Had an odd AP-16 issue today

[AlaskaAirgunner]

I was shooting the AP-16 this morning and everything was going great. The last shot all of a sudden was three times as loud. I started to try and troubleshoot the problem and found that there was some air blowing back around the probe and magazine. Then I found an o-ring inside my Tanto moderator and found out it was the o-ring that goes just inside the breech end of the barrel to seal the probe.

I inspected it with a magnifying glass and the o-ring was totally undamaged. I lubed it with a little silicone and put it back in its groove and everything is back to normal and shooting awesome. The only thing I can think of was that the o-ring was really dry and the probe or pellet stuck to it a little and forced it out ahead of the pellet. 

 

[BigTinBoat]

My guess would be that the bolt wasn't all the way closed when fired.

 

[AlaskaAirgunner]

That would actually make more sense, but definitely has not been fired with the bolt open. What really surprised me was that there was no o-ring damage at all. I put about 150 pellets through it this afternoon after lubing and reinstalling the o-ring, more than I have fired total since I received the gun a few months ago, and there was no issues at all. Super quiet with the tanto and accurate.