i was changing my extractor spring for the first time and that little rubber insert went flying across the room. i cant find it. what is its purpose? do i really need it? can i go ahead with my spring change any way? my bolt is sitting in pieces on my work bench because im not sure what i should do here. where can i get more? again, im talking about a cylindrical rubber piece that goes inside the extractor spring, not an o-ring or any thing like that. thank you.
Yes the insert is necessary. I wasnt able to find the insert by itself but this is what you are looking for:
It’s called the extractor spring insert. Yes, you can shoot without it-but I recommend replacing it as soon as you are able.
Would the O-ring, with no insert, be a viable alternative? 
in dont have any of those 0rings. but i was able to find a pack of 10 inserts at brownells which i just ordered.
How many rounds at time of extractor spring change? Was the previous spring worn or were you upgrading? I know it’s not relevant to your situation but, I was just curious.
No because the O-ring adds extra tension to the extractor spring, the insert doesn’t.
What is its function then (the insert)? I’m not questioning that it should be there. I just don’t really know what it does.
It basically provides stabilization for the spring and cushions it.
Oh Ok. I had always assumed it was there to provide additional tension. Thanks for the clarification.
i was about 6k of mostly milsurp deep and it was time for a buffer tube spring change. i went ahead and ordered some spinco springs. while i was ordering i saw for and extra $2 they give you some extra power extractor springs with your order that are supposed to omit the possible need for o-rings and such, so i thought i would give them a try. so, no. my extractor spring did not need replaced. just a little experiment to check out sprinco producs.