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View Full Version : M 305 shorty front sight.



graz
09-01-2015, 01:47 PM
Good day to all; I hope I am in the right place.

I have two Norcs that I had shortened by Dlask to 18.5 inch barrels; this is before the shorties were available over the counter. With the shorter barrels I see I have to have the rear aperature higher; 13 or 14 clicks from bottom, as opposed to the official nominal 8 clicks. The rear sight aperature just seems a little too high, and the rear sight protrudes somewhat above the rear sight ears. I don't get a cheekweld on the original norc mystery wood stock.

The easiest way to correct this is to file down the front sight a bit, but I am always hesitant to remove metal.

So anyone here with a factory 18.5" barrel; can you tell me how tall your front sight post is, how many clicks from bottom on the rear sight aperature, and maybe how high the center of the aperture is from the rear sight base, when you are zero'd at maybe 100 or 200 meters???

I might be making more of this than I need to, but curious.

Any help is appreciated.

Pics showing the GLFS; not sure if the factory 18.5's are exactly the same.

http://i146.photobucket.com/albums/r246/ipscgraz/P9011458_zpsde0gndip.jpg

http://i146.photobucket.com/albums/r246/ipscgraz/P9011457_zps7ntpcsk4.jpg

Haywire1
09-01-2015, 04:28 PM
He gaslock front sight your using is totally different than factory norc shorties. The 18.5" shorties use the same flashhider front sight as a 22" barrel. They do not use the glfs. The only shorty to use glfs is the dominion arms with the reversible muzzle brake that have more or less disappeared. A few places like blackrose, etc offer front sights that are shorty specific. Very generally shortening a barrel and using the factory sights will result in a poi lower than before the shortening. Meaning you need a shorter front sight to raise up the POI to match POA. Which your currently doing by adjusting your rear sight higher rather than shortening your front sight.

I would suggest filing down your front sight a little at a time u til your rear sight is centered, and your POI and POA match. Then measure the front sight and go shopping.

Side note, a glfs will need an even shorter post than a norc shorty would.

graz
09-01-2015, 06:52 PM
Thanks for that.

I google'd Blackrose and got a "Forbidden. You don't have permission to access this server" flag.

I guess someone told them I was coming.

At any rate, thanks for the reply.

Out comes the file...

Haywire1
09-01-2015, 07:01 PM
Just make sure your doing at the range lol
http://www.brownells.com/GunTech/Sight_Height_Calculator/detail.htm?lid=13186

graz
09-01-2015, 08:14 PM
The Brownell's formula won't work on an M14/M1/M1A style of rifle. That is based on a barrel mounted rear sight, not a receiver mounted sight. Good idea, though, and thank you for that.

Haywire1
09-01-2015, 09:11 PM
All you have to do is calculate your hieght over bore and they work fine. I have used them. Its the hieght over bore that matters for the math, not the location of the sight. I have also used the file method as well. Either way, good luck.