J-Frame Trigger Problem

[El Cid]

Yesterday I was dry-firing my J-frame (M&P 340 w/ lock) when suddenly the trigger became extremely difficult to press. Everything else still worked properly (cylinder rotated, firing pin came through, etc.). But it felt like a 20lb press.

I locked and unlocked it several times (never used the lock previously) to see if that was the issue, but it didn't remedy the problem. I tried to removed the side plate to see if pocket lint or something was inside but the screws were so tight they wouldn't budge. I put some lube inside and that did nothing.

I let the gun sit overnight and was planning to contact S&W warranty, but this morning the trigger is back to normal. Has anyone had this happen to their J-frame? Is pocket lint the likely culprit (I blast it with a can of air periodically), or does that sound like the stupid lock?

This may be the excuse I need to upgrade to the Apex trigger kit and replacing the lock with the plug... but I'd like to diagnose the problem if possible.

Other than changing the grips, there have been zero modifications to the weapon, and it probably only has 100 +/- rounds of live ammo through it.

Thanks!

[Smash]

This happened to me on a 327 N Frame. The day I received it I dry fired for an hour or more with no issues. Put the gun down and picked it back up an hour later and started having your aforementioned problems. Removed the lock the next day and everything has been perfect since.

[T2C]

Make sure the cylinder release is moving freely. Also check that the ejector rod has not backed out and it is screwed in tight.

[El Cid]

Thanks gents - I'll double check those items.