james m Posted May 28, 2013 Report Share Posted May 28, 2013 (edited) With all the discussion about how these receivers are machine ; I decided to try something I hadn't attempted in the past. This was to see it The Blish Lock slots machined into my 80% Philadelphia Ordnance receiver would accept the Blish lock. As I think you all can see this isn't going to happen. Frankly it isn't even close to entering the slots. If any of you are wondering this is a military surplus Blish lock and it fits perfectly with a military surplus bolt and actuator .I am having problems posting pictures here but I think you see my point. I purposefully reversed the lock so you can see it won't fit either way. Here is an assembled bolt using that exact Blish lock. Perhaps Bob can explain what the exact problem my be.Jim Edited May 28, 2013 by james m Link to comment Share on other sites More sharing options...
reconbob Posted May 28, 2013 Author Report Share Posted May 28, 2013 The H-lock or Blish lock cuts are correctly machined in the receiver. The lock does not drop inbecause the slots need to be filed/beveled, and because the bolt pocket is not finished machined,but slightly undersized. The pocket is approx 0.01" undersize in width and approx 0.020" undersizein depth. The idea here is that when the pocket is finished the finish cuts will machine away all surfacesleaving smooth surfaces. There is a tiny bump at the front that would be machined away if the pocket was finished - thetip of the scribe is pointing to it. This can be quickly dressed with a file if you want you lock to dropin: http://i51.photobucket.com/albums/f392/reconbob/IMG_3428_zpsfd90a82d.jpg Also the edges of the slots need to be beveled as shown in this photo. This can also be donewith a file and if you break the edges as shown the lock will drop in: http://i51.photobucket.com/albums/f392/reconbob/IMG_3429_zpsb0fe90c5.jpg The machining of the H-lock cuts was never intended to provide a finished bolt pocket, butto put the cuts in the right place so that if the receiver was finished later you would not have toworry about the H-lock cuts. The difficulty in machining the H-lock cuts is that you can't measurethem until after they are machined so its easy to go wrong. We are able to constantly check theposition of the slots - this is an operation that is 100% inspected - and we also routinely finish 80%receivers into 100% receivers which we test fire using the same tools and programs. So there is nothing "wrong" with your receiver. Bob Link to comment Share on other sites More sharing options...
james m Posted May 28, 2013 Report Share Posted May 28, 2013 (edited) Thanks for the additional information. Since this is a display only gun I don't intend to make any further modifications to the receiver at this time. Perhaps some day a degree of sensibility will return to this Countryand this receiver can be machined out the rest of the way to completion.Jim Edited May 28, 2013 by james m Link to comment Share on other sites More sharing options...
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