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Posted: 10/5/2012 5:58:22 PM EDT
I like my aimpoint pretty far up, slightly off the front of the receiver. I've had enough people comment that it should be mounted directly on the receiver for accuracy. I understand the logic but my argument has always been that I can pick up the dot quicker and my front sight is mounted on the same rail. Am I just being hard-headed or does it really matter that much? BTW I'm using a 9" Samson Evolution.
Link Posted: 10/5/2012 6:49:55 PM EDT
If your Aim Point has no magnification, then you dont need to worry about accuracy.  Your not going for groups at 600 yards+.  Where it works best for you, is where it works best.
 
Link Posted: 10/5/2012 7:10:24 PM EDT
It's not accuracy, its POI shift, ie: a changing zero. If there's pressure on the handguard it will shift the POI. You're basically doing the exact opposite of a freefloat bbl. Instead of handguard pressure affecting POI due to moving the bbl without moving the optic, you're affecting the POI by moving the optic without moving the bbl.

In Green Eyes and Black Rifles Kyle Lamb states that depending on the amount of pressure applied one can move the POI 4" at 100 yards with a non free floated barrel. This is not an insignificant amount, especially at 200 and 300 meters, which is entirely within the practical capabilities of a RDS. This POI shift should also occur with a freefloating bbl and a handguard mounted optic. You might not be grouping, but shifting 8-12" off point of aim can put you seriously off a human size target.

That said, the closer to the receiver, theoretically less shift should occur.

What aimpoint are you using? If it's a standard PRO/M2/M3 tube style there are several manufactuers that make cantilevered mounts. If you have an M4, GG&G make one. There aren't any I'm aware of for the Micro series.
Link Posted: 10/5/2012 7:38:22 PM EDT
Quoted:
It's not accuracy, its POI shift, ie: a changing zero. If there's pressure on the handguard it will shift the POI. You're basically doing the exact opposite of a freefloat bbl. Instead of handguard pressure affecting POI due to moving the bbl without moving the optic, you're affecting the POI by moving the optic without moving the bbl.

In Green Eyes and Black Rifles Kyle Lamb states that depending on the amount of pressure applied one can move the POI 4" at 100 yards with a non free floated barrel.This is not an insignificant amount, especially at 200 and 300 meters, which is entirely within the practical capabilities of a RDS. This POI shift should also occur with a freefloating bbl and a handguard mounted optic. You might not be grouping, but shifting 8-12" off point of aim can put you seriously off a human size target.

That said, the closer to the receiver, theoretically less shift should occur.

What aimpoint are you using? If it's a standard PRO/M2/M3 tube style there are several manufactuers that make cantilevered mounts. If you have an M4, GG&G make one. There aren't any I'm aware of for the Micro series.


Figure also that most handguards flex easier than a barrel. Also when you flex the barrel the front sight moves with it minimizing the affect. If you're flexing the less rigid HG and the barrel doesn't move you could be magnifying the issue. Then again, most AR shooters are never going to crank on their slings like Kyle Lamb.
Link Posted: 10/5/2012 7:48:33 PM EDT
Quoted:
It's not accuracy, its POI shift, ie: a changing zero. If there's pressure on the handguard it will shift the POI. You're basically doing the exact opposite of a freefloat bbl. Instead of handguard pressure affecting POI due to moving the bbl without moving the optic, you're affecting the POI by moving the optic without moving the bbl.

In Green Eyes and Black Rifles Kyle Lamb states that depending on the amount of pressure applied one can move the POI 4" at 100 yards with a non free floated barrel. This is not an insignificant amount, especially at 200 and 300 meters, which is entirely within the practical capabilities of a RDS. This POI shift should also occur with a freefloating bbl and a handguard mounted optic. You might not be grouping, but shifting 8-12" off point of aim can put you seriously off a human size target.

That said, the closer to the receiver, theoretically less shift should occur.

What aimpoint are you using? If it's a standard PRO/M2/M3 tube style there are several manufactuers that make cantilevered mounts. If you have an M4, GG&G make one. There aren't any I'm aware of for the Micro series.


Thanks, this make perfect sense. I'm using a Aimpoint pro and I do plan on adding a x3 tube. I've looked at the LaRue mounts and it looks like it will do the trick.


Link Posted: 10/6/2012 10:24:51 AM EDT
Link Posted: 10/6/2012 12:10:47 PM EDT
Quoted:

Quoted:
If your Aim Point has no magnification, then you dont need to worry about accuracy.  Your not going for groups at 600 yards+.  Where it works best for you, is where it works best.  

Fail.

The best place to put the optic is on the upper, not on the hand guard, and don't bridge the two.
 


I was bridging the two I've moved it back and it's all good. Thanks for the feedback.
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