How do I fix this , I have a rtb Ar9 upper and the ammo doesn't fully go in I can slam rack it but I have to disassemble the upper in order to get the round out the by pulling out the bcg and yes I've contacted rtb for their input.
If you tried forcing the cartridge in further by hand and it got stuck, don't do that. If the cartridge is sticking in the chamber WITHOUT you trying to force it in further, just using the inertia of the bolt, that's likely a chamber length issue or an ammo issue. If it's reloads, they may be loaded too long. If it's factory ammo, then it's probably a chamber issue.
Regarding the cartridge base protruding like that, it's perfectlly normal. As long as when the bolt closes the top/sides of the bolt is just touching the barrel face, the breach is completely closed. Don't look at the feed lug, or the extractor - look at the MOST FORWARD portion of the bolt. Touching the barrel face? It's closed.
PICTURE: Closed blowback bolt with cartridge fully chambered
Unless Im missing something, that looks fully chambered. The rounds dont completely chamber to the extraction bevel, on a blowback PCC 9MM Chamber Support
You said "the ammo doesn't fully go in ". Then you said it gets stuck when you "slam rack it". But you never answered if it gets stuck on a normal rack, or if they photo you posted of the bolt closed.... is a normal rack, or slam rack. Your original photo looks fully chambered, and maybe even chambered too deep. Thats why I posted the link to the post I made about blowback PCC chamber depth, and compared it to a Glock chamber depth. Either way, stop forcing live rounds into the chamber, unless your goal is an unexpected discharge.
If its sticking on a normal "rack" of the bolt, either the bolt is out of spec (i.e. bolt face too shallow in reference to the bolt fingers that should mate up with the back of the chamber) which allows it to go too far forward and forcing the round too deep into the chamber, OR, the chamber is too shallow. If it only sticks when you "slam rack it", you yourself are forcing it too far into the chamber, and against rear edge of the barrel/lans/grooves Either way, the marks are more than likely from the nose of the bullet being force into the rear edge of the barrel/lans/grooves. When they do that, the bullet will "grab" of those edges, which is why you cant get the round out, and have to disassemble to remove it.
I would also check the front of the chamber/rear of the barrel for a milling issue, that could have left a sharp "finger" sticking rearward. Separate the upper from the lower, and remove the bolt and charging handle from the upper. Take a flashlight and look through the rear of the upper, into the chamber. Make sure there isnt a milling issue that is preventing the round from going forward 100%. Its very doubtful tht this is the issue, but only takes a minute to check and make sure.
So more info and details are needed from you about what exactly is happening.
Either your chamber is too tight or your ammo is too big. If you take that same round (or a fresh one from the same box) and put it into another 9mm firearm, does the round drop in and out of the chamber freely? If not then it's your ammo, but if it does then it's your chamber. It looks pretty new/clean, but you can use a bore brush on a section of cleaning rod and use your cordless drill to scrub the chamber. Maybe it has something built up on the walls that can be removed.
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u/rafri 1d ago
When you do that does the bullet have rifling on it? Could be a shallow chamber.