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View Full Version : FIX: 9mm AR running like a CHAMP


NYY
06-15-2012, 11:48 AM
so i just put together the CMMG upper to my CMMG 9mm dedicated lower. i put in a 10 round Uzi mag and manually cycled a full mag through it. about 3/10 round would do THIS. i looked in the chamber and the rounds that jam are ANGLED up a little bit before the bolt pushes them forward (thus causing the jam). WHY? are there anti tilt functions for 9mm AR mags? with the ones that are getting jammed up, they are being pushed forward on their sides, not from the back of them... and yes the rear is on backwards....noted, after a long night of assembling
http://i1086.photobucket.com/albums/j446/LAcatLA/llllllllll002.jpg

http://i1086.photobucket.com/albums/j446/LAcatLA/llllllllll001.jpg

http://i1086.photobucket.com/albums/j446/LAcatLA/9mm.jpg

russ69
06-15-2012, 12:02 PM
Test fire it first.

SocomM4
06-15-2012, 12:07 PM
Too much spring tension in the mag?

clutchy
06-15-2012, 12:12 PM
your rear sight is on backwards...

It seems if you took the same care putting that thing together as you spent paying attention to the rest of the rifle i'm not surprised it's not working.

NYY
06-15-2012, 12:17 PM
your rear sight is on backwards...

It seems if you took the same care putting that thing together as you spent paying attention to the rest of the rifle i'm not surprised it's not working.

really? already comin off as a dick? wow

chillincody
06-15-2012, 12:19 PM
Idk whats wrong just wanted to say thats a very nice looking gun ya built there :)

Merc1138
06-15-2012, 12:20 PM
really? already comin off as a dick? wow

Well it is a possibility considering that your sight is on backwards.

The other thing to consider is what russ69 said and go fire it instead of manually cycling it(and put your sight on the right way). You can't cycle it as fast as actually shooting it would, and it doesn't cycle as slow when firing as it does when you manually do it.

NYY
06-15-2012, 12:24 PM
Test fire it first.
Well it is a possibility considering that your sight is on backwards.

The other thing to consider is what russ69 said and go fire it instead of manually cycling it(and put your sight on the right way). You can't cycle it as fast as actually shooting it would, and it doesn't cycle as slow when firing as it does when you manually do it.

yeah alright sounds good. will do and shall report back with results

MikeR
06-15-2012, 12:30 PM
Way to go full D-Bag clutchy, very useful. :rolleyes:

Did you cut your own mag catch? My 9mm AR was doing something like that because I cut the mag catch wrong by a few mm. I actually used measurements I found online, the good thing is I only jacked up one mag. If you are cutting your own mag catch on the mag let me know and ill explain how I did mine.

tuna quesadilla
06-15-2012, 12:34 PM
I noticed something other than the rear sight that is also installed backwards.

clutchy may be on to something...

But to answer your question, I'd bet you $5 right now that it will work just fine when you actually test fire it, with known good ammunition. Hand cycling isn't a true indicator of function.

USP
06-15-2012, 12:50 PM
i have 2 9mm ar's. both have problems feeding if you cycle it slow. let the bolt go home on its own from the rear and see if it still does it. Slowly letting the bolt go forward will jam mine everytime.

tuna quesadilla
06-15-2012, 12:57 PM
USP raises a good point too. When you say "manually cycling" do you mean your hand is on the charging handle the entire time, backwards and forwards? On pretty much any firearm you should pull the bolt/charging handle/slide fully to the rear and then completely let go to let it slam home.

seainc
06-15-2012, 1:02 PM
I have similar issue with my CMMG 9mm when I try to manual cycle it then I went to shot it went thru 200 rds not a single FTF or FTE. Shot it!

Some Guy
06-15-2012, 2:03 PM
Saying dumb stuff like "sup wit dis" makes my guns fail to feed as well.

NYY
06-15-2012, 2:30 PM
i pull the charging handle back 100% and LET GO. usually 3/10 of the rounds in the mag are angled up slightly, when i LET GO, i watch it jam. doesnt happen when the rounds are sitting straight. but, a test fire will be the only answer!!! SUP WIT DIS ;)

TZL
06-15-2012, 3:15 PM
Cycling with live rounds? Wow

Go spend $5 on some snap caps

ott1
06-15-2012, 6:07 PM
Cycling with live rounds? Wow

Go spend $5 on some snap caps

Save some money. Remove firing pin. Much easier.

duc748bip
06-15-2012, 6:40 PM
Please! No live round even if you think you took the firing pin out. If you forgot to put it back, it's going to a frustrating range trip. Even worse if you forgot to take it out. An Negelgent discharge waiting to happen. To OP of its a dedicated 9mm upper and lower and you function the LPK in installed correctly. Take it to a range and shoot it.

Donk310
06-15-2012, 7:09 PM
your rear sight is on backwards...

It seems if you took the same care putting that thing together as you spent paying attention to the rest of the rifle i'm not surprised it's not working.

There's alway one. Today it's you.

crazychinaman
06-15-2012, 7:30 PM
When you try it out for the first time.Use good ammo,not wolf.The 9mm Ar's like hot loads better.Do you have the right buffer and spring.?Also lube it very well.

russ69
06-15-2012, 8:14 PM
Save some money. Remove firing pin. Much easier.

Doesn't the firing pin keep the cam pin from rotating too far or something like that?

clutchy
06-15-2012, 8:59 PM
really? already comin off as a dick? wow

sorry the ghetto brings it out :(


I'd just go shoot the stupid thing.

also you bought the wrong magpul VFG... there's one specifically made for the MOE handguards.

clutchy
06-15-2012, 9:00 PM
There's alway one. Today it's you.

acknowledged and accepted. :o

ryno066
06-15-2012, 9:06 PM
sorry the ghetto brings it out :(


I'd just go shoot the stupid thing.

also you bought the wrong magpul VFG... there's one specifically made for the MOE handguards.

Just cant keep the IE out of you. :p

clutchy
06-15-2012, 9:25 PM
Just cant keep the IE out of you. :p

:)

:stupid:

m03
06-15-2012, 9:44 PM
1) Try a different magazine.

2) Buy snap caps.

tuna quesadilla
06-15-2012, 11:50 PM
There's alway one. Today it's you.

I see four distinct issues with the rifle, each one being a rookie mistake that somebody who knows the AR15 platform would not make. He may have chosen a blunt way of saying it but he has a point -- it's obvious that this rifle wasn't exactly put together by a master gunsmith.

SocomM4
06-16-2012, 12:09 AM
I noticed something other than the rear sight that is also installed backwards.

clutchy may be on to something...

But to answer your question, I'd bet you $5 right now that it will work just fine when you actually test fire it, with known good ammunition. Hand cycling isn't a true indicator of function.

I see four distinct issues with the rifle, each one being a rookie mistake that somebody who knows the AR15 platform would not make. He may have chosen a blunt way of saying it but he has a point -- it's obvious that this rifle wasn't exactly put together by a master gunsmith.

I spy, a backward sight, a backward trigger guard,Backward castle nut...whats the 4th?

tuna quesadilla
06-16-2012, 12:13 AM
I spy, a backward sight, a backward trigger guard,Backward castle nut...whats the 4th?

The sight is way too far forwards too... ALTHOUGH, looking at the location of the crossbolt... I think it might actually be in the rearmost slot, it just looks so far forwards as a consequence of being backwards.

And he used an RVG instead of an MVG.

NYY
06-20-2012, 1:12 AM
fixed sight... not too far forward... fixed castle nut... not backwards trigger guard... and wrong fore grip? awesome? it fits fine for me...

CHS
06-20-2012, 8:05 AM
Doesn't the firing pin keep the cam pin from rotating too far or something like that?

There's no cam pin on a 9mm bolt

clutchy
06-20-2012, 8:31 AM
fixed sight... not too far forward... fixed castle nut... not backwards trigger guard... and wrong fore grip? awesome? it fits fine for me...

glad you got it sorted; have you shot it yet?

chead
06-20-2012, 8:33 AM
Who cut the Uzi mag? You have to be pretty precise. Anything more than about a 1mm slop and it's not going to feed.

NYY
06-23-2012, 8:47 PM
havent shot it yet. going tomorrow. and as to who cut the mag, i couldnt tell you.

Gatotsu77
06-23-2012, 9:53 PM
I came here to address my concern that the OP was riding the charging handle while chambering each round, causing these hang-ups. (though it seems a few have already addressed this) Bring it all the way back, and let go of the damn thing. (or, use the bolt-catch to stop it all the way back, and smack it to chamber a round) Manual cycling where you impede the ability of the action to work at its normal operating speed can cause hang-ups like this.

I won't preach about the live rounds.. but ideally yes, you ought to get some snap caps.

NSR500
06-23-2012, 10:28 PM
Rookie build... That's the issue.

Falstaff
06-24-2012, 4:27 PM
i cut my first uzi mag per the diagrams on arfcom's 9mm stickie and that failed miserably, i re-welded and re- ground the cut a little higher and it worked better but still jammed alot. These really need to be modded on a milling machine to be reliable i think. I think you should get a cproduct or colt mag and try that as this is almost certainly a magazine problem

I wonder if theres anyone out there that could mod uzi mags fer small fee? The ar in 9 mm is an absolute blast to shoot btw

NYY
06-24-2012, 5:24 PM
no rookie-ness here WHAT SO EVER. THIS BABY SHOT FLAWLESSLY. 150/150 rounds. no issues. love it! actually, now that i mention it... the trigger didnt set on about 1-2/10 rounds. i had to push the trigger back out then pull it. any idea?

NSR500
06-24-2012, 5:51 PM
Right...

Your hammer won't even reset 100% of the time.

:shifty:

Full Clip
06-24-2012, 6:00 PM
Go spend $5 on some snap caps

Yes, these. (http://www.stactionpro.com/9-mm-action-trainer-dummy-rounds-p-1.html)

You have a "dedicated" 9mm lower, so you don't have a mag block in there?

I have a Hahn mag block in my 9mm and it requires a little finesse in placement and locking down for the mags to feed perfectly.

NYY
06-24-2012, 7:11 PM
9mm dedicated lower. no mag block. and yes its like 95% of the time

CHS
06-25-2012, 8:58 AM
no rookie-ness here WHAT SO EVER. THIS BABY SHOT FLAWLESSLY. 150/150 rounds. no issues. love it! actually, now that i mention it... the trigger didnt set on about 1-2/10 rounds. i had to push the trigger back out then pull it. any idea?

It sounds like your disconnector spring is in backwards.

seainc
06-25-2012, 10:30 AM
+1. Fat end goes into trigger

http://i614.photobucket.com/albums/tt228/yen10579/Forum/46f304ff.jpg

clutchy
06-25-2012, 11:56 AM
no rookie-ness here WHAT SO EVER. THIS BABY SHOT FLAWLESSLY. 150/150 rounds. no issues. love it! actually, now that i mention it... the trigger didnt set on about 1-2/10 rounds. i had to push the trigger back out then pull it. any idea?

easy there cowboy; how about a reality check?

hammer not resetting is not flawless.

also you are a rookie and you made rookie mistakes...

BUT you came on here seeking wisdom and now hopefully have it. We're sometimes hard on people because we don't want anyone getting hurt. That includes you.

absorb the rookie, learn from it and come out better on the other side.

enjoy your rifle :)

NYY
06-29-2012, 9:18 PM
easy there cowboy; how about a reality check?

hammer not resetting is not flawless.

also you are a rookie and you made rookie mistakes...

BUT you came on here seeking wisdom and now hopefully have it. We're sometimes hard on people because we don't want anyone getting hurt. That includes you.

absorb the rookie, learn from it and come out better on the other side.

enjoy your rifle :)

i want to make this my like signature/life message haha. i love it. thanks man and no worries. i didnt take it personal at all haha

NYY
07-16-2012, 8:21 PM
oh well guys.... cant even fix the trigger now ANYways.... just stripped the stupid little screws for the KNS pins..... yayyy me

tuna quesadilla
07-16-2012, 8:28 PM
Sounds like you are just not having a good time with this thing. How did you strip the screws?

clutchy
07-16-2012, 9:26 PM
oh well guys.... cant even fix the trigger now ANYways.... just stripped the stupid little screws for the KNS pins..... yayyy me

KNS pins are gangster.

NSR500
07-16-2012, 10:37 PM
Jebus... The rookieness continues. How the heck someone strips KNS pins is beyond me. :facepalm:

joelogic
07-17-2012, 6:22 AM
This thread/build are full of fail.

818gtiguy
07-17-2012, 6:26 AM
This thread/build are full of fail.

Haha...Hack at work..

NYY
07-18-2012, 12:00 PM
haha hey, this thing is running like a boss. the small screws are so weak!!! they stripped just like that. dont yall worry about me and my build... its running awesome

Sunday
07-19-2012, 7:05 AM
I spy, a backward sight, a backward trigger guard,Backward castle nut...whats the 4th?: I myself would thank you for the constructive criticism,and appreciate it. :)

bonesurf
07-19-2012, 11:17 AM
On that note ....turners is selling JR AR9 for 720 now

duc748bip
07-19-2012, 11:37 AM
Every build is a learning process, I only care if he keep his finger off the trigger and the barrel is pointed in the safe direction (and also know the wacky CA gun law...)
There is nothing wrong with asking question here.
My AR 9mm IS running like BOSS! CMMG upper, ramped bolt, RRA mag block, and Giessele trigger. but i'm still looking at Hahn top loading mag block.
This build will never end. :D

jingerale
07-19-2012, 12:33 PM
+1. Fat end goes into trigger

http://i614.photobucket.com/albums/tt228/yen10579/Forum/46f304ff.jpg

thanks! learned something today.

MikeR
07-19-2012, 3:50 PM
....but i'm still looking at Hahn top loading mag block.
This build will never end. :D

Just buy a Double Diamond 9mm lower and be done with it. :D

JSE upper
DD 9mm lower
CMMG ramped

http://i451.photobucket.com/albums/qq234/MRibz/Firearms/Untitled-5.jpg

NYY
07-24-2012, 12:20 PM
went to the range other day... didnt have the trigger problem once out of 100 rounds so.... im cool with it

bonesurf
07-26-2012, 7:46 PM
Inspiring me to post my AR9 build. I tried to cut corners admittedly where I didn't think it would matter or where I couldn't wait to find a good deal. It's working surprisingly well given that I seem to read that AR9 is "sensitive". Course I've only put a few hundred down range with it.
http://img.tapatalk.com/c6e4d81a-0d83-7904.jpg
LW15 lower (laying around riflegear 100)
9mm rra buffer (20 marketplace)
Kns pin set (27--insurance against the poly lower)
Promag magwell. (40. So far so good but this is part I am most worried about)
$190 for whole lower

BCM "blem" upper (90 shipped)
JSE 16" SS barrel (105)
YHM FF mid length (70 marketplace)
CMMG ramped bolt (140 I think CTD)
CH laying around
A2 9mm style hider (5)
Raddlock (laying around)
About 400 for upper--granted not any cheaper than say a JSE upper but free float and setup more the way I prefer

BUIS and optics are "extras" laying around

I did have to shave the hammer down despite the ramped bolt. Nice thing about a plastic hammer--easy to see marks where the problem is. I picked up on this before I shot it. I may change out to a standard trigger group I have laying around.

I splurged and added a barrel shroud but thats just cosmetic. ASC mags working great. They are what seem to be easiest to find used. So far I've been shooting reloads no problems at all. I know there's a lot of hate for promag and LW15s but seems to work

nyc71
07-27-2012, 12:30 AM
Bonesurf, which barrel shroud did you use?

bonesurf
07-27-2012, 5:56 AM
Bonesurf, which barrel shroud did you use?

Usmachinegun (i think) fake suppressor. Threads right on to the barrel. Course now I lose the nice SS barrel look lol.