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AMT Backup; feeding problems

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  • AMT Backup; feeding problems

    I recently sold an old but little used stainless AMT Backup to a co-worker and it's been giving him feeding problems.

    He's using all jacketed ammo ( no lead or JHP ) but they occasionally ramp upward...not a full stove pipe like situation but
    sounds more like hitting the ramp, bouncing and getting caught by the slide as it goes into battery.

    Any thoughts?
    Len

  • #2
    Is this the .380 or .45?
    I have the same problem with my .380. I've tried several different magazines from various manufacturers, and the ProMag seems to work best, but still does the same once in a while. I'm going to start messing with the follower to see if I can tweak it. It seems like the very tip of the follower is too tall.
    But then again, I've heard just about anyone that has/had one of these with the same problem, so probably a very basic poor design that may be hard to overcome.

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    • #3
      Yes, .380.
      Please post back if you have any success but it does seem endemic.
      Thank you.
      Len

      Comment


      • #4
        I don’t know much about those specific guns, but the issues you describe are usually caused by magazine feed lip problems. That would be the first thing I would check.

        Similar problems can be caused by weak ammo which fail to push the slide back with authority and as it returns to battery, it wimps out because it didn’t get a good enough head start. Or it wimps out because of a weak return spring, dirty or tight fitting slide or lack of adequate lubrication causing more drag than necessary.

        But I will vote with “rubes”, it’s the magazine.

        Comment


        • #5
          Don't forget the importance of the shooter's grip. If the gun functioned well, and there has been no change but the person shooting, a weak grip can have an effect on function.
          Jim H.

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          • #6
            I’m with Ron on the feed lips. Too tall, too wide a gap, or too low will all do it. If follower or mag spring usually it would run well at some point in the round count, starts out well then jams or jams at first then runs well.

            To start getting an idea what is going on try holding up on the mag and see if it runs then shim it down and see if you can make it run. From that you should be able to work out what to do to the lips . . . Provided there’s enough meat there to do anything.

            Could also be the limp wrist, ammo, or slide spring . . . Tricky to run this stuff down sometimes.
            Anybody that thinks they know it all doesn’t even know enough to understand they know nothing!
            Andy

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            • #7
              I guess I am putting too much faith in new manufactured mags.
              when I got this, it already had a polished ramp. I re-polished it to a fine finish. Totally stripped, cleaned and lubed it up and still same. I did not change the recoil spring like Ron suggested though. then I got brand new mags. The ProMags and another brand (cant remember), two of each. With the ProMags, I can SOMETIMES go thru the entire mag with no problem, but very rarely. I think my grip should be OK as no issues with any of my others from 22's to 1911's. Tried lots of ammo, from CCI, Blazer, PMC, Magtech.
              I'll take a closer look at the feed lips and try C_Lazy's suggestions. I didn't put too much effort into it after the first go round, Then gave up a few years ago. But I think this would be a nice piece if it could be made consistent.

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              • #8
                Seems to me I remember that the early AMT's required a special grease on the slide rails. I know the Hardballers did. The post mentioning lubrication jogged my memory. That was the main reason I didn't buy an AMT back in the 80's. Your's might be an improved version.

                Mike

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                • #9
                  Mine is long gone, but, the only time I ever had feeding problems was when I limp wristted it or fed it anything other than ball. IF I used hollow points I had to make sure I had a rigid grip.

                  Only complaint about the gun was the straight up eject. Brass would always hit just above the shooting glasses.

                  Comment


                  • #10
                    Have you tried different ammo? I had a similar problem with a cheap Federal Ordinance 1911 copy with some Remington .45 ACP once. I thought it was the gun and polished and tweaked for a few weeks before I realized it was the ammo.

                    Turns out that particular batch of ammo had the case mouth still slightly belled. When the brass tried to cam over the feed ramp to get into the chamber the case mouth would hang up on the top of the chamber. I ran all that ammo through my seating die to close the bell up a little more and the problem went away.

                    Jeff

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                    • #11
                      I recently was asked to look over an OMC .380 back up that had feeding problems. I was not impressed with the weapon and, frankly, it struck me as the true definition of a "Saturday Night Special"! The owner was using, or trying to use hollow points which was part of the problem. The other finding was that the ramp was as rough as a cobb. I didn't take a dremel to it, but I did use some emory on the tip of a finger to clean up the roughness. Thus far it appears it is functioning well, provided ball ammo is used.
                      John B

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                      • #12
                        You need to open up the feed lips of the magazine so that the round is presented closer to the centerline of the barrel. AMT actually recommended this in the owner’s manual! It works but it always amused me that a company would tell me to take a pair of pliers to their products and good luck. They recommended Break Free CLP as the rail lube. AMT was a local company to me and there were a lot of colorful stories about it. One of my favorites was that AMT had the barrels welded to the frames by the students at the local welding school. This weld cracking is the most common failure point on the gun.
                        For your amusement I found and posted this screen shot from a manual I have.
                        Good luck, Mike
                        Last edited by mf205i; 02-10-2013, 07:02 AM.

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