Shooting my son’s gun alongside my original Auto Mag the other day, we experienced this same reset issue with handloaded rounds. It has always run fine with new SBR ammo. My handloads run fine in my gun but often wouldn’t work in his. I suspect the new gun has a tighter chamber than mine, and my sizer die isn’t screwed down quite far enough, leaving a tiny bulge at the base of the cartridge the new gun won’t tolerate. We did find that if we chambered the same round several times it would then work, suggesting the chamber was acting like a sizing die each time.
I’m glad the disconnector works so well. It won’t allow the hammer to fall until the bolt has fully rotated into battery. So this reset issue is a feature, not a bug.
Mike - Are you sizing your handloads with a carbide die or are you using a steel die and lube?
@bob-cohee Good question! I’m using a RCBS carbide die, which works the case a little harder, turning the tapered Auto Mag Case into a straight-sided case with a bulge at the bottom.
I haven’t yet tried using a standard steel 44 AMP die. A friend had chambering difficulties with these and wound up using a 270 Winchester sizer die, which shrank the case down just that much further.
I have a small-base 308 die which would likely work even better. But my first attempt will be to simply screw my carbide die down a bit further.
I think that your conclusion that there is a slight bulge at the base of your brass is probably correct.
In my experience, using carbide dies on tapered cases makes this problem worse than dies that return the cases to their intended dimensions.
I doubt that screwing the carbide die down tighter will help. Test size with a steel die and see if that helps the problem.
I'm slapping my forehead here for not thinking of that.
Still cannot find out why bolt will not lock back on last round. My second magazine came yesterday, so I will try it, and see if it is a magazine issue. Almost every time I remove the barrel the accelerator falls out. Although unlikely, I wonder if it is not assisting the rearward travel of the bolt, causing this issue.
It's the magazine. Looks like I have a bad one, that came with the gun. The new one works perfectly. The trouble must be in the extended tab. Looks the same, protrusion measures the same, but it's a no-go. This deserves further investigation.
Lee 44 cal 240 gr RN bullet. Mine weigh out closer to 250 gr.
All powder coated, ready to be sized to .4295. Color is Eastwood Ford Blue.
What for load data are you folks using in your Automags? I had been using 19.0 gr 296, with a 250 gr RN, cast bullet, in formed rifle cases. 1286 fps. I am gradually getting the bugs worked out in mine. Close to 500 rounds fired. Break-in maybe takes a while.
Does anyone have any info on disassembly of the Automag? My bolt catch is binding somewhere. It will activate, when inserting an empty magazine, and retracting the bolt. In firing though, it frequently will not rise fast enough to catch the bolt. I have been trying to remove the snap ring holding the catch in place, but have been unable to do so, even with micro pliers. I have been holding off on using more drastic means. I have so far been unable to determine exactly where on the catch the interference is. But in removing it, I hope to see where the issue lies. This has been an ongoing issue for me. I feel that bolt continuously falling on an empty chamber cannot be good for the gun. Other than the lock back issue, the gun works fine.
@gbertolet I had a similar experience and found the grips were interfering with the latch. Check the inside of the grips and remove material as appropriate to eliminate the binding.
Thanks for the tip. But that was not the cause of my issue. I recently determined that the steel plate under the follower, with the tab, that activates the bolt catch, was flexing downward when contacting the bolt catch. This was limiting the rise of the bolt catch, so fully locking back the bolt during firing was inhibited. My solution was to make up a thicker plate for underneath the bolt catch plate. This greatly reduced the flex, and I get full upward travel of the bolt stop now. I have one picture attached. I will take some others later.
