AR9 Help

[Grogmister]

I built an AP EPC AR9 recently but I have an issue and need some help. AP matched upper and lower, Faxon barrel and BCG, Kaw Valley 7.5oz buffer with .308 spring. I now have 50 rounds down the pipe and the bolt hold open locks back with 1 round left in the magazine every time. I have tried 3 different magazines including a Glock OEM as well as 2 different brands of ammo. If I drop the magazine, put it back in and drop the BCG it then FTF the last round and compresses the projectile into the casing. Anyone have an ideas what the issue could be or where to start? I know if I email AP they will say it’s because I’m not using all AP parts or the buffer is only 7.5 oz instead of the 7.7 oz they recommend. I can’t see how either could be the issue but anything is possible. Thanks for the help!

 

[gmcttr]

...I know if I email AP they will say it’s because I’m not using all AP parts or the buffer is only 7.5 oz instead of the 7.7 oz they recommend. I can’t see how either could be the issue but anything is possible. Thanks for the help!

Call AP and talk to them. It may be as simple as the last round hold open rod/wire on the upper receiver is actuating the bolt stop too soon and needs a little tweaking.

 

[Grogmister]

Thanks I will give them a call.

 

[Grogmister]

talked to AP. They suggested using a Mapul magazine because it has a bigger notch on the front left of the follower. So once I get a Magpul one we shall see if that works. Black pic is OEM Glock and orange pic is Magpul.

 

[gmcttr]

I appreciate the updates. I still have LOTS to learn.

 

[Grogmister]

I appreciate the updates. I still have LOTS to learn.

You and me both. It worked perfect with the Magpul just now. I will eventually try to make the other follower match the Magpul one. Surprised me but it actually was the issue.

 

[gmcttr]

You would think if it was designed for Glock mags, that it would run on Glock mags.

 

[Grogmister]

You would think if it was designed for Glock mags, that it would run on Glock mags.

Yes one would think but apparently Magpul is better.