I have read in other threads on this board that for mid length guns you do not need to use the O ring for the extractor spring. Is this correct, and would it hurt anything to use it anyway?
I have read that it can cause feeding problems (per gotm4) but I don’t understand how this could come about. I understand the extractor is under more tension with the O ring, but I understand that is what helps with extraction on a carbine length gas system where chamber pressure has not dropped and the extractor needs mor umph so to speak. How does it cause a feeding problem when the bolt is returning and feeding and chambering a round? To may way of thinking, the bolt return, and extractor popping over the lip of the new round should be about the same on carbine vs. middy gas systems.
Too much extractor tension can overpower the ejector spring. Essentially the empty is extracted, but sticks on the bolt face and the new round can’t feed.
O-rings are needed for the reason you describe, but this situation really manifests itself more with carbine-length gas systems, and especially SBRs from what I understand. For mid-length ags systems, they aren’t needed.
I’m no extraction expert, but my 16in BCM middy has run flawlessly with no O-ring and the blue insert that came in my Daniel Defense FA bolt carrier. That’s with a mix of Federal M855, some Hornady TAP 5.56, lots of Silver Bear 62gr HP, and even some reloads from friends. Mags have been a mix of Pmags and USGI a friend brought back from Iraq.
Basically, it’s ate everything it’s been fed with no O-ring a a blue insert. YMMV…
Great info guys, and thanks alot. I guess I will take out the O ring on my BCM middy as it’s not needed. I did notice that my department issue Colt M4 did not come with an O ring. I put one on, as obviously it’s a select fire carbine length gas system. I was just not sure on the middy.
All our bolts use the rifle spring and 0-ring, no issues on the 16" mid. I would not use an extra power spring and o-ring.
The o-ring lasts longer that a spring, it may not be needed with the correct spring but how many people replace extractor springs?
Carbines and SBRs will run well with the extra power spring/buffer OR the rifle spring/o-ring. Thus no gun “needs” the o-ring, it’s just a different (I say better) system to increase extractor tension.
When I received my BCM BCG, the O ring was packaged separately. Upon examining the bolt assembly, there was no O ring in place over the extractor spring. I wrote Bravo Company with regard to whether the O ring was required. This is the response which I received.
" The O-ring wraps around the extractor spring if extra tension is required.
You probably will not need it as the BCM extractor springs are all ready stronger than Milspec."
ETA: To keep things in the proper context . . . The BCM BCG was ordered with a 16" middy BCM BFH upper receiver group.
I recently cut a blue insert in half and placed it inside the extractor spring seating area. No spring was used. The weapon functioned without any problems. How long would that last? I don’t know. I certainly wouldn’t use it anywhere but the square range…but it did make me chuckle.
o ring and extra power springs were created as a response to the extraction problems the carbine gas system had. Middys shouldn’t have that problem and arent required. I guess you could put it on but not sure what it would solve.
I think it’s safe to say you don’t “need” it but OP asked if it will still work. I have to say yes you can use it anyway, if you just want to. I run a G&R Tactical bcg in my BCM middy which has the extra power spring, black insert and o-ring. I have had zero probs. So do you need it…no. Can you use it anyway…yeah if you want.
O-rings can be used in midlength, intermediate and rifle length guns. BUT they do sometimes cause problems. These problems are feed problems and sometimes failure to eject problems because there’s so much extractor tension that it’s overpowering the ejector. I see these problems in customers guns about 2-3 times per month. People are fixing things that aren’t broken. I think it was MarkM that once said that not everything needs a fix or something to that effect.
The whole thing is a system. If you start messing with one thing you effect the other things.
I had the bcg I mentioned as a spare and dropped it in the way it came. It was not a “fix” for a nonexistant issue or anything. I wanted to see how it performed and it has been perfect so far. So like I said you can use them if you want, however, they are not a neccessity. Not to say someone other than myself won’t experience said “problems”. I agree wholeheartedly with the whole thing is a system and when monkeying around with it things are likely to go wrong!
To the OP, if you decide to try it out and have concerns then you now know where to start. Like gotm4 said sometimes there are issues. If you don’t like the idea of trial and error then don’t use the oring and you’ll be gtg.