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Old 11-17-2012, 08:18 PM   #1 (permalink)
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automag double feed

Pretty sure this is a basic question, but I don't know the answer. Basic google search did not give me an answer either.
I have a 68 classic automag. It shoots great with CO2, but when I use HPA, it double fires and a few balls just roll out the barrel. Why this difference? How do I make it work properly with HPA?
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Old 11-17-2012, 11:28 PM   #2 (permalink)
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How does the sear look? Worn sears can cause double fires.
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Old 11-17-2012, 11:31 PM   #3 (permalink)
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????

Air isn't going to make a difference. You probably have a detent issue.
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Old 11-18-2012, 11:39 AM   #4 (permalink)
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I have been reproducing the problem by switching between hpa and co2. Still the same issue. Maybe it is not a double feed. It is a double fire. One trigger pull creates two cycles with HPA.

Is the detent part of the barrel? I see a wire on my barrel that appears to serve the function of a detent.
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Old 11-18-2012, 11:47 AM   #5 (permalink)
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i have not checked the sear because I have hesitated to take it apart.
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Old 11-18-2012, 01:06 PM   #6 (permalink)
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Yes, the wire on the barrel is the detent. The detent won't have anything to do with your valve cycling twice, but it would be the cause of roll outs. The 'newer' detents are plastic. If the sear assembly turns out to be a problem, the AGD store has those as well.
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Old 11-18-2012, 06:29 PM   #7 (permalink)
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Is there a writeup of how to replace a sear?
Thanks.
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Old 11-18-2012, 06:30 PM   #8 (permalink)
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you unscrew the 2 screws holding the grip frame to the gun and the entire gun will come apart.

the sear assembly sits on the top side of the rail, sticking downward into the grip frame to stick out again behind the trigger.

don't lose its little axle.

watch all 9 parts, become expert in 2 hours https://www.youtube.com/watch?v=vehPc7vuK20
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Old 11-19-2012, 10:33 AM   #9 (permalink)
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I think you're looking at that funky behavior that makes people say "my classic valve has RT".

I've always associated it with a sticky on/off, but like ta2maki said, the sear could be involved as well. Basically, you're getting gas into the dump chamber after you let off the trigger, but before the sear can latch up completely.

Since it's more like a performance issue, watch the videos heinous pointed out and look at a few things on your marker in particular;

1) bolt spring length - should be about 1/8" or more over the tip (a little longer is better for this problem).
2) sear tip is not rounded/worn
3) rail bushing in place (always)
4) rear frame screw is snug when assembled
5) on/off pin is .750 (make sure no one has ground it down) and it is free to move.
6) sear pin/axle fits properly (sometimes you find a "substitute")
7) on/off top o-rings in good shape

It's not that you expect to have trouble will all that stuff, it just all needs to fit together and old mags can have a lot of "history". HPA runs at a higher dump chamber pressure than CO2 in the same mag, and it's sneaking by the on/off where the CO2 doesn't.
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Old 11-19-2012, 09:00 PM   #10 (permalink)
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Thank you for the great reply. I am getting ready to take it apart. Just developed a new problem though. The video said that degassing the gun and directly twisting the Co2 tank back into the gun will tear the o-ring. I think that I did this. There is now a huge leak. I will try to fix both problems. Any recommended place to buy parts? ANS?
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