Handguard to receiver rail height differences and BUIS's

[AngelDeVille]

So on my "varnimter" ar15 I have an unknown brand of receiver, and works great, but it's .025" taller than my handguard at the rail.

The receiver is an overbuilt (fatter) with no FA and dust cover. (Does anyone know who made it?)

The handguard is a UTG pro 15.5"

I have fitted it with a Magpul front and Matech rear BUIS and I have no concerns with sighting.

I would prefer to use 45 degree A2 sights, but I'm concerned the rail height difference would seriously impact long range adjustments with that set-up.

I could run the 45's on the handquard without too much difficulty.

Can anybody think of some fixes?

[98Z5V]

0.025' isn't a big difference when on the same plane.  With 45* offsets, you're into two different axis that you have to comp/adjust for.  There's enough elevation adjustment to make it work on the same plane, so there will be enough elevation adjustment to work with the 45* setup.  You should have enough windage adjustment in the rear sight to make the 45* setup work on your rifle.

 

Ultimately, the best fix is a rail system that matches the upper receiver height.

[Robocop1051]

.025? That's smaller than 1/32" (it's actually 1/40", or 0.635mm, if that's even a real measurement)... did you mean .25 (1/4") or .125 (1/8")? Those would be significantly larger differences.

If it's truly a .025" difference, I doubt nearly a half millimeter will affect much, even with 45° sights, under 100 yards.

[AngelDeVille]

0.025' isn't a big difference when on the same plane.  With 45* offsets, you're into two different axis that you have to comp/adjust for.  There's enough elevation adjustment to make it work on the same plane, so there will be enough elevation adjustment to work with the 45* setup.  You should have enough windage adjustment in the rear sight to make the 45* setup work on your rifle.

 

Ultimately, the best fix is a rail system that matches the upper receiver height.

 

The handguard was level with a standard M4 upper so the problem child is the bastard upper I'm using.

I could change the upper, but I kinda like it.

 

.025? That's smaller than 1/32" (it's actually 1/40" if that's even a real measurement)... did you mean .25 (1/4") or .125 (1/8")? Those would be significantly larger differences.

Here's the pic of my set up and micrometer.

So if I had her sighted in with the large aperture at 100 meters then flipped to the long range, then adjusted the elevation wheel to 400-800 meters, where would I have impact issues?

[98Z5V]

 So if I had her sighted in with the large aperture at 100 meters then flipped to the long range, then adjusted the elevation wheel to 400-800 meters, where would I have impact issues?

 

That kinda doesn't matter - you're not shooting 800 meters with iron sights unless you're a competition guy.  If you're a competition guy, you won't be doing it with that rifle, and making successful competition scores. 

 

me thinks you needs de Space Gun setup.  That's my final answer, Regis.

[AngelDeVille]

That kinda doesn't matter - you're not shooting 800 meters with iron sights unless you're a competition guy.  If you're a competition guy, you won't be doing it with that rifle, and making successful competition scores. 

 

me thinks you needs de Space Gun setup.  That's my final answer, Regis.

Does the space gun set up require the use of duct tape? I'm in!

I think I'll try sighting it in with the offsets, and see if it holds zero between the 100-200 aperture and then flipping to the LR at 300.

If it does that well I'll consider it a success.

Even though I have Warne QD rings on both my scoped rifles I really don't want to remove the scope, then flip up the back up sights in order to engage a close range target. Call me lazy....

[shibiwan]

That upper looks like it was made out of a DPMS extrusion....

[AngelDeVille]

That upper looks like it was made out of a DPMS extrusion....

It's ugly as sin too, the handguard had "ears" that fit over the sides of a regular upper, and I had to remove them to fit this upper.

I can't see any marks or symbols anywhere, I even looked on the inside under the charging handle.

Edited March 29, 2015 by AngelDeVille

[98Z5V]

That upper is the DPMS slickside upper.  I have the same one on my 9mm.

[AngelDeVille]

Thanks, now I know who made it!

It's like a pretty fat girl.