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Discussion Starter · #1 ·
I've got an AMD-63. I measured the notch in the front trunnion that the bolt slides on it is mic's out at .280. On the ACE website, 762 used a letter "C" bit to space from the top rail down to the position of the lower rail. If the gap in the front trunnion is .280...top edge lines up with top rail, shouldn't the bit be something more like a "J" or "K"? I base all of my measurements and predictions off an AMD-63. I think he built an AMD-65. If there are differences in the trunnion, I could understand the differences in bit sizes. But if they're the same trunnion and I'm also using an ACE blank what's going on? Other observations would be greatly appreciated!
 

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yosuthnmasa said:
I've got an AMD-63. I measured the notch in the front trunnion that the bolt slides on it is mic's out at .280. On the ACE website, 762 used a letter "C" bit to space from the top rail down to the position of the lower rail. If the gap in the front trunnion is .280...top edge lines up with top rail, shouldn't the bit be something more like a "J" or "K"? I base all of my measurements and predictions off an AMD-63. I think he built an AMD-65. If there are differences in the trunnion, I could understand the differences in bit sizes. But if they're the same trunnion and I'm also using an ACE blank what's going on? Other observations would be greatly appreciated!
Have you tried using the bolt carrier instead of a drill bit for getting the lower rails to align correctly?
 

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The letter C drill bit is recommended as a guide, not as gospel. It doesn't really matter what size bit is used as long as the lower rails are parallel to the top and they are flush with the notches in the trunnion. If J or K works for your rifle, use it. The next build might require a 0.250", I, or 17/64".

Because of the -ahem- "tolerances" of the AK as manufactured by so many different nations, I think you can expect some significant variance in parts and still have interchangeability. If it was an AR-15, I'd wonder where the out of spec parts came from. With an AK, just consider it to be "reliability insurance".
 

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Discussion Starter · #4 ·
I think I've confused myself a little. The letter "C" should work perfect, after I made some more measurements and took a break for a while. Thanks guys!
 
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