HansTheHobbit
09-22-15, 16:10
Hi all, I'm relatively new to the forum. Just did a build using Vltor's VIS monolithic upper, and I thought I'd post it in case anyone was thinking about using one. So I'll give a brief report of how I came to build this, as per the guidelines of the forum. Skip to pics if you don't care, and I'll also leave a review of the VIS at the bottom. Here goes...
The concept of the build could be described as a "Recce" style. Funny thing is, I wasn't really aware of the Recce until afterwards; I actually thought that the Recce and Mk12 were the same thing, lol. Anyway, I came to the conclusion a while back that the one advantage the AR has over other platforms, such as the SCAR or AK, is that it has exceptional accuracy potential due to its DI system. So I decided that any future builds would be planned around accuracy as the primary concern. I wasn't out to build a sniper rifle, or even an SPR for that matter, just an exceptionally accurate carbine. My goal was a half MOA minimum gun that could do anything from close quarters out to ~500-600 yards.
I then did a bunch of research on ballistics with the 77 grain SMK, and decided that 16'' was the best bang for my buck. I didn't think an extra fifty yards of range was worth the additional weight and length of an 18 or 20 inch barrel. YMMV, of course. For me, though, going with a longer barrel was moving too far in the direction of a sniper rifle, which was not my intent. I didn't go any shorter because I concluded long ago that the mid length gas system was the shortest I was willing to go for reliability concerns. Any shorter, and you're ripping that brass out of the chamber before it wants to come out, which isn't good for a precision chamber I wouldn't imagine. Now I'm not getting down on SBRs; it's just not my thing, and there are better platforms to SBR than DI guns. Not trying to start an argument, just trying to explain my thought process. I probably would have done a 14.5'' middie, but didn't feel like the tax stamp was worth the expense or limitations and didn't want to pin the muzzle. I am even considering doing a future build with a precision 300BLK 8'' barrel. It would be pretty cool to make head shots at 400 yards with a suppressed 300BLK. :cool:
I then looked into ways to maximize accuracy. I wanted to do every little thing, within reason, to increase its accuracy potential. The biggest thing I came up with was a monolithic upper. It theoretically is more rigid, and therefore more accurate. Perhaps more importantly, and this isn't just theoretical, you can mount optics anywhere on that rail without any risk of vertical stringing. Knowing that optics were going to be a primary concern, it's good to know in advance that I can use any scope/mount combo on the market. I studied monolithic designs, and I think the most important thing about them is that they take all the stress off of the barrel flange, as the handguard is supported by the walls of the upper, not the barrel nut. So you get a truly free floating barrel, just as you would find with a bolt action rifle. You can aggressively load the bipod without any risk of stringing. I had it narrowed down to two options, the Vltor and LMT. The Vltor was half the price, and it came in keymod, so that was an easy choice. Looking at the two designs, I also think that the Vltor does a better job of isolating the barrel and removing it from the stresses induced by the handguard.
For the barrel, I just looked up reviews online, and the consensus pointed towards Wilson. So I got a Wilson 16'' stainless barrel and called it a day. In retrospect, I wish I had gone to a custom barrel shop, but time will tell if I made a good choice. I chose a 1:7 twist because I had zero interest in anything under 60 grains. I know what they say about 1:8 being good enough for SMKs, but they also say that 1:7 is just as good and possibly a little better. I also read some anecdotal evidence that SMKs lose some of their terminal performance from a 1:8 twist, i.e. that they open up and expand better with the higher rotational velocity. BTW, the relationship between rotational velocity and terminal performance is a good read if you care to research it. Very interesting subject, way above my pay grade, but fascinating nonetheless. I also got a Wilson nickel teflon BCG. I'm very happy with it, definitely a step above nickel boron.
As of right now, I have a JARD adjustable two stage trigger in it. I'm not sure if I will keep it that way. I'm thinking about moving to a 3.5 pound single stage, and I'm especially fond of the flat triggers from Geissele. If they ever come out with that 3 position trigger, then that will be a no brainer. At some point I will play with trying to reduce the lock time. I would like to try using a titanium firing pin, but I don't know if I will be happy with the reliability. We'll just have to see how it holds up or if it spears my primers.
I also haven't decided what I want to do for optics. I'm leaning towards the Leupold Mark 8 1.1-8x, but also considering the 1.1-6x. I want a scope that can realize the potential of the rifle and still work in close quarters. I'm also considering doing a variable 10x scope with an offset RMR sight. I will have to play with it, and see what its practical range is. Part of me thinks that the practical potential for good terminal performance is about 300 meters or less, which would demand less scope. Again, I'm not trying to build a sniper rifle, and I have no illusions about the 5.56 being a long range cartridge. I know it can accurately go out to 600ish, but I'm rather dubious as to its terminal performance at long ranges. I'll just have to do more reading before I go throwing money at a new scope. Unfortunately I won't be able to give a good range report and grouping until I decide what glass to put on it.
So without further adieu, here are the photos.
http://i1300.photobucket.com/albums/ag97/hansthehobbit/DSCN0187_zpsbbplhmdi.jpg
http://i1300.photobucket.com/albums/ag97/hansthehobbit/DSCN0205_zpsbkapq1bn.jpg
Here's where I modified a redi mag to clear the VIS.
http://i1300.photobucket.com/albums/ag97/hansthehobbit/c31de70c-ed1b-446d-bf14-2b9e579c8b32_zpsibtnhthl.jpg
Vltor VIS Review:
I have nothing but positive things to say about the VIS. It was a breeze to install, it handles very well, and it makes a great platform for mounting accessories. It also has an extremely tight flange, which makes for a rock solid setup. Certainly no need to bed the barrel extension with this baby. To make installation easier, put your barrel in the freezer, then take a hair dryer to the upper. And lube up the barrel extension.
The best thing about the VIS is that there's no indexing the barrel nut, as the gas tube goes over it. So you simply torque it to 50 ft/lbs and that's it. The one inconvenience was that Vltor specifies using a particular type of anti-seize, as opposed to the usual moly grease (like aeroshell 33), and it's rather difficult to find. I was able to get it from amazon. Definitely don't use moly grease, as it will change the torque spec, and make sure that your anti-seize is safe for aluminum if you deviate from their brand of choice. They said the 100% copper from Brownell's was also acceptable.
The other thing is that you must use a reaction rod to install the barrel nut. A BEV block might work, but the reaction rod is far better, as you must be able to turn the rifle upside down to properly access the barrel nut. It's a very tight working space.
Lastly, to undo the tabs to remove the bottom handguard, you will need to make a little tool out of a punch. Simply bend the punch at a right angle, then use it to tap the tabs out. Works like a charm. Vltor says you can use a bullet tip, but I found that to be patently not true, at least when it's new. Maybe it will loosen up over time, but right now you will need the aforementioned bent punch. Just clamp the punch in a vice where you want the bend, about a centimeter or so from the tip, and bend it on over.
The concept of the build could be described as a "Recce" style. Funny thing is, I wasn't really aware of the Recce until afterwards; I actually thought that the Recce and Mk12 were the same thing, lol. Anyway, I came to the conclusion a while back that the one advantage the AR has over other platforms, such as the SCAR or AK, is that it has exceptional accuracy potential due to its DI system. So I decided that any future builds would be planned around accuracy as the primary concern. I wasn't out to build a sniper rifle, or even an SPR for that matter, just an exceptionally accurate carbine. My goal was a half MOA minimum gun that could do anything from close quarters out to ~500-600 yards.
I then did a bunch of research on ballistics with the 77 grain SMK, and decided that 16'' was the best bang for my buck. I didn't think an extra fifty yards of range was worth the additional weight and length of an 18 or 20 inch barrel. YMMV, of course. For me, though, going with a longer barrel was moving too far in the direction of a sniper rifle, which was not my intent. I didn't go any shorter because I concluded long ago that the mid length gas system was the shortest I was willing to go for reliability concerns. Any shorter, and you're ripping that brass out of the chamber before it wants to come out, which isn't good for a precision chamber I wouldn't imagine. Now I'm not getting down on SBRs; it's just not my thing, and there are better platforms to SBR than DI guns. Not trying to start an argument, just trying to explain my thought process. I probably would have done a 14.5'' middie, but didn't feel like the tax stamp was worth the expense or limitations and didn't want to pin the muzzle. I am even considering doing a future build with a precision 300BLK 8'' barrel. It would be pretty cool to make head shots at 400 yards with a suppressed 300BLK. :cool:
I then looked into ways to maximize accuracy. I wanted to do every little thing, within reason, to increase its accuracy potential. The biggest thing I came up with was a monolithic upper. It theoretically is more rigid, and therefore more accurate. Perhaps more importantly, and this isn't just theoretical, you can mount optics anywhere on that rail without any risk of vertical stringing. Knowing that optics were going to be a primary concern, it's good to know in advance that I can use any scope/mount combo on the market. I studied monolithic designs, and I think the most important thing about them is that they take all the stress off of the barrel flange, as the handguard is supported by the walls of the upper, not the barrel nut. So you get a truly free floating barrel, just as you would find with a bolt action rifle. You can aggressively load the bipod without any risk of stringing. I had it narrowed down to two options, the Vltor and LMT. The Vltor was half the price, and it came in keymod, so that was an easy choice. Looking at the two designs, I also think that the Vltor does a better job of isolating the barrel and removing it from the stresses induced by the handguard.
For the barrel, I just looked up reviews online, and the consensus pointed towards Wilson. So I got a Wilson 16'' stainless barrel and called it a day. In retrospect, I wish I had gone to a custom barrel shop, but time will tell if I made a good choice. I chose a 1:7 twist because I had zero interest in anything under 60 grains. I know what they say about 1:8 being good enough for SMKs, but they also say that 1:7 is just as good and possibly a little better. I also read some anecdotal evidence that SMKs lose some of their terminal performance from a 1:8 twist, i.e. that they open up and expand better with the higher rotational velocity. BTW, the relationship between rotational velocity and terminal performance is a good read if you care to research it. Very interesting subject, way above my pay grade, but fascinating nonetheless. I also got a Wilson nickel teflon BCG. I'm very happy with it, definitely a step above nickel boron.
As of right now, I have a JARD adjustable two stage trigger in it. I'm not sure if I will keep it that way. I'm thinking about moving to a 3.5 pound single stage, and I'm especially fond of the flat triggers from Geissele. If they ever come out with that 3 position trigger, then that will be a no brainer. At some point I will play with trying to reduce the lock time. I would like to try using a titanium firing pin, but I don't know if I will be happy with the reliability. We'll just have to see how it holds up or if it spears my primers.
I also haven't decided what I want to do for optics. I'm leaning towards the Leupold Mark 8 1.1-8x, but also considering the 1.1-6x. I want a scope that can realize the potential of the rifle and still work in close quarters. I'm also considering doing a variable 10x scope with an offset RMR sight. I will have to play with it, and see what its practical range is. Part of me thinks that the practical potential for good terminal performance is about 300 meters or less, which would demand less scope. Again, I'm not trying to build a sniper rifle, and I have no illusions about the 5.56 being a long range cartridge. I know it can accurately go out to 600ish, but I'm rather dubious as to its terminal performance at long ranges. I'll just have to do more reading before I go throwing money at a new scope. Unfortunately I won't be able to give a good range report and grouping until I decide what glass to put on it.
So without further adieu, here are the photos.
http://i1300.photobucket.com/albums/ag97/hansthehobbit/DSCN0187_zpsbbplhmdi.jpg
http://i1300.photobucket.com/albums/ag97/hansthehobbit/DSCN0205_zpsbkapq1bn.jpg
Here's where I modified a redi mag to clear the VIS.
http://i1300.photobucket.com/albums/ag97/hansthehobbit/c31de70c-ed1b-446d-bf14-2b9e579c8b32_zpsibtnhthl.jpg
Vltor VIS Review:
I have nothing but positive things to say about the VIS. It was a breeze to install, it handles very well, and it makes a great platform for mounting accessories. It also has an extremely tight flange, which makes for a rock solid setup. Certainly no need to bed the barrel extension with this baby. To make installation easier, put your barrel in the freezer, then take a hair dryer to the upper. And lube up the barrel extension.
The best thing about the VIS is that there's no indexing the barrel nut, as the gas tube goes over it. So you simply torque it to 50 ft/lbs and that's it. The one inconvenience was that Vltor specifies using a particular type of anti-seize, as opposed to the usual moly grease (like aeroshell 33), and it's rather difficult to find. I was able to get it from amazon. Definitely don't use moly grease, as it will change the torque spec, and make sure that your anti-seize is safe for aluminum if you deviate from their brand of choice. They said the 100% copper from Brownell's was also acceptable.
The other thing is that you must use a reaction rod to install the barrel nut. A BEV block might work, but the reaction rod is far better, as you must be able to turn the rifle upside down to properly access the barrel nut. It's a very tight working space.
Lastly, to undo the tabs to remove the bottom handguard, you will need to make a little tool out of a punch. Simply bend the punch at a right angle, then use it to tap the tabs out. Works like a charm. Vltor says you can use a bullet tip, but I found that to be patently not true, at least when it's new. Maybe it will loosen up over time, but right now you will need the aforementioned bent punch. Just clamp the punch in a vice where you want the bend, about a centimeter or so from the tip, and bend it on over.