LMT MIM gas key failure

[dwd1985]

I have come across numerous discussions of MIM gas keys on LMT BCG's. There seemed to have been some heated debate years ago about whether MIM gas keys were the worst thing ever and a horrible cost cutting measure by LMT, or whether MIM gas keys were "nothing to worry about", with LMT firing thousands of rounds with no failures on any MIM gas key'd rifle.

Anyways, a month or so ago, I opened up my older Defender MRP for cleaning, and the first thing I noticed was that the front of the gas key had "mushroomed", splitting in a few different directions, appearing to have peeled backwards in a few spots (like a blocked barrel on a rifle from old Looney Tunes cartoons). I contacted LMT immediately, and they had me send in the entire upper. Just received it back last night, and they replaced the gas key with a non-MIM one. Notes on the order state they fired 60 rounds of M193 and it functioned fine after gas key replacement. With them having fixed it and tested it, I'm comfortable with the rifle again. However, I thought I would share this with the forum since I read so many reports of people saying MIM gas keys were nothing to be concerned with, as well as stating they had never seen any pictures of a MIM gas key failing. As soon as I get home (in an hour or so) I will post up the pics I took of the BCG that I sent to LMT, so people can see first hand that yes, MIM gas keys can fail, and I'm glad that LMT doesn't use them anymore and replaced it with a new one.

[TXBK]

Was it malfunctioning before you noticed it and sent it back?

[LMT/556]

Interesting you found a deformation like that. All the keys on my new LMT BCGs are non-MIM as you described.

[dwd1985]

Was it malfunctioning before you noticed it and sent it back?

Nope, was working just fine.

[dwd1985]

Work order receipt


New gas key:

[STAMarine]

Work order receipt


New gas key:

I actually had that, and worse, happen to mine last summer. Daniel Defense BCG in a Bravo 11.5. I can't tell you what the cause was. Had some FTF and FTE until it quit. Didn't notice the damage until I broke it down. Does Daniel Defense have MIM gas keys? If not, is MIM the cause. Really I have nothing to add except that it's happened to me as well.

[georgeib]

Looks like the gas tube was misaligned and coming into contact with the end of the gas key, to me. Did they replace your gas tube as well?

[dwd1985]

Looks like the gas tube was misaligned and coming into contact with the end of the gas key, to me. Did they replace your gas tube as well?

Nope, only the gas key. The tube is undamaged.

[georgeib]

Nope, only the gas key. The tube is undamaged.

Did they replace the gas tube?

[dwd1985]

Did they replace the gas tube?

No, they did not replace the gas tube. The work order picture I posted is all they did to the assembly.