Glock 19 MRDS causing reliability issues?


Regular Member
Chris, I'm kind of surprised at your questions since you are claiming to be knowledgeable about this. Did you actually look at his pictures?

The chamber question is pretty basic. Look at the OP's third picture above, that is exactly what happens with a round that won't fully chamber. That issue can be caused by a number of things - a tight chamber, oversized bullet or case, fouling or buildup in the chamber, etc. That's why I said we can go into that further if needed. I'm not going to guess about the likely cause without more info.

Other than saying I wouldn't worry about it, nothing else I said was an opinion; it's all facts based on a lot of years of working on guns and troubleshooting issues. Milling slides for red dots is part of my skill set too, but the main thing is being able to understand how everything in the gun works and which problems can cause certain symptoms. You could be the best race car instructor in the world but that doesn't mean you know how to work on race cars; understanding and troubleshooting problems is a different skill set than teaching how to use a piece of equipment.

If that slide cut broke into the safety plunger hole a lot deeper, and the malfunctions only happened when an optic was installed, and it affected trigger pull, we could surmise the safety plunger might be obstructed by the optic. However, the OP clearly said the problem happens with or without the optic, he didn't mention trigger issues, and his slide milling barely broke into the hole.

Unless there's a chip of steel or burr in the hole, that small break through has no affect on function of the gun; the safety plunger should still move freely in the hole. If there is a chip or burr, removing it should clear up any issues. OP, you can check that by just depressing the plunger and making sure it moves freely.
Without having it in hand we’re both guessing and I agree the options you listed are possible although far less likely.
The gun worked. The gun was then milled and now has malfunctions.
Any milling job that touches that void in the frame is wrong. A hobbyist milling slides in their garage may say it’s acceptable but a machinist would disagree. I’m not calling you a hobbyist, you may be as good as Doug over at ATEI but I believe he would agree hitting any the void is unacceptable and the likely cause.
As far as ammo. I admit I’m blessed to shoot quality duty as well as quality practice ammo. However I’ve shot pretty much every other type of cheep ammo and haven’t seen a round so out of spec it wouldn’t chamber in a Glock. Garage reloads not included.
I’ll go out on a limb and say the failure to feed is from the raised rear of the trigger bar cruciform dragging on the firing pin lug. It does this because of pressure from the firing pin safety pushing down on the lifter portion of the trigger bar and the leverage it transfers to the rear. I realize the picture included doesn’t demonstrate this and that some may not need it but it can help some visualize what I’m talking about. The picture demonstrates proper engagement but imagine the inverse and the lug getting caught going forward.

OP. Fire a round and keep the trigger pinned to the rear. When it malfunctions keep the trigger pinned and push the slide forward. Does it feel caught? If it’s stiff release he trigger and it should go into battery. C0B98F74-D7E7-4BCF-824D-3CD2ED6565E9.jpeg I don't know everything but this fits right in line with what we’ve observed.


Regular Member
Chris, I am a machinist. You're way out of your lane on this stuff, maybe you'll realize that as you learn more someday. You're doing too much guessing and ignoring the details that don't fit your idea.

Think about the fact the gun malfunctions without the optic installed. Then there's the point about the broken-through part being so small that the optic can't interfere with the plunger. Neither of those match with your claims.

Most any machinist and gunsmith who knows what's up with this stuff will agree that breaking through that cut is not good, but saying that small breakthrough is the likely cause? Nope.

There could be a burr or chip that's causing a problem, we don't know. If there is, removing it should fix the problem without needing to replace the slide.

David Mayeur

Regular Member
Network Support I
If the optic cut was far enough forward to puncture the plunger hole and the pocket was cut to the exact RMR length, then it can cause issues. However, the OP was able to pull the trigger firing the pistol and it's failing to go back into battery. While I would still contact them about a slide replacement, because that's poor work, I don't think that's the issue.

The OP says it's happening without the optic, so I'm assuming that was fired without the screws installed. That potentially rules out an over sized screw binding with the extractor depressor plunger. I would detail strip the gun, check for wear near the barrel hood. There is a potential that the cerakote is overly thick in that area. There are honestly many reasons these malfunctions can happen. It could be as simple as a worn RSA.

Arguing about who has more experience with milled guns isn't helpful to anyone.
Thanks everyone for all the good info!!! It was fired without the optic and optic screws. I tried it with 115gr federal, 115 critical duty, 147 grain umc, 115 blazer, 124 gr Winchester NATO all had the same issue. I tried a lighter and heavier recoil spring all has the same issue. The ejector channel was free of burs and the optic screw didn't protrude into it. I sent it back yesterday afternoon to the manufacturer and ill let y'all know what the verdict is.