Uh Oh

eldiablo_si wrote: Ok, now I'm a bit confused.  I thought that the little dove-tail on the back of the bolt is what the sear hit?  But what you are saying is it is the little square notch that is approx. in the center of the bolt?  Could you please specify because I though I understood how it worked, but now I'm not so sure.  Thanks for all the help and being patient with me.

Assemble the internals on the right half of the shell and you will see where all the parts mesh together. I didn't intend this to be a photographic quality rendering. Certainly if you have taken it apart you know which is the sear notch!

eldiablo_si wrote: Well after the sear polish job, everything went back together and worked fine.  I went back later and hit the back bolt so that must be the problem.  How much will a back bolt run me new?  I know county has them, but the site is down at the time.

Before you give up on the original rear bolt try going after the sear engagement notch one of two ways.

First let me say that it is still likely that the slightly reshaped sear is probably the primary culprit. But, the double whammy of going after both parts with the polishing brought about the failure. I will make a guesstimate based on personal experience that a few hours of using that slightly reshaped sear against the stock bolt notch would have brought about failure the same failure. These parts fit together much better than you think they do. If you buy a new rear bolt, you really need to install an new sear at the same time.

Now, back to "fixing the bolt." Mount the bolt in a vise to hold it steady then take a good sharp (new blade) hack saw and take a few steady smooth strokes in the notch to deepen it ever so slightly and to alter the angle just a bit. That is, tilt the blade ever so slightly so that rather than the cut being at a right angle to the horizontal plane of the bolt (straight down) it cuts to the rear slightly to create a slight notch or hook shape to the groove. The picture blow is exaggerated, but I think you can get the idea.

This can get you functioning and may wear in to the point that it works well...but don't plan on using it indefinately...get those new parts.

Yep, Polishing the sear wasn't a good Idea. Polishing the back bolt being careful not to round the notch would have been better.

eldiablo_si wrote: No everything is together properly and the bolt is in great condition.  I did however, polish the sear, so it took a layer or two of metal off.  But, like I said, it does work well on occassion.  It fires full auto and decocks.

That little polish job you put on the sear is probably the problem. An ever so slight rounding of the sharp corner of the sear that engages the notch will prevent it from engaging properly. Been there, done that also. It really requires a holder to maintain angles and uniformity from edge to edge when "polishing" a sear. Buy another sear and lube the rear bolts "O" ring and she'll be back in service.

Or you can work on the sear with a proper stone and you may re-establish the angle and sharpness to restore function, but it takes some very careful effort to re-establish those correct angles.

If you have touched the notch area of the rear bolt with the polishing bob that may have added to the failure mode. The rear bolt is relatively soft and easier to re-create the good sharp notch. But, that also takes careful work to get precisely square so that the sear engages dead on perfectly over the sear's width.