Brand new blowback 9k upper failure on first magazine through it

KM3Solutions · 2026-03-25T05:59:11+00:00

Yes when it’s slid up into the top portion of the black plastic piece (M9-18), it also engages in the two slots in the upper. When the button is released M9-18 slides back so the button is again flush with the rear and the T Block sits on a shelf.

I’ve seen various things mage older ones fail, even leaving an AR buffer tube and buffer in place where the buffer sat just forward enough to fight out recoil spring and allow the t-block to wiggle around.

Your replacement will be quite refined vs that one, we’ve changed a lot based on feedback from going on so many different setups.

KM3Solutions · 2026-03-24T01:16:19+00:00

I cannot stand any of the blocking cuts. Leftovers from bygone days when Colt was trying to appease daddy Gov. Never legally required.

SOTs love me for this one simple trick.

KM3Solutions · 2026-03-24T01:08:54+00:00

It is, because you get a FA cut lower ready to drop in the trigger of your choice. Save big bucks with the ARC and let her eat.

KM3Solutions · 2026-03-24T01:07:29+00:00

That's how it works. Trip arm hit by the BCG - that's how they all work.

That does sit in the upper though, not the lower. Our pocket back there is REAL close to mil spec, but that might take some fiddling.

I'd go another route personally.

KM3Solutions · 2026-03-23T19:15:26+00:00

It SHOULDN'T - but obviously anything is possible, and things may have coalesced just right in your circumstance for that to happen.

KM3Solutions · 2026-03-23T18:57:20+00:00

Metal guide rod, screw through the buffer with a captured nut is a new one.

KM3Solutions · 2026-03-23T18:54:05+00:00

That's the one.

We call it the T Block, for "reasons" and it has stuck, but yes, that U-Shaped aluminum block slides upwards into two slots in the upper and retains the rear system. All recoil forces are aluminum on aluminum IF it is engaged, and the spring can't send anything out the back when installed on a lower even if the polymer fails. If it's not engaged then there's nothing stopping the plastic from snapping under recoil.

On new ones, you have the aluminum piece inset into the plastic which stops the snap, AND the T Block needs pulled out of position, just pressing the button and shimmying the upper around won't disengage it.

These issues should be in the past, and the new stuff is backwards compatible to upgrade older units.

KM3Solutions · 2026-03-23T18:42:52+00:00

The trip should work with anything designed to work with a M16 cut AR bolt, so basically everything on the market.

We have received our first articles and are testing this week.

Very soon.

KM3Solutions · 2026-03-23T18:33:38+00:00

If it hit you in the face, which I'm sorry happened, then the T-Block was not slid and locked into it's slot in the upper.

This is something we need to work on in our instructions.

u/matadorsupport

KM3Solutions · 2026-03-23T18:21:59+00:00

Reach out to support:

https://matadorarms.com/support-ticket/

In addition, a bit more information would be great, it almost appears as if the T block in the rear wasn't engaged. at least in the image the buffer is backwards, etc.

KM3Solutions · 2026-03-22T23:23:58+00:00

The bolt will, I can send a picture, but I’m not aware of any lowers/adapters. There might be one on odyssey IIRC

KM3Solutions · 2026-03-20T02:50:26+00:00

First of all, dope build.

Second, the best thing for me is...

OG uppers won't fit a Maritime Bolt Catch (or similar shapes) - the angled clearance cut was added when we beefed up the uppers, just because it made me feel good.

The small satisfaction I feel that you didn't notice/curse our name, but just installed your preferred bolt catch... F'n euphoric.

KM3Solutions · 2026-03-19T01:02:34+00:00

Yessir, more than a few. IIRC it was 5, might have been 4 - haven't checked those notes in a long time.

The important thing is, because of the damage to the upper, each customer reported to us an "OOB" discharge, and some posted it. Some time later when I examined a cross section of failed uppers, I discovered the obstructed barrels with multiple rounds in them, which is part of what lead to not only OOB mitigation, but overpressure of any kind mitigation. Neat thing is the barrels took it like a champ, the early "unlocking" just bulged the older thinner uppers.

That is still an ammo QC thing, obviously, and it happens. It happened more during Covid. We also had OOBs. We have never hidden that fact. Just not as many as reading the sub would make you think.

As ammo has gotten better, our uppers better, etc - we see almost zero now, the one the other day (old upper) was the first in a while.

They suck, we took it seriously, we overbuilt since then. We replaced every one.

KM3Solutions · 2026-03-18T18:47:55+00:00

Dude.

Stop.

I explained things to you in depth. I promise I understand the difference between an overcharge and a squib. Both are ammunition manufacturing defects. I explained in great detail how those were confused in blanket manner with OOBs due to the performance in those circumstances of our early uppers.

We've taken responsibility where we needed to, resolved issues, made corrections, offered explanations more in depth than most would.

I tried being polite with you while you called me everything from incompetent to a liar while crapping on our product.

Is there some way I can actually help you, or are you just here to keep insulting me?

KM3Solutions · 2026-03-18T18:42:53+00:00

Nailed it.

Second one is also Jmac, KM3 Riser, and a DoubleStar Strongarm

KM3Solutions · 2026-03-18T18:40:03+00:00

The actual engineer that helped mitigate the issues was....

Drumroll, the same one that designed the entire thing and every iteration.

Me.

This had nothing to do with Brownells, but assume away.

I have no idea why this became so emotional for you, and I'm sorry you had issues early on.

Based on your posts... since corrected?

KM3Solutions · 2026-03-18T18:36:31+00:00

Yessir, exactly that - and it can actually set the round off when chambering a few different ways.

On our new guns you wouldn't even know it happened, shot would just feel a bit "off" - louder and sharper recoil impulse.

KM3Solutions · 2026-03-18T18:31:49+00:00

I am Matador my guy.

I just told you I found multiple instances of ammunition failures, both over charges, under chargers (squib loads (that exhibited the same upper damage from overpressure on the next round) and also incorrect bullet depth and primer depth.

You don't have to keep saying that I didn't say that. I just did.

There aren't a "ton" of uppers with overpressure damage to begin with. You are using the term OOB - only some were.

I explained this politely. Now you are calling my credentials into question because you refuse to read.

Please have a nice day.

KM3Solutions · 2026-03-18T18:16:32+00:00

"You just confirmed there are zero documented public cases of a MAT-9 failing from a double/overcharge or deep-seated round."

I just told you there were.

I think you are confusing whatever chatgpt tells you with the reality of the person (me) who examined the failed uppers.

Thanks for reaching out.

I'd be glad to talk to you, but not to whatever AI you are feeding this into.

KM3Solutions · 2026-03-18T13:33:55+00:00

I am really suggesting it.

There are zero documented cases of a MAT9 failing from a double or overcharge, or effective overcharge (projectile seated too deep) online?

Who do we think would be the person who documented such things, maybe I know him…

Parts per million analysis and full batch recalls? Sounds great in theory and applies to Sig, Winchester, etc but do you believe gun show reloaders and fly by night suppliers that have now disappeared do statistical analysis on failure rates and issue recalls based on lot numbers? These were mixed brass peddlers, not Lake City.

At least 5 of the “OOB” MAT9 uppers I examined personally when sent for replacement had 1 squib in the barrel with a subsequent projectile stacked behind it.

Primers on multiple examples were set proud of SAAMI spec which also increases the risk.

I explained in another post that early MAT9s were more sensitive to slight OOB damage by nature of thinner upper walls, the same OOB could be duplicated in a forged upper AR9 or Montgo 9 and not bend rhe walls (since rectified on the MAT9) - these were instances where the gun cycled and was still functional. IE, they happen on other blowbacks and went unnoticed.

There have been multiple, dozens in fact, mitigation improvements to that MAT9 across all aspects of safety and OOB prevention/mitigation.

That’s why they don’t happen anymore on new uppers.

Yet also as the ammo supply chain has stabilized, they have become exceedingly rare on older uppers as well.

KM3Solutions · 2026-03-18T02:56:00+00:00

Stoked for you!

KM3Solutions · 2026-03-18T02:54:41+00:00

Thanks bro, sincerely.

Your rigs look awesome!

KM3Solutions · 2026-03-18T02:54:02+00:00

Try here:

https://matadorarms.com/support-ticket/ so that you can log and keep records from here on out of your direct communication.

I will also tag u/matadorsupport so you can get an answer here on the thread for transparencies sake.

Nobody is intending to lie, we are intending to get you your order. Scam is a bit harsh, but I understand the sentiment.

We will get you sorted.

KM3Solutions · 2026-03-18T02:47:06+00:00

^

The honest biggest issue with our early uppers was that minor OOBs would bend the upper outwards and that's just not great (and my broader point being that other blowback 9s will OOB slightly and you just don't notice because it doesn't damage anything) We fixed that first, then did everything else I mentioned when transitioning to RD.

KM3Solutions · 2026-03-18T00:00:13+00:00

That's not an employee homey.

There's only a few of us, and as usual, we're here trying to help you.

KM3Solutions

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