You may have to pep them up a bit. Cause the gun may barely be coming back from the recoil to spit it out.
Example 7/8 oz with a ____ grains of _____ powder may be too light. So with those recipes you are nowhere to exceeding the maximum. Kick up a half grain at a time until they cycle and eject. Make like 10 of each load and shoot like 3 singles, load 2 shoot the 2 like a skeet double target and then load 3 and shoot them fast if you can pass those tests. You should be good.
I do the loading sequence part when I wanna try a new hull to make sure they will cycle.
Clean the gas ports? Assemble the gas valve correctly? I've only had this happen to my Teknys once and it was operator error during assembly after cleaning..Your shells should eject 6-10 feet from the gun, anything less you have a problem..Try the above link..good luck
You shouldn't need to drill the ports out, just scrape them out with progressively larger numbered drills by hand, until you get to a size that won't fit, even with a little effort. I don't know about a 391 but in a 300 a #26 will usually go and a #25 is a no go.
Correction: I meant 303, not 300, in earlier post.
IL,I would first determine if it is a failure to eject problem or a failure to feed problem. If the bolt is trapping the empty shell in the ejection port, you got a gas mechanism issue. If the empty is clearing but the next round isn't feeding you probably have a bad lifter. 1/8 ports should run 7/8 oz 1200 fps shells, shouldn't need to go bigger than that.
You want to be careful with drill bits in the gas ports, you do not want to break one off in your port. Go easy with out removing metal. You should not need to enlarge the gas ports in a 391 in 12 ga. Mine will cycle low recoil rounds. You should pull of the stock and the end cap of the recoil spring tube will come off. Clean the spring and run some patches through the spring tube. They can gunk up and the factory grease is heavy. Run synthetic oil and light grease it will not get heavy bodied in the cool weather slowing down the cycling.
Do not use a drill bit larger than 1/8th. You don't need the the spring kit from Coles. Your gun should eject the shells you're using and you need to find the cause.
Make sure your extractor isn't broken, and check the ejector as well.
The ejector is a little spring loaded piece in the inside of the receiver in the side of the chamber away from the port. It could be broken or missing.
Wow...lots of advice here. Who to go with? First off, unless you know what you are doing, I suggest a visit to a competent smith. You are infinitely better off having the problem properly diagnosed and repairing /replacing only what is required. Your 391 should cycle those factory loads easily. There are many variables that can lead to ejection/extraction/cycling problems...extractor, ejector, recoil spring, gas valve, shell lifter...you get the idea. Let someone knowledgeable lay eyes on your gun, and my guess is the problem will be readily apparent. Better, and cheaper, to fix it right the first
time. BTW...don't attempt to enlarge the gas ports.
You should go to the website: Shotgunworld.com, forum "I love my Beretta."
There is a wealth of information written by a shooter with the pen name
of Seamus O'Caisides. He also has published a manual that every Beretta 391 owner should have.
It may be some ridiculously simple thing to correct your problem. You shouldn't have to spent $100 or more for a gunsmith. There is hardly anything on a 391 you can't fix yourself.