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I was flipping through the Guns and Ammo Book of the AR15 and saw something about this D shaped polymer bumper that is placed around the extractor spring. Is anyone using this? Any need for it?
Thanks.
pg 117 of magazine noted above. This is produced by a company called MGI.
It accomplishes the same thing as a standard Crane O-Ring, it's just supposed to do it a little better. If you look at where it's going and compare it to the standard O-Ring, you can see how it might have some kind of advantage, especially in SBRs where ejection issues are supposedly more common.
It sounds good in theory and my 10.5" LMT has been flawless with it. Besides, after you've got $2,000+ tied up in a quality rifle & optics, are you really going to start splitting hairs on whether to drop $2 or $10?
The D-Fender is warrentied for the life of the bolt. IF it breaks, MGI will replace it no questions.
I don't mind spending a few bucks, just wondering if it acutally does anything. I guess it would be hard to say for sure since failure to extract doesn't happen all that often anyway. I at least wanted to see if anyone had it cause any problems with the extractor.
I have been using the D-Fender in two carbines. Each rifle has 3000+ rounds. I can't say that it heped or not, but the D-Fender didn't cause any problems in either rifles.
I've used them in the past with great results. Now I just run standard HD extractor springs and the Crane O-rings but only because I got a bunch of them for free.
HD Extractor Spring, Black Spring Insert, & D-Fender ring or Crane O-Ring should be considered a mandatory addition to any serious use AR platform rifle.
I've never run any o-rings or D-fenders. If I had a gun that needed one of these trinkets to run... I find another gun.