Cracked Ejection Port!

[JackFlak]

Hey anyone ever seen this before? My old MPA 30T upper cracked in two places around the Ejection Port. Yeah, I put many steel cased rounds though it when I was young dumb and naive LOL. I've learned so much since then. Off shelf brown, silver bear and wolf - lacquer cased and plain steelies. So, just sharing this in case you're about to run steel - don't do it!
This was an old MPA, so maybe the Cobray and other originals are more durable in that area? Who knows

 

[Slowmo]

How did using steel-cased ammo cause the cracks? Is that a known issue? I’m struggling to envision why that would happen.

 

[StenAtopia]

I’ve put many thousands of rounds through my FA Mac’s using steel cased ammo. Never seen that. Also MPA products are Laser CNC machined. That’s very odd. Hmmmmmmmmm

 

[brenbuilds]

Generally steel cased ammo is not an issue. Some firearms may be less tolerant of it due to case rigidity of the harder material. However, Aluminum case cartridges that CCI produces can pose a problem in open bolt guns due to the low tensile strength and high malleability of Al compared to brass, or steel. I have seen cases rupture Al cases rupture and damage UZI feed ramps or flex the ejection port wall of MAC uppers.

Masterpiece Arms has had QC issues over the years, so this could be a a fault intrinsic to the gun rather than ammo, but there are many variables at play here.

 

[JackFlak]

Not a big deal, wanted to share that with you guys. I had fun with that thing over the years. It must have been a dud receiver

 

[Slowmo]

Not a big deal, wanted to share that with you guys. I had fun with that thing over the years. It must have been a dud receiver

Any idea how many rounds it lasted before it gave out? I wonder if they’d handle it under warranty.

 

[JackFlak]

Any idea how many rounds it lasted before it gave out? I wonder if they’d handle it under warranty.

Oh man I have no clue. I picked it up in maybe 2004 at a gun show, blasted a ton of rounds through it over the years. By around 2008 is when it cracked. I contacted MPA - they were defensive about it. Asked if I'd used custom reloads, plus P etcetera. Said there was nothing they could do

 

[cajun 22]

Sam could weld that right up.

 

[JackFlak]

Sam could weld that right up.

Practical Solutions? I like those guys. I may give em' a call, but I picked up a barreled upper from them to replace it already

 

[timkel]

I have repaired a cracked receiver by welding. It was not worth the time/trouble.
I don't think steel cased caused the crack. Ingram loves steel cased.