I'm interested in a comparison of the two- strengths/weaknesses of each, recommendations.

On the outside the M&P15T and the AR-556 are similar rifles - flat top upper, 10" Troy quad rail & Troy flip-up BUIS, 16" barrel, M4 collapsible stock. Underneath they're quite different primarily because of their gas operating systems.

The S&W utilizes the standard, battle proven direct gas impingement system whereas the Ruger utilizes a proprietary 2-stage gas piston system. While retrofitted gas piston systems can offer some benefits in the AR platform there are still quirks to be worked out (some research online is recommended before choosing a piston operated AR). One of these, bolt carrier tilt, has become a concern for AR-556 users. It's believed that stacked tolerances may be the reason a percentage of the Rugers exhibit carrier tilt and unusual receiver and buffer tube wear as a result. One more factor worth noting - gas piston systems for the AR are relatively new and there's no one standard design. If a part in a piston system fails then replacement parts from that piston system manufacturer will be required to repair the failure (some are young coompanies with uncertain futures). In contrast replacement parts for a standard direct impingement gun are available everywhere and are standardized.

The M&P15T's barrel is free floating potentially increasing accuracy. The quad-rail forend is also free-floating and is tightly clamped to the barrel nut. The Ruger's quad-rail forend is affixed to both the upper receiver and the adjustable gas block via steel roll pins. The downside to this design is that direct contact with the gas block can cause the aluminum rail to become hot to the touch after emptying a few magazines.

I'm glad to see Ruger making AR's. I'm just not very confident in the product in its current form. I expect they'll work out the isues with time and experience.

That's my $0.02

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M&P15T M&P9 M&P9c SW1911 4506

I have owned the M&P "VTAC" version for 4 months and am completely happy with its performance...this is my favorite rifle...even more than my 3 Weatherbys.

Google..."Ruger SR556 Extraction problems" for the latest news on this problem & possible fix. Ruger's AR15 line is a "one only" version compared to the M&P15 line has atleast 12 versions!

I'll add that after considering a variety of AR's, including the Ruger, I purchased a M&P15T and couldn't be more pleased with it. It's easily my favorite rifle of any I've owned. My favorite handgun is also a Smith & Wesson, a 4506. Like the M&P15 it's tough, 100% reliable, very accurate, and fun to shoot!

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M&P15T M&P9 M&P9c SW1911 4506

Thanks for the input, guys.

Well, I bought a M&P15 yesterday, M4 configuration with removable carrying handle. S&W's 5 free P-mag offer was a nice extra. Can't wait to try it out.

Congrats on the M&P 15. Where in SW OH do you shoot?

I'm a member at Butler Co Sportsman's Club, but a lot of the time, I just use the range at the prison where I work.

Congratulations!

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M&P15T M&P9 M&P9c SW1911 4506

I know it’s not what you asked, but why not buy a Colt?

I don’t think you can go wrong with either a 6920 or 6940.

Emory

I was having the same debate as you. I decided to go with the M&P 15T. I'm not really up on the piston driven stuff yet by Ruger but who knows new stuff does scare people sometimes. The Ruger also has a little more weight to it considering the barrel type.
I not knocking it at all, I just preferred the lighter M&P considering once you start adding items on. I don't think you can go wrong with both rifles. My favorite saying is you can never own to many rifles so hey I might purchase one in the future.

I prefer lighter weight as well. The rails, folding BUIS and whatnot are kind of nice, but I decided they were not really something I particularly needed, especially at $500 over what I paid for the M&P that I ended up buying.

I have the 15T and the 15R and found both to be some of the best ARs I own. The 15R has become my favorite plinking AR and works well with the Cproducts mags.
I looked at the Ruger, but couldn't justify the high price tag. Plus its new and it something breaks in a year or 2 will you be able to get parts?

IMHO,
The only thing I dont like about any AR chassis including the 15-22 is the scope height, I would like to be no more than 1.5" above the bore. Havent scoped mine but it looks to be not that bad...we'll see.

The SR22 looks like they added an even higher elevated rail for looks, not the best for point blank ballistics (rimfire: close range targets=holdover).

Hard to beat S&W customer service. I also am not sure about the gas piston thing. Lots of different ideas on that, some will work, some may not or may not be all that durable.
What one does know is that the AR platform is very well tested and proven. It is not perfect as no rifle is. Personally I've never jammed one up due to fouling. I'm not planning to deploy to the middle east anytime soon so I think it will serve my needs.
I ended up with a Rock River in an M4 pattern and also have a Colt Match Target with an extra White Oak Armament varmint upper. Love ARs, just awesome rifles.

The review I read in one of the gun mags. noted that the Ruger must be returned to Ruger for adjustment/repair of the gas system, as gunsmiths were not authorized by ruger to service it. I thought that rather interesting.

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Gimpy, grouchy and gouty.

S&W has two new piston AR's set to hit the market any day, the PS and the PSX. They use the Adams Arms piston system.

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John