Almost done working on my upper while im still waiting for fid. After some dremel work and a lot of test fitting i finally got the vltor casv handguard to work with the adams arms piston system. im sure most of you are familiar with the casv, its a piggy back system that raises the upper receivers flat top (about .48 inches according to my digital calliper) Anyway, my magpul flip ups arrived this weekend, so my question is could i put the buis at the vltor's level (picture 3) or do they have to stay at the upper's flat top level (picture 1 and 2) the reason i want to raise them is for cowitness purposes. i can cowitness at the lower level with a low 30mm mount, but i also want to use a magnifier behind the optic, and the problem is i havent been able to find any low flip to side 30mm magnifier mounts

 

Everything should be on the same plane or it won't line up

Besides the fact that your front sight appears to be backwards, you are more than likely going to have all kinds of issues.

 

1-MBUS sights are designed to be mounted at the same height.

 

2- If not mounted at the same hight, you wil have a hard time getting a zero, because the front sight post will need to make up the .48" of elevation.

 

3- Magpul MBUS sights are not meant to be mounted on the gas block. The high heat and polymer do not play nicely with one another.

i understand they need to be at the same level maybe i wasnt clear in my original post. let me try again. the adams arms picatinny is the exact level of the upper's picatinny, and the vltor piggy back doesnt go all the way back to the charging handle, it allows enought room to mount a back up sight on the upper's flat top, so....the front and the rear would be on the same level, no problems. my question is, can i put both front and rear .48 inches higher on the stepped up portion of the vltor?

Besides the fact that your front sight appears to be backwards, you are more than likely going to have all kinds of issues.

 

1-MBUS sights are designed to be mounted at the same height.

 

2- If not mounted at the same hight, you wil have a hard time getting a zero, because the front sight post will need to make up the .48" of elevation.

 

3- Magpul MBUS sights are not meant to be mounted on the gas block. The high heat and polymer do not play nicely with one another.

 

This exactly. You need a gas block height front sight, preferably one that won't melt.

http://www.midwayusa.com/product/2344177563/midwest-industries-flip-up-front-sight-gas-block-height-ar-15-aluminum

Not all gas blocks are created equal. The AA Piston kit gasblock does not need an extended front sight like most railed gasblocks do. The rail on the GB is the same height as the flat top on the receiver.

 

While you can use a standard folding front sight, a Magpul BUIS is NOT a good choice. It has the potential to soften the plastic making you lose zero. Spend some dough on a decent metal sight and you will be much happier.

 

As far as mounting the BUIS on the VLTOR riser I do not recommend it. The extra height may make co-witnessing an optic difficult as well as making your cheekweld less comfortable and less consistent degrading accuracy.

 

Mount the rear sight to the flat top at the rear of the VLTOR rail and the front to the gasblock. This will keep everything standard and make zeroing and adjustments easier.

 

One consideration is when you decide on an optic make sure you purchase a mount that is the correct height for the VLTOR rail.

 

Good luck.

i understand they need to be at the same level maybe i wasnt clear in my original post. let me try again. the adams arms picatinny is the exact level of the upper's picatinny, and the vltor piggy back doesnt go all the way back to the charging handle, it allows enought room to mount a back up sight on the upper's flat top, so....the front and the rear would be on the same level, no problems. my question is, can i put both front and rear .48 inches higher on the stepped up portion of the vltor?

 

You can put them both on the riser, but I'm not sure how well the rear will work for you if you push it forward. Try it and see. They'll work on the same plane with a carbine length tube, or a 15" tube. You wil jsut have to re-zero if the rear peep doesn't become unusable for you form pushing it forward.

 

If it does, you need to get a metal front sight that won't melt that is designed for same plane applications. You can use that with the rear MBUS which is designed for same plane use, or you can replace both. If you put the rear sight on the flat top, but the fornt on the riser, you will not have enough sight travel to zero it on any front sight I have seen.

So your looking to go with an aimpoint or something, a separate magnifier, a rail on top of a rail, a piston system, & Everything needs to co witness? I'm lost in the sauce & I hope you have gorilla arms.

just throwing this out there... but with flat top receivers with the ability for a nice long full gun level rail.. why would you go with something like this? why did you not just choose a normal rail system that will give you the full unobstructed length of the rail..

I think he needed the extra height if the VLTOR rail to fit the AA piston under it.

I think he needed the extra height if the VLTOR rail to fit the AA piston under it.

 

gotcha.. I thought there were other options out there to accommodate stuff like that.

gotcha.. I thought there were other options out there to accommodate stuff like that.

 

There are, but the casv looks cool.

 

This is reason #246 why I don't want a piston upper.

just throwing this out there... but with flat top receivers with the ability for a nice long full gun level rail.. why would you go with something like this? why did you not just choose a normal rail system that will give you the full unobstructed length of the rail..

 

i just like the casv look, i didnt anticipate i was gonna run into a problem with cowitnessing. i ditched the magpul buis, got this burris ar536 5x red dot instead and gave up on trying to cowitness, i still love my casv rail regardless.