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AR-556 MPR

90K views 108 replies 36 participants last post by  Sr40ken 
#1 ·
#14 · (Edited)
Here's a description on the bolt and carrier group:

Bolt is machined from 9310 alloy steel and is shot peened and pressure (proof) tested to ensure strength, structural integrity and durability.

Chrome-plated bolt carrier inside diameter and chrome-plated gas key inside diameter provide exceptional resistance to hot gases. The gas key is staked so that it will not loosen after extensive firing. A matte black oxide finish on the exterior of the bolt carrier provides corrosion resistance.

What type of "upgrades" were you wanting?
 
#25 ·
This new model is somewhat surprising given that the AR market is pretty flat. But it makes sense that Ruger would try to squeeze a bit more money out of and spark new sales of the AR556 line by offering a slight upgrade to the existing rifle.

My initial reaction to the 18in barrel and rifle gas was unfavorable. Nobody wants an oddball barrel length. But upon reflection the 18in barrel is probably a good idea. It shouldn't directly cut into the AR556 standard model market and it gives Ruger a somewhat unique product in the crowded AR15 market. This new model should appeal to those guys wanting a good inexpensive blaster for 3gun and similar action sports.

Questions I have:

Shrouded bolt carrier? Probably not but fingers crossed.

Why 4140 when Ruger is already using 4150 for the SR556 piston line?

Is there a "large frame" version in the works? I don't think it would be too far a stretch to see Ruger use the SR762 as a platform for a DI gas system in 308 and 6.5 Creedmoor. If Ruger can make such a rifle with features like the MPR without kicking the price up too far over the MPR they should be good to go.

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#28 · (Edited)
Why all the fuss over a shrouded firing pin?

The use of a 4140 barrel instead of 41v45 probably has to do with cost. And very little difference in function. Ruger stopped using 41v45 on their SR-762 in favor of 7120.
The 5R rifling and nitride treatment are the more important features, in my opinion. The rifle-length gas system is the cherry on top.
 
#62 ·
I ordered one on Monday, got it today (Thursday) and picked up at FFL. Fastest shipping I've ever seen for firearms.

Overall, it's great. Trigger Elite 452 works fine. Mine came in extra oily...

Upper & lower matched almost TOO well, very tight (almost no play/very little light passing through the gap). I have to use a punch to knock the takedown and pivot pins. Extra tight.

Non-staked castle nut. Slightly staked gas-key, will try to get pictures tonight.
 
#48 ·
Seems to me like the FA bolt would be cheaper/easier to machine. Less machining involved. I don't know why Ruger would go with the SA style. It wouldn't be a deal breaker for me anyway, for the $560 price I have seen the MPR at, but I would prefer the shrouded BCG.

LOL, I have already switched out the BCGs for my other two ARs, so I have a couple of FA spares laying around.
 
#51 ·
Got an email saying mine should be shipping within a day or two. Looking forward to it. I almost changed my mind and cancelled the order, but then I would go back and look at it and think "damn, that's a lot of gun for the money."
 
#52 ·
Picked up the AR556 MPR yesterday from the FFL. Spent an hour or so cleaning it up and lubing and inspecting. No visual flaws. Everything seems to function correctly. Now I need an optic. I have a Sig Sauer Romeo 5 on order. It will probably be a couple of weeks before I get to the range with it. I forgot how quickly the little things add up. By the time I mount an optic, sling swivels, and a sling, I'll have around $770 in it. And I'll, more than likely, want to add back up iron sights to it, so another 90 bucks.
 
#54 ·
It's true that the gas key is not staked in the traditional way that we are used to seeing, but it is staked. I think the standard AR556s have been staked the same way since the beginning.

Those that have contacted Ruger about it have been told that Ruger stakes them in a way that they won't come loose during use, but can be removed by a gunsmith if necessary. Not sure why you would ever want to remove the gas key, but there must be some reason.

I haven't seen any complaints on this forum about AR556 gas keys coming loose, so I am going to take Ruger's word for it and not worry about it.
 
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