Tips on building a reliable 9mm AR-15

Hi, Thank you for this video – nice job and setup. Am seeking any info you may share on this issue. Have built a 9mm AR pistol from miscellaneous parts. It runs, but has some reliability issues after firing – sometimes the extractor seems to miss the casing notch, and the fired casing stays in the chamber. It's inconsistent – sometimes casing extract and other times not – both occurring within a single mag and across various types of rounds. Have bench checked manually with upper only, and the same issue occurs – I may need to push the bolt forward several times, before the extractor catches and pulls the casing back. Same occurs with expended and live rounds. Have removed/cleaned extractor and tried other extractor with same result. Am leaning toward diagnosis of the elusive head space issue – that either the bolt face or barrel rear surface need a few thousandths removed so the extractor can consistently engage the case notch. Interested in any feed back or experience that may relate. Thanks,

Nice job you will only get better .

It’s going to be for home defense. It’s not wise to fire 556 in the city and apartments

What work s best colt mag set up or glock with mag new insert

What barrel you got. I seen one with a ramp. Barrel but it cost $170. Or a $79 is good buy

Have you tried out any of the combo buffer + spring products in your 9mm AR? I just finished building mine and even with a stronger spring and 10oz buffer the recoil is on par with my 300 blk AR shooting supersonic. Just curious if you'd tinkered around trying to soften the recoil.

How much was your set up minus the suppressor?

Well done sir, thanks for the info!

I'm in the process of getting parts together for a 9mm AR build. What has been your long term opinion on the 10oz buffer + standard spring combo? I am going with a dedicated 9mm Glock mag lower, 5.5" barrel and have ordered a 10oz buffer (at least to start things off). Do you think that weight is appropriate given the short barrel or should I anticipate going lighter? Just trying to collect info as there doesn't seem to be any solid consensus on 9mm AR configs. I'd like to avoid…collecting too many parts in the trial and error process.

Nice ar9 my setup is

Angstadt jack 9 reciever set
QC10 3.5” barrel
SLR 4.75” rail
TAccom extreme BCG
Spikes 7.7Oz buffer weight
Spikes buffer spring
SBPDW brace
BCM enhanced LPK
Magpul pro flip ups
Sig Romeo 5

Fantastic video

What do you think about Palmetto State armory complete 9mm ARs?

Taccom aftermarket ar9/ar45 feed ramps for $20 fix the hollowpoint (or any) feeding issue. They work great in my ar9/ar45! chk it out

nice build~! good info~

Colt looks much cooler, mag is not canted…. glock reminds me of lame sunglasses, like Oakley razorblades…
Colt is cool, like 60's black wayfarers….

Josh,
How does the lighter spring/heavier buffer work unsupressed? Or do you have a different setup for Supressed–Unsupressed?

Thx
MJ

I had the same problem with the nose going downward. Taccom3g has a stainless steel deflector that redirects those nose down feed problems up into the chamber, both round nose and hollow points. you have to file some upper receiver next to the barrel face. I used an ignition point file from oreilly's. Just follow the instructions they send with the defector. They say to friction fit or glue it in place, I chose to keep it barely loose so I can thoroughly clean the upper. If I were to take the upper and lower apart it would fall out.

What buffer tube are you running with that shockwave? Looks a bit longer then my basic one that xame with a kit.

thank you for sharing your experience

Just file that lip down a little bit.

Try a taccom feed ramp. it will help with the hollow points. https://taccom3g.com/product/taccom-glock-lower-feedramp/

I have a feeding problem with my ATI Milsport. I use ETS and Glock mags but still have the same problem every other round. someone says it could be the mag but as you have mentioned may be to replace with lighter spring and heavier buffer? Please help

Best barrels are macon armory, he will also do your barrel if u don want to buy one

Thanks for the tips sir

For my buffer set up I have a flat wire spring and a hydro buffer. Def reduces over the standard 9mm set up imo. Only problem with it is it’s a pain in the ass to get in and out of the gun.

I've now run black Creek and qc10 Colt lowers with ballastsic advantage and CMMG barrels respectively. Feeds all FMJs and Federal HSTs with zero issues.

Yeah you officially made it too complicated fur me

It's an excellent video, my ar9 it is like yours, only I have the sidecharger model.
I experienced the same problems:
1 the fake "gas key" separeted, easy fix: clean the screws and apply loctite treadlocker.
2 at about 3000 rounds, the original firing pin, snapped in two parts and the head had a mushroom deformation, clear sign of bad heat treatment and probably also bad material.
Now I have a better quality firing pin, always with its spring for safety.
3 the bolt had a sharp corner that caused unusual wear on one feed lip of the ETS mags.
It needed a little bit of filing.
But in general the bolt with the 223 extractor is excellent, way better than the old ar9 projects.
4 some sharp corners around the charging handle needed sanding.
5 the sidecharger handle required tuning, sometimes it didn't stay closed at the last round, the retention detent it's not a great solution, especcially with wear.
But the sidecharger is really handy in competitions, also the working bolt release on last round.

I really like mine, it is extremely reliable and with the awesome ergonomics of the AR platform, even with the minimal tuning I think that it is way superior to many other SMGs/9mm carbines, that also have their problems.
Again great video👍

I have the PSA AR9(stock) that worked great the first few times at the range. I started having feed issues and thought it was the ammo. You think the KAK Buffer will solve those issues? The ammo is "nosing down" like the hollow point ammo you show here.

THANKS BRO!

Thanks for the info! I have the Davidson Defense 9mm Conversion system on the way, and I will be trying it out on a Polymer 80%'er I just machined. Total test bed deal, but should be fun to learn the 9mm AR game. Have fun, G.

Nice build. I have the same buffer set up, and lower. Change out the stock mag release for the odin works model. Its works perfectly. Much better than the stock one.

Great setup bro

What barrel length would you recommend? I don’t run a suppressor. I run a 10.5 on a 5.56 but was wondering when the powder “burnout” in a 9mm case became a hindrance.

great tips on ar9 reliability. just ran 3 quarters w/carbine buffer and nfa buffer spacer worked very well. only 2 ftf w/ets mag stock glock 33 rounder was 100% reliable

This guy is so hot wtf

Did u use mk9 cmmg firing pin?

Nice vid, thxs. These feed ramps add ons will allow any hollowpoints to run in ur glock ar lower. They also have ramped 9mm ar barrels. Chk them out. https://taccom3g.com/product/taccom-glock-lower-feedramp/