Any experience with the SIG SAUER 516 AR-15 or variant?

I have the Sig 556 and LOVE it. There is no muzzle rise at all in quick fire. I can fold the handle over and treat it like a pistol (I don't) without interfering with controls--no buffer tube, of course. I have a Bushmaster that's piston. It was my first and one of the first to come out. I have moved that upper to an S&W AR and, as you'd guess, it works fine. That's one of the great things about the removable pin upper/lower on a standard AR. The bolt does stay noticeable cleaner on a piston system. I don't feel any difference in recoil but the "feel" is more linear on the piston ARs to me. A major poster here has said that the piston is a solution looking for a problem. That may be true as the press sometimes poses it. But I see it as a nod to AK functionality. Neither direct impingement nor piston would make me buy or not buy a given gun (after I bought the first to try it). The Sig is now my favorite 5.56 AR. (The Springfield Scout M1A is still my favorite rifle.) I even bought the 522 for my wife and I to plink as a nod to how much I like the 556. I haven't had hands on the 516 yet.

I don't own a SIG 516, but own the SIG556 w/ folding stock (the semi-automatic version of Switzerland's heralded SIG SG550). But frankly, there isn't much of a difference between these rifles, upon examination. AR-15 has been done to death. Let it go. Slapping a piston on it doesn’t make a new gun and it won’t change squat. It is not revolutionary, rather I think it’s about being evolutionary. Having said that, about one of the the most trusted firearm manufacturers out there making their version of the tried and true AR15 is SIG. And SIG has been known for very tight tolerances in their manufacturing process. About a year ago, after purchasing my SIG556 I got exceptional MOAs out of the box...on paper and have improved it ever since. Over the course of a thousand rounds, there was not a single malfunction ( I used Blackhills, Winchester and Federal ammo). I have owned several Sig weapons over the years and have never found any flaws (SIG pistols P225...P226). For many other cosmetic differences, the SIG556 lower receiver is manufactured from 7075-T6 forged-aluminum alloy rather than pressed steel like its Swiss sibling, reducing overall weight by about a pound. Barrel twist is 1:7-inch RH twist giving more choices in ammo.

I once ran into a friend (at the airport) who had been to the 2010 SHOT Show in Las Vegas, and he said that SIG had their new piston operated 7.62 NATO/.308 rifle at the show. It will be called the SIG 716. However, it will not be available to the U.S. market for another year. It will come in two barrel lengths, the Precision Sniper (20" barrel) and Precision Marksman or Patrol (16" barrel) . The latter barrel length is the rifle I am going to purchase next to complement my SIG556 and S & W M&P15-T.

You cant. Only full auto machine guns that were in the 1986 NFA data base when it was sealed - can be legally transfered to a civilian. Back then a full auto M16 ower was $65 and $200 tax stamp, and, a full auto Mac-10 was $395 plus the tax stamp. Today, that same lower is worth $9,000 to $18,000 and that Mac-10, even after being fired, used and abused the past almost 3 decades - is $4500 used. Now. Even if you did know 'someone' who sold you or traded you for some used full auto internal parts - they are not hard to get - your AR-15 doesnt have the holes for the full auto parts. You would need to get your hands on real full auto, and, have a skilled machinist put the holes in......... not someting many people are willing to do since the jail time and fine is extra odinary. If you live in one of the 39 states that allow full auto - you can buy one - assuming you have $10K+ handy, and, a clean record, and the local chief of police will sign off on it. Now - that said - a better solution is a SBR - Short Barrel Rifle. Because I have been around allot of full auto firearms - and - 90% of the users/owners dont hit more targets going full auto, they just run out of ammo faster. With a SBR - you have a 10" barrel and usually a 6" suppressor - this is a very small and quite potent AR-15 in close quarters. I built one for doing tactical drills and love the little bugger. I did have to pay the $200 tax and wait 7 months - but it was money and time well spent. It's small like the full autos, very accurate, and doesnt run out of ammo in 2.1 seconds. Conversion - not a good idea. It would only get you in trouble.

If it has a piston, it isn't an AR15...

Direct impingement is what an AR15 is supposed to run with. If you want a piston, buy an AKM clone.

Are you shooting with a suppressor? If the answer is "yes", consider a piston. If the answer is "no", then it is totally unnecessary.

My boss has had me clean his LWRC rifle from time to time when he doesn't want to.... And I can tell you it gets dirty just the same.

The AR15 actually vents the gas from operation out of the rifle. It isn't just dumped into the receiver as some claim. Most of the debris built up in the receiver comes from the breech when the cartridge casing is extracted.

Piston guns still have to extract the case, and still get a lot of build up in the receiver from this.

Running a suppressor increases the back pressure, and makes it about 10x worse.

Most of the piston "AR15"s also have serious issues with carrier tilt that beats up the upper. The AR15 has no rails for the bolt carrier to ride on because it doesn't need them. The force is centered, so it doesn't try to cant in the upper. When you add a piston, the forces are no longer centered, and it flops around all over the place.

They're just not worth it.... They're heavy, non-standard, have more parts, and provide no benefits.

Direct impingement is reliable. Pat Rogers ran his Colt 6940 for 17,600 rounds (no cleaning, only oil) without chronic failures, and only replacing the extractor. The bolt is only rated for 10,000 rounds. Barrels enter the range of possibly exceeding their life at 15,000.

Pistons are obsolete technology... Let it die. Direct impingement is the modern system.