Is there such a thing as "TOO MUCH" extractor tension?

AR/M4 AR Technical Discussion
1

Lats weekend, when I was cleaning my SBR (LWRC upper) I found flakes of what looks to be brass inside the bolt in the firing pin channel. I mean, the isnide of that channel was covered with the stuff.

I thought that this might be from the PMC “Bronze” ammo I had been shooting but when I shot 40-rounds of PRVI yesterday, I noticed that there were a lot of brass flakes in the extractor groove.

Then I remembered that I did not see this phenomenon until I replaced the original extractor spring and (blue) insert) with a Buffer Technologies extractor upgrade kit that I had bought from Brownells. The kit came with an extractor spring, black rubber insert, and o-ring donut.

Could it be that I the extractor is exerting too much tension against the case and ripping flakes off in the process? Or could this be something else? FWIW< I am using the H2 buffer and Wolf extra power buffer spring that came with the upper. TIA.

2

Run it without the o-ring and see if it stops. With a piston upper you don’t need a o-ring.

3

That’s just what I’ll try tonight. :slight_smile:

4

Yes there certainly can be too much tension.

Any ejection issues or just the brass flakes?

GotM4 already told you what I would try.

Hope it works out for you without the o-ring!

-RD62

5

There has not been any extraction issues since I replaced the extractor. The previous extractor seems to have worn out when some brass flakes got stuck in the chamber and cause failures to extract.

I tried it without the o-ring and still had large chunks of brass in the bolt’s firing pin channel though. I re-installed the original extractor (blue insert) and will test it later today.

But only if it functions - last night I found out that the forward Torx screw on the key broke on me. Jesse of LWRC is overnighting a replacement BCG to the hotel where I have reservations for at South Hill (talk about excellent Customer Service) so I can use the setup in the Vickers class this weekend.

Now I know why I become a SW Tester full-time. If something can go wrong with anything, I’ll find it. :rolleyes:

6

My Sabre Defence came with a defective bolt that shaved brass. Eventually one of the shavings got into the ejector tunnel and I had a single-shot(how I discovered the problem). It was a bolt-face dimensional issue. I suggest finding out what is causing it (possibly your tension) so you don’t experience a similar failure.