Stealth, MUR or Rainier Arms UltraMatch Upper

[jbsmwd]

I have deceided to built a new upper instead of just rebarreling my upper. So the question becomes which of these 3 uppers is the best one in regauds be true dimensionally and not put any stress/binding/torque on the BCG. I am concernd about the mechanical aspect not the looks of the upper reciever.

I have heard good things about the Stealth uppers being vey good, but I don't know much about the other 2 brands other then what I have read at their websites about tolerances.

The end goal is to build an uber realible upper. Which kinka puts the Vltor in last place with their F/A and deflector rivited in place. (corrected me if I am wrong)

[Hmac]

Vltor would be so sad to know that they are in last place. They think, and many agree, that they make the best uppers (MUR and VIS) available. As to FA/deflectors falling off, are you aware of that happening to anyone? I've never heard of that...

[TehLlama]

Stealths are fantastic. I haven't had problems with my Billet MURs. The Rainier would be great if you're certain you'll be using it with a BAD Lever.

A Forged upper in spec will be far more than adequate. Any of these would be fine, and work as an improvement. The Stealth's with a complete upper, or built by a smith are a fantastic value, otherwise I'd say if you're pulling parts from them, the best deal running would be the Rainier Upper (and all other rainier parts) and have Mr. Hwang and the lads up there make you an awesome upper.
Otherwise, just find ANY of these used (or a good forged one is more than adequate too) and go with that.

The quality of the barrel and chamber specs, mettalurgy of BCG will matter FAR more than what marginal help a billet upper might provide. There's play designed into the system, and it's there for a reason: any proper forged upper is going to be as good or better, there is certainly not $100 of performance to gain by moving up to one of these... this coming from somebody who owns two.

[Army Chief]

I've no direct experience (nor any overt interest) in the Stealth, but generally favored the MUR until the release of the RA. I've only had my hands on the latter for a month or so, but am sufficiently impressed so as to feel comfortable recommending it; especially if dimensionality is a major consideration.

I don't get the sense that this is quite the problem that some have made it out to be (depending upon the manufacturer), but there can be no doubt that Rainier has something special on their hands here.

Would post the same on your M4C mirror post, but you get the idea ...

AC

[jbsmwd]

I have not heard of any rivets falling/breaking off of the MUR but I consider it a weak point vs. sold molded F/A and deflector.

This is the first that I have heard of anybody saying thing about the RA receiver. So if there is marginal help in these types of receivers, who makes the best receiver that is forged and still dimensionally correct? Or should I just use the S&W M&P receiver that this will be replacing?
The parts that I have in mind are

Fail Zero BCG minus the bolt

Either the LWRC ACB bolt or AR Performance bolt I.T. 5.56-9310 alloy superbolt

And a receiver of which I am unsure what would be the best for my needs. (I normally what stuff that is strong and more reliable then what the market dictates)

As for the barrel I would love to get a hold of a CHF polygonal rifled barrel in stainless LW-50 that has been Ferritic Nitrocarburizing treated to increase surface strength and wear, but back down to Earth. I am not sure where to start; I only know that I don’t want a heavy barrel.

[Hmac]

I have not heard of any rivets falling/breaking off of the MUR but I consider it a weak point vs. sold molded F/A and deflector.

Yeh, I doubt that it's ever happened. And I can't imagine that it's a weak point. Me...I elected to go with a VIS upper because of the possibility of the bolts breaking and the rails falling off a conventional non-polylithic upper. I consider it a weak point of that design.

[Army Chief]

This is the first that I have heard of anybody saying thing about the RA receiver.

That is only to be expected, given that the RA upper is still quite new.

AC

[Stickman]

I've handled all three, and own multiples of the Vltor and RA uppers. I would consider the Vltor the strongest without question by nature of its forging and massive reinforcements. The Rainier Arms and Stealth upper would be both examples of well machined uppers. I wouldn't buy an upper that didn't have M4 feedramps, but thats just me.

[jbsmwd]

I think that I have narrowed it done to either the RA or the MUR. If I get the MUR it will be without the F/A for weight and I have never had to use it. Wish the RA had that option. Who really has to use their F/A?

Agreed the M4 feedramps are a most.


Thanks forthe help.

[Aragorn]

Who really has to use their F/A?

I occasionally have to use mine after performing a chamber check, as the spring is not always enough to return the BCG to full battery. That's the only time I've ever actually needed it. For me that's enough reason to always have one though, think about how much of a PITA it would be if you performed a chamber check and then had to cycle in a whole new round because it failed to go back into battery.

[Stickman]

Who really has to use their F/A?

Me, and on a regular basis. I don't use it for clearing malfunctions, but there are plenty of times that I have to chamber a round quietly as a city cop, especially at night.

Mine gets used a few times a week on average.

[jbsmwd]

Both of you made valid points that I did not think about - stealth and chamber checking. I was just thinking of clearing the chamber.


Stickman,

you do excellent work both in writing and photos, but d*mn I don't think I want to visit the city you work in. I will stick to the small town I live in.

[jbsmwd]

I just thouht of something, since I plan on building this upper myself what clamp/block (can't thing of the name of the tool that holds the upper in the vise) should I use if I go with either MUR or RA uppper receiver? Or are they disigned only for standard forged uppers?

[Hmac]

I have been told that many or most upper receiver vise blocks won't fit the MUR or VIS because of its thicker walls. That same person (a gunsmith who refers to himself as an AR15 "specialist") told me that the MUR's and VIS's are so rigid that you can clamp them top and bottom in a vise between two blocks of wood , torque on a barrel, and not change them dimensionally. Personally, I'd feel more comfortable using a vise block. I haven't had to disassemble my Noveske Light Recce w/VIS but I understand that the DPMS block (Panther Claw) works great for the VIS/MUR as well as other AR-15 and .308 uppers.

http://www.bravocompanyusa.com/AR15-...law%20ar15.htm

[TehLlama]

The FA isn't a really practical weight savings. If you want to cut weight, go forged, but that's not to say the MUR w/out FA is a bad choice. Being able to quietly chamber a round or perform a brass check is worth the minimal weight, absolutely.

Again, the advantage of the RA would be that you can order it assembled from the shop, and receiver block becomes a nonissue - RA will probably have a bundle with their upper and the Thunderbolt BCG's along soon enough.