Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Posted: 9/29/2004 11:04:12 AM EST
[Last Edit: 9/29/2004 11:09:29 AM EST by dadman]
I looked at FAQ II and saw something similiar about front sight post height, but have further questions.

Recently assembled an AR15 and took it to the range for ops check and testing. Distance was 50 yds.

The rifle has a Cavalry Arms lower, flat-top upper from JT Distributing, and Bushmaster 20" barrel assy with std. FSB.
Rear sight is an Armalite detachable carry handle. I was told by the person I bought it from at this board that the sight/handle is a NM version. The two aperatures seem to be the same diameter.

The problems I'm having with the rifle are:

1. Before zero, the detach handle/rear sight was at one click above 6/3.
I adjusted per the Santos/IBSZ instructions before shooting. It is now set at -4 clicks below 6/3.
When shooting, it was impacting high and left. Just outside a 5.5" Shoot and See target.
Got it to POA/POI at 50 yds using non-bench positions.

The rear sight/windage is almost one mark to the right of center.
The front sight post was raised/turned out towards the lower impact direction.
The shoulder of the front post is slightly above the FSB hole/upper surface, but still secure. Excuse the technical term, but it's a hair above.

Is either one of these after zero adjustments acceptable?
Should the front sight post shoulder be flush or below the hole/recess of the FSB that it screws into?

2. After doing the IBSZ rear sight adjustment, the elevation wheel/drum halves are a little loose. The sight itself seems tight, just the wheel halves are slightly loose in relation to each other.
The 1/16 allen screw has been double checked for tightness.
Is there something within the wheel that's supposed to make it tighter?


Link Posted: 9/29/2004 3:08:34 PM EST
[Last Edit: 9/29/2004 3:09:04 PM EST by gregw45]

Originally Posted By dadman:
Is either one of these after zero adjustments acceptable?
Should the front sight post shoulder be flush or below the hole/recess of the FSB that it screws into?



Sounds pretty good. Very close to mechanical zero.



2. After doing the IBSZ rear sight adjustment, the elevation wheel/drum halves are a little loose. The sight itself seems tight, just the wheel halves are slightly loose in relation to each other.


Had the same thing happen with a Bushy A2 upper. I didn't care one way or the other, but eventually ended up taking the 1/16 allen wrench and loosened, then tightened her down + a little extra. It worked and if it hadn't I suppose I would have tried a little loc-tite.

Link Posted: 9/29/2004 3:28:10 PM EST
Link Posted: 9/29/2004 4:37:47 PM EST
gregw45 and Tweak,
Thanks for the replies. Helps to know others have experienced similiar and shot on.

When looking under the front post through the hole under the FSB, the post still seems threaded into the base.
The spring loaded detent pin for the front post seems to be locking/engaging like it should.
The front post also makes contact with the sides of the base hole.
Would like it to have more contact though.

The upper half of the drum/wheel seems to be the culprit with the looseness.
Running through different elevation settings, the lower wheel seems firm, and the upper wheel is loose on the lower. Appears as if the contact surfaces and clearances where the upper and lower meet are a bit on the big side.
A knowledgeable AR shooter at the range said he's seen other AR's with different degrees of elevation wheel feel. Some tight, some too tight, some free, and mine the loosest of his experience.

Rifle shoots good. Am pleased with how it turned out.
Will try 100 & 200 yds this weekend.
Coyote Brown and Krylon Khaki look good. I need a matching puirse to go with it.
Link Posted: 9/29/2004 9:36:06 PM EST
[Last Edit: 9/29/2004 9:41:55 PM EST by Tweak]
Link Posted: 9/30/2004 2:24:17 AM EST

Originally Posted By Tweak:
Did you try Greg's suggestion of loosening the set screw and slightly wiggling the elevation index?


Sort of.
When doing the IBSZ, the 1/16 screw was loosened 3 turns, then tightened.
Afterwards, the screw was loosened then tightened after noticing the wheel-half slop.
Didn't try wiggling the elevation index.

Could you clarify what you mean by raising the rear sight base, or how?
Link Posted: 10/3/2004 1:18:44 AM EST
Top Top