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Sig 556 Swat & Magpul Trigger Guard Installation Problem

17847 Views 28 Replies 21 Participants Last post by  Xaque
I have a Sig 556 Swat and I am trying to install a Magpul enhanced trigger guard. The problem is the rear of the trigger guard fits fine and the roll pin goes in no problem. The problem is that the front of the trigger guard where the set screw goes in is not right. Rather, the set screw supplied by Magpul screws into the trigger guard fine but is barely too big in diameter for the receiver portion of the Sig. Any thoughts or suggestions? I called Magpul and they say it is a standard AR 1/8" set screw so they are unable to help. Figured I would turn to you folks as I have seen several 556's on the forums that have this trigger guard installed. Thanks in advance for the help.
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I had to use a drill bit slightly larger to ream the hole out to allow the
Magpul screw to fit. Worked fine.

I thought about that but it just scared the heck out of me having to drill into aluminum and there is so little room for error since there is not much material there.
Hey man I had the same problem with my install. I was about to drill but instead used alot of force to turn the screw in with a simple allen key and my hands. Had to push damn hard. Took a little of effort but it got in. Not sure if I can get it out though :lol:
Thought about trying that too but like you said, it's the getting it out part. Also that allen wrench is so tiny and thin I thought it might snap.
No because the original pin is spring loaded and attached to the original trigger guard.
Using a drill is quite safe and simple... Use a bit just large enough that it won't go through the hole...Takes longer to explain than do the job. Using too much pressure; or pounding can produce this result: ... gger+guard

I just did mine this weekend. My Magpul was slightly long, I had to carefuly file some material from the rear of the trigger guard where it hits the grip as it was pushing the guard past the roll pin hole. Also I had to drill out the hole in the front as others mentioned to get the screw in however my front hole in the trigger guard (the threaded one) was a little to far forward. so rather than drilling the hole out even BIGGER I chose to use a needle file and slightly oval the hole in the frame to allow the set screw to go in unencumbered.
Looks great, as a previous gunsmith and small arms dealer I have built up lots of AR's over the last 30 years (I am 50 now) and I really like the SIG 556.
Here is mine as I am just starting, pre magpul guard:

I plan on it being a better SIG version of this:
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I put the set screw on the allen wrench and ran it on my table top 1" belt sander to reduce the major diameter of the set screw. It reduced the od enough to work.
I figured that the set screw could be replaced a heck of a lot easier than the lower receiver.

why doesn't it supprise you it doesn't fit? Does your Chevy take BMW parts? It was made for an AR15/M16 lower.

Granted this would be a simple modifacation, but you'll going to have to make some careful mods.

Taking out a bad tooth seems simple too.... But you go to a dentist for that type of work.

If you want it done go to a gunsmith, someone with the machines, tools and skills to do it right.

I'll gladly pay someone to do the job right rather then take a dremel tool to a $1000 rifle.

Support your local gunsmith. It's always cheaper to have a gunsmith do it right the first time then to repair the damage you did from what you though you could do in your garage.

Not trying to be a ass, but just hate to see people f-up a nice gun thinking they are a gunsmith.
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I guess the reason it surprises me it doesn't fit is because I called Magpul directly and talked to their technical support people before I ordered this part, to ask if it would fit without any modifications and their answer was "yes". Oh well live and learn. Anyhow I took a combination of the ideas provided here and got it to fit. I took a fine round file to the hole to make sure there were no burrs inside. I virtually removed no metal other than a small amount of dust. Then I took another fine file to the threads of the set screw to remove sharp edges. I put a little gun oil on the threads and it popped right in with a little push.
If there's not a lot of difference, you might consider using a machine screw tap to "clean up" the hole to a slightly larger size.
happy to hear you did it! Congrats and enjoy man!
I like the sound of the light file method. DeBurring works often on small / fine parts.

Having said that....I'm OFF to do it myself....I ain't Skeird
Redbull72 said:
Done. EZ.
Good Deal!!!

I think mine was the exception to the rule with needing so much work.... I'll bet if I tried to stick my guard in an AR it would be the same issues..... I have put several in AR's with never a problem... mine was prob just out of spec.
Just got done installing mine and it was not plug-and-play.

First off the rear pin was damn tight. Make sure you are supporting your handguaurd, I really had to tap on it pretty hard to break it loose.

Once out, the front threaded pin was about 0.003" too large for the reciever hole. After about 3 drilling (each one progressively larger), I finally got it the right size. Be extra careful here, you really should use calipers if you're going to drill, it's easy to mess up and there is no undo.

Finally, I lightly sanded, and hit where I drilled with some black aluminum touch-up paint to get rid of burs and get it looking factory again.

All in all, about a solid 2 hours; I'm sure it could have took less but I was being very paranoid and overly cautious. Will post pics later.
i thought about getting an rra winter trigger gaurd. then realized it was ass ugly.

so i drilled the ear and put the magpul in.
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