Vltor MUR vs Aero M4E1

[jrcii]

Hello All,

I'm gathering parts for a precision .223 build. Recently I started reading about still having a POI shift even with a free float hand guard. They're saying that because the rail interfaces with the barrel nut, pressure on the rail will put torque on the barrel nut and therefore on the barrel. I read a pretty good analysis that was showing about a 0.3 MOA shift.

When I started this project, I'd decided on a Vltor MUR and a Geissele MK8 because of the receiver's thick walls and the stiffness of the rail. But, now I'm thinking about the Aero M4E1 because the rail interfaces with the receiver instead of the barrel nut. I don't want to go with a monolithic upper, and this seems like the next best thing. The Aero combo costs about what you would pay for the Geissele rail alone, so that does kind of concern me as you get what you pay for.

So, given those two choices, which would you pick? I know that 0.3 MOA doesn't sound like much, but a semi-auto .223 is already going to be 'accuracy challenged' when compared to a bolt gun all other things being equal. So, I'd like to start with the best base possible. I'm not even sure that the POI shift is a universal thing or if it was just for that one guy. So, this whole thing may be immaterial.

I'd really appreciate your opinions on this one.

Thanks,

JRC

[C4IGrant]

Hello All,

I'm gathering parts for a precision .223 build. Recently I started reading about still having a POI shift even with a free float hand guard. They're saying that because the rail interfaces with the barrel nut, pressure on the rail will put torque on the barrel nut and therefore on the barrel. I read a pretty good analysis that was showing about a 0.3 MOA shift.

When I started this project, I'd decided on a Vltor MUR and a Geissele MK8 because of the receiver's thick walls and the stiffness of the rail. But, now I'm thinking about the Aero M4E1 because the rail interfaces with the receiver instead of the barrel nut. I don't want to go with a monolithic upper, and this seems like the next best thing. The Aero combo costs about what you would pay for the Geissele rail alone, so that does kind of concern me as you get what you pay for.

So, given those two choices, which would you pick? I know that 0.3 MOA doesn't sound like much, but a semi-auto .223 is already going to be 'accuracy challenged' when compared to a bolt gun all other things being equal. So, I'd like to start with the best base possible. I'm not even sure that the POI shift is a universal thing or if it was just for that one guy. So, this whole thing may be immaterial.

I'd really appreciate your opinions on this one.

Thanks,

JRC

I have had good experience with VLTOR products so can recommend them for sure. I have not used the AERO so I will not comment.

Another good option is the Mega billet upper receiver: http://www.gandrtactical.com/cgi-bin...n&key=M0304-HA


C4

[nova3930]

I used an Aero 8" 300BLK M4E1 upper on a rifle. The rail is only 7" but overall the thing feels super stiff. At least part of that is probably due to the 1.5" OD of the rail itself though...

[ScottW511]

I built up a shorty AR using an M4E1 10.5 upper. While it's not built as a precision rifle it shoots groups at 50 yards for zeroing just as tight as my JP VTAC. I like the design enough that I have the 308 version on order.

[RAM Engineer]

How do the Larue Stealth Uppers compare to Vltor, Mega or Aero? I prefer the clean looks of them vs most billet receivers.

[irondude]

I have a MUR Noveske upper receiver on a 20" precision build and it works as it is supposed to. I mates up well with a Noveske mil forged lower. Meaning it does not look odd like some of the billet uppers do on a forged lower. I am using a Noveske 16.7" NSR rail with a Proof Reseach Barrel. I am getting 3/4 MOA with 77 grain PRIME of Federal GGM.

[Eurodriver]

I am using a MUR on a 20" precision build as well. It does ok, I guess.

You do understand that .3 MOA of shift is the width of a TV remote control at 800 yards, right?

Hope you've got a Krieger Barrel and a $3000 optic.

[jrcii]

Good point.

JRC

I am using a MUR on a 20" precision build as well. It does ok, I guess.

You do understand that .3 MOA of shift is the width of a TV remote control at 800 yards, right?

Hope you've got a Krieger Barrel and a $3000 optic.

[MistWolf]

The MUR was tested and proved to be stiffer than normal flat top uppers and that was when it was made of 6061. Now, the MUR is made of 7075 which will make it even stiffer. Unfortunately, the threads where K.L. Davis tested upper stiffness has been stripped of its photos but here is a link to a thread that has links to the tests and a couple of other pertinent discussions.

https://www.m4carbine.net/showthread...per-Flex-tests

Short version is, the MUR is quite stiff and doesn't weigh much more than a standard forged flat top. I have one on a precision build using a Lothar-Walther 20" HBar barrel and am very satisfied with its performance. The MUR also allows the choice of any free float handguard, which is a must for me because I don't like aluminum for handguards. I don't know anything about the M4E1 upper but I can give my recommendation to the MUR as a precision upper, especially if a suppressor will be used

[Pappabear]

I use MUR and their monolithic pieces for builds. I have always been happy. I have a precision SPR with MUR and Noveske barrel. Its shoots sub moa but thats all I look for anymore in gas guns. I have gotten sloppy shooting small groups from too much work on steel. The MUR is probably your safe bet and fit and finish is very nice if you don't own one already.

PB