Put together an AR9 with a 16" PSA upper/bolt, S&W lower receiver, Franklin Armory BNSF III trigger, Endomag insert for pmags for the ejector and feeding into a 5.56 lower, KAK 8.4 ounce buffer, and the replacement buffer spring from Franklin Armory for the trigger. In single shot mode it works fine. In binary mode it pushes the bullet down into the case and jams. Would this be because of ****ty Armscor ammo or do I need to break it in as this is the first 30 rounds through the firearm? Also could it be something I need to tune?
-
Last Call Guest on these Group Buy Deal Items from Baja Designs
Issues with AR9
- Thread starter NotmyJK
- Start date
-
- Tags
- outdoor sports recreation
Don.
Radioactive member.
Did you get a pic of the malfunction? Where is the tip of the bullet catching when it’s getting set back in the case?
Lee
Guild of Calamitous Intent
Kind of apples to oranges, mines a Foxtrot Mike 10" upper on a Glock magwell Aero lower, but same trigger with whatever buffer spring the Franklin instructions recommended and a Midway AR Stoner AR9 buffer. I've only used the Korean RWB 33rd mags. I fully expected to have issues from all of the stuff I've read, I mean I selected the parts I did to try and mitigated issues, but still expected some teething. It just works. 🤷♂️
Buffer I have, it's out of stock but backorderable:
www.midwayusa.com
Buffer I have, it's out of stock but backorderable:
AR-STONER 9mm Extended Buffer AR-15 Carbine
The AR-STONER™ 9mm Extended Buffer is perfect for your 9mm AR-15 Carbine. An extended buffer shortens the length the bolt travels and decreases...
www.midwayusa.com
- Thread starter
- #4
I will get some this afternoon
Aisin
Grumpy old ****
- Joined
- May 19, 2020
- Member Number
- 304
- Messages
- 3,278
It’s your buffer spring. Mine was doing that with a .308 spring. The spring from Franklin is an extra power spring. Throw it in the garbage. Extra power springs cause feeding issues. Standard 5.56 carbine spring fixed my issues. I run a KAK 10 ounce buffer. It’s closer to 11 ounces actually. 10.7 ounces. The key to a reliable 9mm AR is to run the heaviest buffer possible. 115 grain 9mm will cycle 43.5 ounces of bolt/buffer weight out of a 16 inch barrel. If anyone recommends a .308/extra power spring disregard them.
Last edited:
FrankenToy
Cynically skeptical...
- Joined
- Aug 6, 2020
- Member Number
- 2431
- Messages
- 664
I run just a standard mil-spec buffer spring in mine, too. Sometimes I run a heavy buffer, sometimes I forget. It's easy to tell when I forget to swap buffers.
Motorcharge
Unregistered User
- Moderator
- #7
How is the feed cone on the barrel? A lot of 9mm barrels don't have enough angle to them on the cone. I switched to a Macon Armory barrel and mine feeds everything I've stuck in it now though I don't have a binary trigger in mine.
- Thread starter
- #8
Replaced the buffer spring with the standard carbine one and ran another 30 round mag. Ran well expt for secnd to last round, the bullet got pinched in between the bolt and end of the charging handle that pulls the bolt back. The bullet did not have the setback like it did before,
- Thread starter
- #9
Single shot is fine. Binary is where all the issues are.
Don.
Radioactive member.
Looks like the spring took care of most of it. The mags are kinda ****y with the ejector and long feeding ramp. I would look into something else that has an actual ejector and places the mag closer to the chamber.
Motorcharge
Unregistered User
- Moderator
- #12
Yeah I know, was just thinking the angle might be fine for a slower rate of fire but the faster rate might be slamming the round into a flat spot. I know on mine when I had the style on the left it would feed fine if I shot slow, but if I started shooting quick it would jamb up the same as yours. I was also using endomags and switched to a glock mag lower the same time as I switch the barrel though so I'm not entirely sure which fixed my feeding issues or if it was both.
Colt style cone on the left, Macon on the right.
gbiddlec
Member
I had the same issue on a QC10 build when using truncated bullets. QC10 ended up relaxing the feed ramp to fix it.Yeah I know, was just thinking the angle might be fine for a slower rate of fire but the faster rate might be slamming the round into a flat spot. I know on mine when I had the style on the left it would feed fine if I shot slow, but if I started shooting quick it would jamb up the same as yours. I was also using endomags and switched to a glock mag lower the same time as I switch the barrel though so I'm not entirely sure which fixed my feeding issues or if it was both.
Colt style cone on the left, Macon on the right.
At this point, I agree the remaining issue for OP is the mags.
![[486]](https://data.irate4x4.com/avatars/m/0/94.jpg?1700178133){kind=avatar}
[486]
smell-o-vision
isn't the bigger diameter feedramp really terrible for case head support?Yeah I know, was just thinking the angle might be fine for a slower rate of fire but the faster rate might be slamming the round into a flat spot. I know on mine when I had the style on the left it would feed fine if I shot slow, but if I started shooting quick it would jamb up the same as yours. I was also using endomags and switched to a glock mag lower the same time as I switch the barrel though so I'm not entirely sure which fixed my feeding issues or if it was both.
Colt style cone on the left, Macon on the right.
picked up some brass from a guy shooting an ar9 and they all had some tremendous bulging going on, when cut in half they've got a good mm or so between the beginning of the chamber (well, the deformation) and the end of the case head
Don.
Radioactive member.
It’s not going to be any worse than an open bolt subgun. You should see some of the **** my Uzi spits out. I used to reclaim it all for reloading. I have so much brass now that anything that goes through the subguns gets scrapped. It can be reloaded, but the bases swell enough on some that they won’t chamber in my other 9’s. They are fine to use in the MG’s though.
Norm
Newb
I had to run an extra power hammer spring on my AR with the Franklin trigger. I was getting light primer strikes at times.