Assembled a 9 mm RR 15. Only firing as a single shot. Will not cycle the action. Everything moves freely when operating the charging handle. Only thing that is odd to me is when the upper is off the lower or tipped up from pulling the back pin the bolt carrier will slider backward extending out of the rear of the upper. The spring and buffer hold it from doing this when the upper is installed on the lower. No gas tube on the 9’s. It’s the buffer to heavy or is there something wrong or missing on the bolt carrier. (Slides freely no latch tension when not on the lower.
Colt mag adapter ( fit in nice)
9 mm upper and bcg from AR15 Parts.com.
Stoner buffer tube
9 mm buffer 8.2 oz
115gr. fmj 9 mm target ammo.
Any help would be great.

It does look like your buffer may be too heavy. Try ~5.4oz.

Try some 124’s.

Probably a blessing that it jammed, it will blow through 600.00 of ammunition in half an hour

I don’t understand why you bolt is pushing back out of the upper - from your description - I’m getting that it backs out of the upper a bit when the upper is opened and muzzle down?

It should stay forward, but there’s no tension from locking lugs, it will freely slide out - until it hits the ejection port door if closed, or the rear of the race for the alignment block on the top of the carrier/bolt.

No locking lugs on a 9mm bolt, its a blowback design. The buffer spring holds it in place. Your buffer is the correct weight for a 9mm. What's it doing when you fire it? Not ejecting? Ejecting part way? What lower do you have?

Not ejecting. Once when I had help watching it tried to open a little. Called AR parts and they recommend cutting a coil off the buffer spring one at a time until it cycles but not more than 3 coils. He said my buffer was correct weight and if cutting coils didn’t work to get back with him and he has a pistol buffer that for sure will work. The bolt stays in place with the dust cover shut. Moves back when open as it’s designed. No issues there. AR parts got back with me within a day of my email and were very helpful. Thanks for your help as well campfire. Let you know when it’s running smooth. Too many holiday get togethers last few days to play with the 9 lately.

Telling you to cut a coil or 3 off the buffer spring was not being helpful.

Built 2 ar9's with palemetto lowers, both had ejection issues. The fixed ejector had to be bent and straightened for them to work. Standard carbine spring and 8 oz 9mm buffer

Rudy, the mad machinist over on ar15.com helped me with those. He owns macon armory and is the ar9 guru

Had a friend over tonight and we discovered the fixed extractor had wear on one side. We had to bend and straighten it to the carrier and we got brass extraction. Took a couple tries. I did not do anything to the spring yet.

The ejector has to be as close as possible to the top of the bolt and in the center of the slot. Your carbine spring should be fine. The face of the ejector should be square, if it's angled file it square.

I agree with the others. Your buffer and spring should be fine. I run a standard carbine spring with a heavy buffer in mine, you need to run a heavy buffer with most 9mm systems (blowbacks at least). I wouldn't touch the buffer spring. It would seem that the ejector is your issue if you are having problems, especially if it has wear on it. The 9mm ARs can be a little janky, but once they are running, they are a blast...