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SIG 556 front sight roll pin trouble Login/Join 
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Hello all,

First, I am happy to be back here after a long hiatus due to marriage, kids, divorce and recovery. :-)

I have finally taken the tags off my SIG 556 SCM from 2008 and am now tinkering with it. I had a gunsmith install the SIG diopter sight set on it recently, but the front sight was slightly off (the notches on the base and sight weren't aligned), so I pushed out the roll pin and readjusted it. (Yeah, I later learned I didn't have to / shouldn't have done that.) Anyway, I tried getting the roll pin back into it, using a proper roll pin punch, but that didn't work. I then tried a new roll pin from a second diopter set I had, and still couldn't get the pin back in. Ugh...

So, now I'm looking for new roll pins - does anyone know the size, and for guidance on how to install a roll pin correctly. I always had trouble with roll pins on my classic pistols. Again, ugh. What non-banging tool could work on the front sight? I think the Little Crow Gunworks pusher is too large. The size of the E-Z RED pusher in unclear.

Thank you,
Ian
 
Posts: 499 | Location: MA | Registered: March 08, 2003Reply With QuoteReport This Post
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No sight pusher is needed. The dovetail isn't that tight so a brass or delrin punch should be all you need. Heck...a wood dowel will be good to get it generally in place.

MFI sells replacement rollpins for the front sight. I think I have several spares...I can check and drop one in the mail if you need it. Sig, TGS, MGW, etc...none have anything but MFI does.

Basic procedure I've found to work is to spin the right side of the adjuster onto the left once the sight is in place and align the holes. Use a punch to keep them aligned, then a starter punch to the new roll pin started (using the punch as a slave pin of sorts). A flat punch is best as a domed style while easier to keep on there, can flare the end open (ask me how I know why).

The trouble occurs when you try to force the pin through the hole in the shaft of the left adjuster. If its not lined up, no amount of pounding on it will work but it will ruin your pin (see above). So...if its not tapping in easily, tap it out from the opposite side and try again after ensuring its lined up properly.

You're basically having to tap a roll pin through three holes, not one.

Let me know if you need a hand....done this too many times already so I know the pain.
 
Posts: 926 | Location: Leesburg VA | Registered: December 21, 2014Reply With QuoteReport This Post
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Hello PGT,

Thank you for your reply. I ordered some pins and screws from MFI. There was an issue with shipping and the owner called me right away to clear it up. Wow!!!

Yeah, I got the flared pins too with the roll pin punch. Ugh. I should've taped around the sight too to prevent nicks. Ugh.

I think I'll use a larger diameter punch to keep all the holes perfectly aligned for when putting the pin in.

Ian


"Once is happenstance, twice is coincidence, three times is enemy action." - Ian Fleming
 
Posts: 499 | Location: MA | Registered: March 08, 2003Reply With QuoteReport This Post
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Picture of Greymann
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Try grinding a taper on the roll pin to get it started,then wooden dowel to drive it home.
 
Posts: 14 | Location: way out west | Registered: March 21, 2017Reply With QuoteReport This Post
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