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Scott B. wrote:

No I am not. Thought about it but I don't have the pliers. Will need to pick some up.

Will these work OK?
https://www.walmart.com/ip/173150481

Might, they've got to be long enough/thin enough to fit down inside the piston.

Mine look a bit like this: https://www.walmart.com/ip/TEKTON-Inter ... r/34648469

I've also got a switchable set to do the snap ring on the forend cap. Not sure if you've got that on the 390, but on the 391 it needs to be kept lubed. Long as the spring compresses it's okay. Take down after a few thousand rounds or so.

Scott B. wrote:

Glock4ever wrote:

rotor wrote:Same problem with my Beretta A400. I listened to people about using different combos to dissolve the junk and did a test. Chopped the junk off using a wooden pick and put in a jar. Then added all of the stuff that was supposed to dissolve it and weeks later, guess- none of it was dissolved, same little chunks of gunk. I wonder how an ultrasonic would work. What I do is pick at it with wooden picks and don't sweat it too much as the gun keeps working no matter what I do.

Got me some wooden skewers helped a bit to get the grime out of the piston. Good idea thanks

I didn't think to ask, but are you taking the piston apart before cleaning? It's a 100x easier if you have some long-nose spring clip pliers, remove the clip, washer and inner piece. Have a small container ready for those parts as they are easy to lose.

I used to not disassemble mine, but the time saved in cleaned has proven to be worth the extra effort.

rotor wrote:Same problem with my Beretta A400. I listened to people about using different combos to dissolve the junk and did a test. Chopped the junk off using a wooden pick and put in a jar. Then added all of the stuff that was supposed to dissolve it and weeks later, guess- none of it was dissolved, same little chunks of gunk. I wonder how an ultrasonic would work. What I do is pick at it with wooden picks and don't sweat it too much as the gun keeps working no matter what I do.

Scott B. wrote:Edit: I should add, I sympathize. I shoot the gun a lot and it takes the longest to clean of any of my firearms. That piston in particular takes a lot of work. Beretta service guy said not to oil/lube that part or the gas valve to avoid excess fouling.

I've got a Beretta AL 391 Teknys Gold, it's the generation after the 390 but uses the same piston.

When I do a full tear down and clean, I soak the piston and gas valve components overnight. Attack the gunk with a bronze brush, soak it again and then I take some very fine steel wool (I can hear the screaming from here) and remove what's left. You won't damage the piston. Worst case scenario, you can buy a new piston. Talked to a guy at the range once who swore he'd rather buy a new piston than than clean the old. I think he was kidding.

Sometimes I'll dunk it in the sonic tank and use the tank's heater to help soften that crud up.

The bolt, trigger pack, and most of the rest of the 390 looks to be the same. What the 391 doesn't have is the loose spring in picture #3 of the same page.