9MM AR-15 style Carbine Build Documented

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  • erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    My biggest complaint about my 9mm carbine is loading a 32 round colt mag by hand. Boy was that painful and slow. I went online and found this at brownells:

    WOW!!!! It is increadible. Works like magic.
    They are indeed like magic... I use unmodified Uzi mags in a few of my guns, and the LULA saves your thumbs like nothing else. If you ever get into pistols, the UpLULA is also pretty amazing on some guns with very heavy mag springs.

    What ammo are you using for your testing?
     

    Kramer

    Rights Abused
    Jan 26, 2016
    57
    Baltimore
    They are indeed like magic... I use unmodified Uzi mags in a few of my guns, and the LULA saves your thumbs like nothing else. If you ever get into pistols, the UpLULA is also pretty amazing on some guns with very heavy mag springs.

    What ammo are you using for your testing?

    Mostly 9mm Luger Speer Lawman 115 grain TMJ, but also tried some hollow point ammo: 9mm Luger Federal Classic Hi-Shok 115 grain JHP Hollow point.

    I indeed just got a CZ 75 and have a maglula for its mags as well. Don't think I could load 17 rounds without it.
    -Kramer
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    That's relatively peppy ammo you're using... I doubt it's short-stroking. As usual, I'd do what Chad says.
     

    Kramer

    Rights Abused
    Jan 26, 2016
    57
    Baltimore
    Update on FTF Issue

    I had some time to work on the carbine this weekend and test fire it. So it seems that the most likely explanation for the failure to fire is that the trigger is not cocked because the bolt moves to fast when it is pushing on the hammer. I really don't want to replace the trigger because I love its feel. So my logic said I should try to make bolt stay over the hammer for a longer period of time. The Spikes buffer I have is so long that it bottoms out in the buffer tube when the bolt is just clearing the bolt catch. So the only way to get it too back up more is to either get a longer tube or shorten the buffer. Longer tube would be a problem. So I decided to shave off some of the bumper on the back of the buffer with a razor blade:



    I figured that it would not miss the 3/16" or so I cut off. It still had some padding and I could always replace it with some spares if I needed to.

    Took it to the range with Gambler and we stuck a mag in and started firing with hope...it FTF on 5th round :banghead:. We carefully (with gun pointed downrange entire time) split the upper and lower to see the state of the trigger. The hammer was forward confirming that it did not get cocked.

    At this point decided to switch back to my shorter "carbine" buffer. We had brought it with us, so we field swapped it. This time I used $2.25 worth of quarters which put its furthest back position about 3/8" aft of the bolt catch. And this time it has the new flat wire spring. I figure that I really want it to be reliable and I would rather break another bolt catch than have the current state.

    Went on to fire about 175 rds through with zero problems. So it looks like this solved the hammer cocking issue at least. Bolt catch looks fine for now. I figure if bolt catch breaks again, I will just remove it and use the gun without a catch. A little inconvenient, but really not a problem.

    When I got home I noticed that the foregrip was loose. I had kind of fudged the fastening of it to the barrel nut. Today I took it off completely and worked on making it right. The problem was the holes to fasten it to the barrel nut were a little too far towards the muzzle so the screws had a hard time going in straight. I used a round file to enlarge the holes towards the stock end and this time fastened it with all 6 screws (I had left the bottom 2 screws off before) , no washers (used lock washers before) and locktite. I cranked down hard tightening them. It seems very firm now so hopefully it will stay that way.

    Also got the bug to put a cheap scope on the gun, so ordered this Ohuhu Red/Green Dot Sight from Amazon. Figure it is worth the gamble for $30. Will report on it once I get it installed and tried out.
    -Kramer
     

    Kramer

    Rights Abused
    Jan 26, 2016
    57
    Baltimore
    Also got the bug to put a cheap scope on the gun, so ordered this Ohuhu Red/Green Dot Sight from Amazon. Figure it is worth the gamble for $30. Will report on it once I get it installed and tried out.
    -Kramer

    Was reminded that I did not "report" as I said I would. I got the Ohuhu sight and installed it, removing the iron sights. It mounted easily and looks to be made well. Still not 100% happy with its adjustments; need more time on the range to do that.

    It seems to work very well but has one issue. The "dot" is not in fact a dot. It is sort of smeared out to be an oval that is not as precise as I wish it to be. At 75 feet the smear covers a couple of inches. There is a brighter part of the smear which you can aim for, but clearly it could be better. For $30 I can't complain. I can definitely put a pretty tight group at 75' with the sight.

    I also bought a cheap magnifier to go with the sight. I finally took it off. It was not exactly aligned vertically with the sight and made the "smear" worse. I tried shooting at 100 yards outdoors and did not feel like the magnifier helped at all.

    The carbine is working well now. No problems with the bolt catch. Probably put 400 or more rounds through it. I am very happy with it.
    -Kramer
     

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