I would like to remove the front a sight and replace the gas block as well to accommodate and front flip up sight but i cant find a DIY on the steps for removal... Does anyone have them or a vid?

http://www.ar15.com/forums/t_3_4/226..****ctions_.html

Scroll down this page.

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-John

I just put a YHM flip up sight/gas block on my Sport a few weeks ago. The taper pins are put in very tight. Support the barrel with wood blocks or you can buy a front sight block to hold it. I used wood blocks. AR-15 FRONT SIGHT BENCH BLOCK - Brownells The pins come out from right side to the left side. I had to buy a set of steel punches to get the pins out. My brass punches bent to much. It will take a few good whacks with a hammer to break them loose and then they will fall out.

The gas tube has a small roll pin that also has to come out. It will take a 1/16 in punch to get it out. On my Sport the gas tube pin hole on the right side had to be enlarged slightly to pass the 1/16 in punch. I used a 3/8 drill bit by hand to enlarge the hole. A couple of raps with the hammer and it will come out ok. Save the pin, you'll need it when you put the new sight/gas block on.

You'll need to take the flash suppressor off the front of the barrel to get the sight off. It took me about 1/2 hour to get everything off and the new flip up sight base back on.

3/18/12 Update: Correction - The FSB and Gas Tube pins come out from the right side to the left side. I had to go back and look at my FSB to make sure. Sorry for the confusion this may have caused.

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gunfighter48
NRA Life Member

Good explanation. I did the same for another gentleman on here literally yesterday. It is not as difficult as some would let on, but needs patient attention. I do however want to add to your abridged tutorial that the proper punch size for the gas tube pin is 5/64, gotten at any hardware store, and require no fitting to use. Other than that, same description I gave, and yours took less typing! DIY is the best way to learn about the inner workings.

Great DIY explanation of this process. I'll be saving this thread for future referrence

What is the barrel diameter on this gun? .75" ? Need to put on a gas block

Calipers? Always good to have around and measure yourself.

I leave that up to the girlfriend......... but to each his own!!!

SHE Has calipers????.

You need calipers when you're measuring something that small.

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*Aim small, miss small...

3/8's seams like a HUGE step up from 1/16th. Could you have meant to say 1/8th?

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M&P9/9C/Shieldx2/Sportx2/15-22

I think he meant 3/8 DRIVE (As opposed to 1/2), not the bit size.

The pins on the S&W are reversed from normal drive from right to left (when holding in shooting position) I learned this the hard way! I installed a Midwest Industries gas block and sight

I think he meant a 3/32"..... it's between 1/16 and 1/8.

I had my girlfriend check it with a caliper..... that's how big she said it was!!!!!!!!!!!!!!!!!!! (Efff my life, I walked right into that one.)

I did use a 3/8" drill bit as a counter sink to chamfer (widen) the hole on the left side of the sight. I held in in my fingers and twisted back and forth a few times.

When the FSB was cast the hole on the left side was slightly smaller than the roll pin diameter. So when I tried to use a 1/16" punch it wouldn't go thru the hole. When they drilled the hole for the roll pin the drill bit didn't go all the way thru the casting. Thus I had to enlarge the outside of the hole very slightly so the 1/16" punch would go thru the casting and drive out the gas tube roll pin. The reason for the large diameter drill bit was to widen the outside edge of the hole without damaging the roll pin. The larger the diameter of the drill bit the shallower the depth of the hole widening.

Hope this all makes sense. It's an old trick I learned from a high school shop teacher many decades ago. It's not unusual to find a hole on one side of a casting is smaller than the hole on the other side. Although it's certainly a lot less common today with CNC machining than it used to be.

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gunfighter48
NRA Life Member

Thanks gunfighter, make perfect sense now.

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M&P9/9C/Shieldx2/Sportx2/15-22

I'm a little confused, guys. Do you drive the pins on the GB/FS out from the right side or the left side? I'm about to put a new gas block on my M&P15 sport and I want to make sure that I'm driving the pins out the right way. Most AR's drive from the left side out, right? Thanks!

The M&P's are backwards

Thanks. I used a micrometer to measure both sides of the pin and finally figured it out.

I too have done this and would suggest putting your weapon on a very solid surface to work on. Although my work bench is pretty solid, it was absorbing some of the force of my hammer. Moved to the concrete garage floor....perfect.

Sorry for the confusion folks. I went back to my original post and corrected it. The pins DO come out from the right to the left side of the FSB and gas tube. I went back and looked at my FSB and found my mistake. Sorry for the confusion this has caused. Old feeble brain and dumb fingers doing the typing!!!

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gunfighter48
NRA Life Member