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Discussion Starter #1
Hello, my PS90 magazine pops out every other shot causing a jam. I've only shot the gun suppressed with a surefire socom556RC on a 10" barrel. Four different magazines do this using AE 5.7. This gun ran perfect as described until I switched out the magazine catch for a man kave extended model. I love the way the new catch feels, but hate the jamming. It has been months since I installed the catch and just recently fired it for the first time. Has anyone else experienced this? I'm thinking it's either the catch's dimensions or maybe the spring is bad. Thoughts?
 

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I know EA sells higher strength springs for the catch. You may also need the higher power carrier springs to for suppressed shooting. Check out EA, he's got some great info and upgrades.
 

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Definitely contact Mike to ensure you didn't get one maybe a QC slip, but he uses pretty top notch machinists, so that may not be likely :D How many rounds total is through your SBR?
 

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Too much back pressure. Remove the can and I bet it doesn’t pop up. You need one of the EA heavier bolt weights.
 

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Discussion Starter #6
I did a quick test today. Switched ammo to FN 40 gr (blue/white/black box) and popped a few rounds off. Not a single hiccup. The FN ammo and AE ammo are both 40 gr. It must be right on the cusp of too much back pressure. Hopefully a stronger spring will work. Elite Ammo shows it as out of stock. Maybe I can throw a few washers in there or something to simulate a stronger spring just for testing purposes.
 

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I find SS195 and SS198 as well as my fast handloads to be too much back pressure when using the 22 size suppressors on the PS90 (long or short barrel). The 16" barrel was the worst and I needed the EA rate reducer weight for it to run correctly when suppressed. Now I only use my rifle cans, not rimfire, and it's a far more pleasant experience.
 

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With the blowback operation of the PS90, using a small volume suppressor with such a high pressure round will result in mag pop.

The solution is to use a larger volume suppressor or a suppressor made specifically for the platform like the Gemtech SFN57 or SAR57 suppressor. I also have good results using a 9mm can or any larger can.

The 5.7x28mm coming in at somewhere between 42kPSI and as high as 50kPSI depending on ammo places a lot of pressure in the can. When there is that much pressure being restricted by a small volume can, the pressure has only one other place to go to escape, by returning through the chamber and thus popping the mag.

Better matched suppressor.
Stronger mag release spring.
Heavier rate of fire stabilizer.
Better ammo selection.
Different powder if you roll your own.
 
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