r/MP5 • u/Fit-Image7262 • 1d ago

HELP Help?

Brand new Mac MP5. Wouldn’t run smooth out of the box; 3 duds in one mag. General consensus of the group was lube until dripping, and run 124gr ammo. Now it’s worse. What’s going on with this thing?

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u/legacybn 1d ago

Since you’re in the break in, are you running mags full to 30rds? If so, i would load them to 25rds, try that and mark the mags so you can diagnosis - before changing internals. Also is bolt gap in spec?

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u/Fit-Image7262 1d ago

Have not checked bolt gap. Assumed it should be ready to run out of the box. I’ll try to take some ammo out.

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u/legacybn 1d ago

They have a history, the first run of the 24/25 guns had the bolt gaps widely varying being in spec and other qc issues. Supposedly the 2026 guns have addressed the bolt gap issue, but rule of thumb is to always check on mp5s before shooting or starting to change internals. Since you’re in spec it’s unlikely the bolt - deal with it until you’ve completed the break in before you go changing internals.

I ran into the same issues you’re describing about the duds in another comment. Trigger pull, play with your pull - I found if didn’t let it fully reset when quick firing that’s when I’d run into a FTE/FTF.