Tag for future reference.  BTW, there are many different elastomeric compounds used to make O-rings, and not all have the same capabilities when it comes to temperature/fluid/tear-resistance.  I can see arguing about the merits of the price difference between a Defender and a Crane O-ring, but dissing the $1 price for a part that ADCO sez will go 10K rounds seems overly frugal to me given how much time/$ we all spend on our weapons.  Where else can you buy life insurance for $1???

Quoted: the CRANE O-Ring

Damn, I love that term.


Almost sound like Crane produces their own "special" O-ring.

Quoted: Quoted: the CRANE O-Ring Damn, I love that term. Almost sound like Crane produces their own "special" O-ring.

+1

I run Wolff springs only, even in my M16 with 11.5" uppers.  For a while I tried using crane o-rings or D-Fender rings in addition to the Wolff spring, but all it did was make my bolt not close on the first round on occasion.  I also noticed a friend was trying to cure his problems by using both and while it improved his extraction, for a while, it made the extractor brutal on the case head, badly marring the case heads, wearing his extractor, and ending in ripped case heads (he needed to address his problem another way, I think he had a tight/rough chamber).  I'll use an o-ring device if I ever find I need it, but not until then.

I found this photo on the NDIA SOPMOD PROGRAM OVERVIEW Presentation -May 2005:


The photo shows gas rings. Are these different from USGI?