Ar 10 Wont Fire Semi Auto?

gobm667 · November 9, 2008, 08:34 PM

hey let me explain, i got a brand new ar 10 and figured i had to have a quad rail on it.. so my dumbass put it on there.. but when i did i moved the gas block.. then spent 40 rounds trying to adjust it so it would fire semi auto.. so i took it to a gun smith.. he adjusted it and said thats where it needed to be.. but he didnt test it.. its better but its still wont chamber the next round. it will eject the spent brass but it dont push the buffer spring back enuff to push another round in.. it will fire fine after i use the charging handle and put another round in there... so basicly i have a 1300$ single shot right now and im at wits end trying to figure this all out.. could it be that my ammo dont have enuff ass to push another round in there?? im using military surplus ammo? do i need to buy something with more ass? if so what? help me please???? i understand this is my fault and i would be very humbled for someone to help..
matt

PDXGS · November 9, 2008, 09:26 PM

Sell it to me...I'll take that lemon off your hands!

Some questions-
Have you tried different mags?
Has each mag you've tried been fully loaded?
What ammo are you using?
Have you check the rest of the gas system?

A statement-
Your smithy sounds like a rube

gobm667 · November 9, 2008, 09:28 PM

havent tryed a diffrent mag just the 20rd one that comes with it havent tried the 10 rd er.. and no they havent been fully loaded just a few rds in there each time.. the ammo i got a gun show i dont know the brand its surplus ammo came in a brown sealed back with like 160 rds in there.. the gas tube is clear..

DnPRK · November 9, 2008, 10:27 PM

There is a shoulder on the barrel aft of the gas block. If you push the gas block back against that shoulder, it will cut off the gas flow. Make sure there is a gap between the rear of the gas block and the shoulder. The gap should be about the thickness of a dime (thickness of the forward handguard cap).

I always mark the barrel and the gas block before installation. Then install the gas tube into the gas block. Then slide the gas block onto the barrel, line up the marks and tighten the allen screws.

gobm667 · November 10, 2008, 01:23 PM

anyone else have any suggestions??? looking for anything

10-96 · November 10, 2008, 11:39 PM

Measure from the back of the hole in the gas block to the back edge of the gas block with a micrometer. Transfer that measurement to the bbl and mark it. Now line up your block with your mark. Now what I did was to make a couple of wraps of electrical tape on a fired case and GENTLY put it part ways into the chamber. Now, blow into the bbl and place your finger in the receiver and over the gas tube to feel if any air comes out. What would work better would be to have an air compressor, that way you could free up a hand or two to adjust the block to feel for more air if a movement needs to be made. If I'm not mistaken, the distance from the shoulder on the bbl to the face of the block should be 7/32- but my mic won't read fractions and I've lost my cheat sheet, so I used the marks.

DnPRK · November 12, 2008, 10:50 PM

When you retract the charging handle until it stops. How far beyond the bolt catch does it go? It should be 1/4 to 3/8 inch behind the bolt catch.

PDXGS · November 13, 2008, 12:51 PM

I'm still pushing the magazine for the fault.....most of my AR variant issues have come down to bad mags or ammo...and rarely the rifle.

November 9, 2008, 08:34 PM	#1
gobm667 Senior Member Join Date: October 30, 2008 Location: chillicothe ohio Posts: 116	Ar 10 Wont Fire Semi Auto? hey let me explain, i got a brand new ar 10 and figured i had to have a quad rail on it.. so my dumbass put it on there.. but when i did i moved the gas block.. then spent 40 rounds trying to adjust it so it would fire semi auto.. so i took it to a gun smith.. he adjusted it and said thats where it needed to be.. but he didnt test it.. its better but its still wont chamber the next round. it will eject the spent brass but it dont push the buffer spring back enuff to push another round in.. it will fire fine after i use the charging handle and put another round in there... so basicly i have a 1300$ single shot right now and im at wits end trying to figure this all out.. could it be that my ammo dont have enuff ass to push another round in there?? im using military surplus ammo? do i need to buy something with more ass? if so what? help me please???? i understand this is my fault and i would be very humbled for someone to help.. matt

November 9, 2008, 09:26 PM	#2
PDXGS Senior Member Join Date: April 18, 2008 Location: Aloha, Oregon, USA, Earth Posts: 204	Sell it to me...I'll take that lemon off your hands! Some questions- Have you tried different mags? Has each mag you've tried been fully loaded? What ammo are you using? Have you check the rest of the gas system? A statement- Your smithy sounds like a rube __________________ "He who makes a beast of himself gets rid of the pain of being a man"-HST-Rest in Peace

November 10, 2008, 01:23 PM	#5
gobm667 Senior Member Join Date: October 30, 2008 Location: chillicothe ohio Posts: 116	thanks so much anyone else have any suggestions??? looking for anything

November 10, 2008, 11:39 PM	#6
10-96 Senior Member Join Date: October 19, 2005 Location: Tx Panhandle Territory Posts: 4,160	Measure from the back of the hole in the gas block to the back edge of the gas block with a micrometer. Transfer that measurement to the bbl and mark it. Now line up your block with your mark. Now what I did was to make a couple of wraps of electrical tape on a fired case and GENTLY put it part ways into the chamber. Now, blow into the bbl and place your finger in the receiver and over the gas tube to feel if any air comes out. What would work better would be to have an air compressor, that way you could free up a hand or two to adjust the block to feel for more air if a movement needs to be made. If I'm not mistaken, the distance from the shoulder on the bbl to the face of the block should be 7/32- but my mic won't read fractions and I've lost my cheat sheet, so I used the marks. __________________ Rednecks... Keeping the woods critter-free since March 2, 1836. (TX Independence Day) I suspect a thing or two... because I've seen a thing or two.

November 13, 2008, 12:51 PM	#8
PDXGS Senior Member Join Date: April 18, 2008 Location: Aloha, Oregon, USA, Earth Posts: 204	I'm still pushing the magazine for the fault.....most of my AR variant issues have come down to bad mags or ammo...and rarely the rifle. __________________ "He who makes a beast of himself gets rid of the pain of being a man"-HST-Rest in Peace

November 9, 2008, 09:28 PM	#3
gobm667 Senior Member Join Date: October 30, 2008 Location: chillicothe ohio Posts: 116	havent tryed a diffrent mag just the 20rd one that comes with it havent tried the 10 rd er.. and no they havent been fully loaded just a few rds in there each time.. the ammo i got a gun show i dont know the brand its surplus ammo came in a brown sealed back with like 160 rds in there.. the gas tube is clear..

November 9, 2008, 10:27 PM	#4
DnPRK Senior Member Join Date: August 24, 2001 Location: LC, Ca Posts: 1,917	There is a shoulder on the barrel aft of the gas block. If you push the gas block back against that shoulder, it will cut off the gas flow. Make sure there is a gap between the rear of the gas block and the shoulder. The gap should be about the thickness of a dime (thickness of the forward handguard cap). I always mark the barrel and the gas block before installation. Then install the gas tube into the gas block. Then slide the gas block onto the barrel, line up the marks and tighten the allen screws.

November 12, 2008, 10:50 PM	#7
DnPRK Senior Member Join Date: August 24, 2001 Location: LC, Ca Posts: 1,917	When you retract the charging handle until it stops. How far beyond the bolt catch does it go? It should be 1/4 to 3/8 inch behind the bolt catch.