I just realize how damn old this thread is....and I've added nothing new. *Feeling intelligent*
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I just realize how damn old this thread is....and I've added nothing new. *Feeling intelligent*
I ordered the MK-18 last September so that is as recent as I can state, and it's a sample size of one. You may want to shoot DD an email to verify, but they do build military grade guns, so I can only assume that the 4 coil spring is standard on their BCGs. My DD LW has a BCM BCG installed (I bought the upper and lower separately and added it myself), as well as two other carbines. When I first joined M4C seven years ago, and purchase my first 6920, it had a silver 4 coil spring with a blue insert. As far as I know, the 4 coil spring is milspec, so I considered it an older version. As far as the origin of the 5 coil spring, I recall reading about it in small arms review magazine back in the day, which had an article on the SOPMOD kit. It stated it was part of a SOPMOD (I can't remember if it was in Block I or II) bolt upgrade kit, along with the black insert and O ring, developed thru Crane as a replacement for the milspec 4 coil spring. I could be wrong since it's been many years since I read it. Hopefully, someone with more in depth knowledge will chime in to verify that claim.
Thanks for the info and links. I'll read that thread over the next couple of days.
I appreciate the follow up. Until I asked about it here I had been under the assumption that the newer 5 coil spring must be the current mil-spec. That's why you shouldn't assume.
Either way I have installed the BCM spring and black insert (no O-ring). I also backordered one of the copper colored colt springs linked to above. I'll run the BCM spring and if/when it gives me trouble I'll throw the Colt in it and go from there. I'm not going to worry too much about it in the mean time though. It's not like we're being bombarded with reports of the BCM springs causing problems.
Thanks again to everyone who responded.
Pretty sure that is in the MK18 ndia thingy.
That was before Colts copper or "gold" spring I believe. DD is a good company but in my experiences their MK18 barrels are very overgassed and their extractor spring is underpowered compared to Colts current spring.
The 10,000 round thing Andrew did for lucky gunner showed the Colt springs lasted far longer than standard springs which were good for around 5,000.
Springco recently debut'd a new 4-coil spring that is not quite as powerful as their original AR15 extractor spring....I wonder if this is closer in performance to the new Colt copper washed spring?
Thx for adding that about Andrew's test at LG....I had forgotten that.