I have been an AR owner for 20 years and served in the Marine Corps for 21 years, so I have some familiarity with the AR15/M16. In October, I bought my first M4 and am having problems getting it to hold a zero.
My M4 is a flat top, stag lower, Daniel Defense light rails, PWS piston system with a DTI 1X9 heavy barrel. It actually weighs more than my full size Colt AR.
The problem is that it shoots extremely low. If I lower the front sight post all the way down, it will hit the bullseye at 25M. To be sure that there was nothing wrong with my sights, I changed them out from the carry handle site to a Matech rear with a Yankee Hill front.
Yesterday, I shot it with the new sights and it was still shooting low, about 4 inches at 30 feet. Funny thing is that it shoots a very tight group.
Any ideas on what could be the problem? Is it possible that there was some minor imperfection when it was assembled?
Thank you for any insight or recommendations (including taking it back to the gun shop).
I have been an AR owner for 20 years and served in the Marine Corps for 21 years, so I have some familiarity with the AR15/M16. In October, I bought my first M4 and am having problems getting it to hold a zero.
My M4 is a flat top, stag lower, Daniel Defense light rails, PWS piston system with a DTI 1X9 heavy barrel. It actually weighs more than my full size Colt AR.
The problem is that it shoots extremely low. If I lower the front sight post all the way down, it will hit the bullseye at 25M. To be sure that there was nothing wrong with my sights, I changed them out from the carry handle site to a Matech rear with a Yankee Hill front.
Yesterday, I shot it with the new sights and it was still shooting low, about 4 inches at 30 feet. Funny thing is that it shoots a very tight group.
Any ideas on what could be the problem? Is it possible that there was some minor imperfection when it was assembled?
Thank you for any insight or recommendations (including taking it back to the gun shop).
I would try the 50/200 yd zero as mentioned above. Shooting @ close ranges you have to contend with the sight/bore offset, 2.5" or so. Let us know how it goes.
Yeap,your trying to zero at too close of a range using the set mechanical limits of the sights.HOB at that range makes it difficult without modification to the A2 rear sight.
Ive never tried to sight in flipup BUIS in at that range so I cant help in that regard.
But if you want to zero at 25M,then I’d look at using the carry handle setup per the -10 for the old Marine Corp 25M battle sight zero.
HTH
Go with the 50/200 meter zero. It is a good compromise for all around shooting. I remember an anecdote from a trainer that mentioned a police agency who zeroed at 10m because that was “the average engagement distance” or some such BS. That pretty much screws you for shooting at any practical range. Remember that within 25m the shooter needs to begin compensating for the difference between the sights and the bore. At 15m, one would need to aim about 1.5" high and 2.6" high at 5m.
Had it not been for the carry handle design on the original Stoner design, the sights could have been mounted low to the bore and provided a much mre intuitive system.
No because then you’d need to drop your head too far to get a consistent cheek weld.
The reason the sights on a classic hunting rifle are close to the bore line is the stock is dropped to get into the pocket of your shoulder. Stoner wanted the bore line to go directly into the shoulder to decrease muzzle rise. With the bore line low enough to be in line with the shoulder the sights need to be taller. Also if the sights were lower we wouldn’t have the great benefit of being able to co-witness with optics…
It’s an ingenious solution really, and with a 50/200y zero your POI will be within 2.5in of POA out to approx 250y which is quite intuitive.
that is indeed very strange. I find it impossible to set the sights such that it will shoot 4 inches below even at 25yards.
you mentioned that you changed your front sight. there are 2 kinds of front sights that attaches to picatinny. 1 kind attaches to the picatinny rail. and another kind attaches to a picatinny gas block.
picatinny rail is usually the same level with your flat top
while the gasblock rail is usually lower.
you might have used a front sight for the gas block and attached it to your rail.
Agree to disagree. In regards to co-witness, the concept wasn’t even around when Stoner designed the rifle. But…time to stop hijacking the thread. Let’s focus on the original poster’s problem…
The stock being inline with the bore axis to control muzzle rise and the resulting sight height has been documented; look it up…
You are correct that the co-witness of sights and optics wasn’t concieved when the AR was designed, but the intelligent poster will realize I never said Mr Stoner raised the sights to co-witness optics I said “if the sights were lower we wouldn’t have the great benefit of being able to co-witness with optics…”
