r/MPX • u/Odd-Cherry-7022 • 3d ago

Problem with round going into battery

I recently got a MPX K and took it to the range today. When putting the mag in sometimes the round wouldn’t go into battery and I would have to rack it back hard to do so. Is this a common problem or do I need to upgrade/replace something?

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3

u/OG-warbucks Ronin SD, ILWT SD. MPX Mob, Milkman, Tisha 2d ago

Not seating the first round can sometimes occur if you baby the charging handle, especially on a brand new gun.

Make sure your mag is fully seated and rack it with a purpose for bit. It will break in the more you use/shoot it.

If the problem does persist, I recommend contacting Sig.

1

u/Odd-Cherry-7022 2d ago

I think I wasn’t racking it hard enough. I’m new to the platform and my ARs I usually rack with more ease

3

u/NyJosh 2d ago

Make sure you aren’t over loading the mags. You can force an extra round into the mag but it will be so tight that it’ll be hard or impossible to load. Try counting rounds while loading the mag as opposed to just going by feel. Alternatively you can leave one round out of the mags and see if that helps.

1

u/Odd-Cherry-7022 2d ago

Yeah I noticed I could squeeze an extra one in it. I think I wasn’t racking it hard enough. Going back to the range later to see if it’s any better

2

u/Jimothy_Jimmerson 2d ago

Did you get the MPX new or used? If new, how many rounds have you put through it?

2

u/Odd-Cherry-7022 2d ago

I bought it new from Sportsman Warehouse and roughly 150-200 rounds

3

u/Jimothy_Jimmerson 2d ago

I had the same issues as you with my new MPX, and it took about 400 rounds to break in. I'd suggest running it wet and giving it 200-300 more rounds to break in. Springs are stiff and tolerances are tight. Also, make sure you're not using flat-nose ammo during the break in period either, that will also introduce another variable.

2

u/thetruetrueu 2d ago

My mpx wont run flat tipped ammo with out double feeding. Round tip only.

2

u/PhilipD424 2d ago

You’re probably loading 36 rounds instead of the 35. I have this happen when I don’t count the rounds. I wish there was a window on the mags. It sucks counting the rounds…

1

u/Intelligent_Pin5598 2d ago

I would suspect your magazine as the likely problem if your gun is clean and oiled. What magazines are you using?

1

u/Odd-Cherry-7022 2d ago

The stock mags that came with it. I just strip clean and oiled it but the problem persists

1

u/Intelligent_Pin5598 2d ago

Does the feed issue happen with all your mags or just certain ones?

It could also be that your mags are not seated all the way. This can happen especially if you have a full mag. Is this a possibility?

1

u/DicedT 2d ago

Are you putting too many rounds in the magazine? The Thril mags can hold 36 rounds and be a pain to chamber a round.

1

u/kodkrysco51 2d ago

Mine periodically does this. It’s not super common but it happens.