the perfect bullets through. Stop as soon as the bullet passes through. Do NOT go one more pass for good luck.
Also, if you do load long (I know you are not) make sure your barrel has enough freebore.