PSA Premium BCG

[CUatTheEnd]

One says Mil-Spec O-Ring the other says Extractor O-Ring insert. What's the difference? They also both say Milspec Carpenter No.158 steel bolt? The o-ring is the only difference?

[J]

The original design didn't even have an o-ring. Just the spring. Both will likely run just fine for you for many thousands of rounds.

[CUatTheEnd]

Sorry for the rookie questions tried to google it, but didn't find anything.

[ChunkyMonkey]

Just understand this.. PSA premium is comparable to the minimum specs from any good companies. The reason they mention carpenter 158 bolt is because they also sell cheaper version bolt in 8620. Car 158 is the standard milspec for bolt.