Extractor O-rings for your carbines. I hope this isn’t old news.
PN: 1201T16 Mil-spec Vlton #60 O-ring, chemical-resistant and high-temp (+400 degrees F) rated. $4.82 for 50, plus shipping.
PN: 9464K11 non mil-spec, Vlton - $5.55 for 100, plus shipping.
Enjoy!
BTW #60 O-Rings work great under 1911 grip screws also. Now we ahave a two fer,
nicholst55,
Sweet. Thanks for the heads-up, sir. I appreciate it. Those both are pretty good deals. 
How often should these O-rings be replaced?
Whenever water starts leaking.
Didn’t help much but it was funny:D Obviously, these O-Rings are wear & tear items. I’ve put 230 rounds through my my M4 thus far (last Sunday). Do I need to order more NOW or am I good for a few more range sessions? I’m sure I’ll figure this our over time but thought I’d ask since this thread seemed like a handy vehicle for doing so.
Being new, I don’t mind being ignorant. I can fix that by learning.
I would never run a gun that needed an O-ring to extract properly.
Even BCM acknowledges that they aren’t necessary… but customers want them, so they include them in their bolt/extractor kits.
Thank you Demigod. That’s information I can store for future use.
If you have a black insert and a H/D extractor spring, there’s no need for the o-ring.
They fall in the same category as the accu-wedge.