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Discussion Starter #1 (Edited)
So I just received my new LSC 9mm flat today and inspecting it I noticed a crack that might concern me. This is my first HK flat so even though I suspect this ultimately won't be a concern, I'd rather double check with those that have seen many more to confirm.

The concern is how close the crack is to the ejection point. Since there are cracks around both sides of the rails I believe this is just part of the stamping process, but is this crack too close to the ejection port that it poses a real risk of cracking the rest of the way through? Or is this 'normal' and in the event it does crack through I should just reweld it?

Thanks for any feed back.
 

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That pic is of the "inside" of the flat, correct? The trunnion is going to be welded to the flat at that point anyhow, so... meh. Just weld it up.
 

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Yes it's the inside. I just wanted to get a close enough picture to show the distance. I suspected it's not a major problem, but before I folded it I just wanted to check in, with those with more experience. Thanks!
 

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Those cracks are not a problem. A little TLC while welding the trunion and you're fine.
 

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Those are stress fractures from the stamping process. Look at a finished gun. You see the welds on the corners? Those are why those are there. On the centerfire rifle calibers the weld is a contiguous bead. It is also a tack point on the rear trunnion/receiver interface.
 

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those points arent actully welded to the trunnion on a mp correct?? I know weld goes on a g3 from top to bottom but not on a mp5 type fiream to preven actually cracking on these points correct or not correct?
 

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have to keep that in mind next time.. dont believe in part sourcing I ever have encured a tackwelded one other then g3 trunnion but then again ive not seen many things.
 

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those points arent actully welded to the trunnion on a mp correct?? I know weld goes on a g3 from top to bottom but not on a mp5 type fiream to preven actually cracking on these points correct or not correct?

i just demilled mine (mp5) and it was NOT welded in any way to the trunion itself. i posted a pic in my build thread and im pretty sure you can see there are no marks on the trunion and when i demilled it, the old pieces of rec peeled right off (in that area anyway).

but that had left me wondering if i should weld it to the trunion? i guess it wouldnt hurt to have some extra spots welded.
 
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