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IP and S'G' Trigger Notches and Steps

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sling00 View Drop Down
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    Posted: May 15 2017 at 2:43pm
I noticed the S’G’ trigger on my CMP-IBM mixmaster extraordinaire has a more defined notch and other machine cuts than the one on my S’G’.  I found in CCNL #21 a brief discussion of three different shapes.  This trigger appears to have more cuts than number 1 in the NL as well as the one pictured in the Parts page.   In addition to the step down it has a step up near the end of the trigger.     

NL #130, page 10 has an IP trigger drawing provided by Mr. Ruth.  Although NL 250 says this drawing is for the notch and step, it appears to be more for the trigger arm than the pull.  Can someone read it better?  Note that the printed drawing is Sheet No 1 of 2 sheets.  Any chance someone has Sheet number 2?     

So with all that said, has anyone noticed similar cuts on an IP or S’G’ trigger?  Perhaps this is just the machining being off a little or is this a remnant of the tooling?  I’ve attempted a couple pictures of my trigger and in particular the cuts on the bottom half of the trigger to try and help show what I’m lacking in my description.     



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Dan Pinto, Photo Editor

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Post Options Post Options   Thanks (0) Thanks(0)   Quote New2brass Quote  Post ReplyReply Direct Link To This Post Posted: May 15 2017 at 2:59pm
notice how the notch is slightly tapered. Pedersen was a old school gunmaker.
 
His method for lining up a part from one machine to another was jigs with locator pins that would go in the holes in a billet or forging. from there the part would get machined then moved to another for more machining. The problem with this method is it can cause compounded errors from machine to machine due to them not lining up correctly. I believe this is what led to the loss of contract with IP.
 
As they say you cannot teach an old dog new tricks.
 
Early on you see the holes closer to the finished part. they then worked their way further out. so when final machining was done it would almost eliminate the holes.
 
When SG took over they used the machinery on hand. I do not know if they used the holes for locating and may very well be left over from the forgings. They may have used the pin setups for non critical steps.
 
So yes you will see remnants on triggers S'G' marked.
 You may want to look up the interview with Doffner for more info
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