Just picked up an M&P15, just the baseline one, and was wondering if anyone on here had any recommendations as to what drop in piston is the best? I'm not entirely sure I need, or even want, one yet, but I have generally speaking had better luck with pistons than DI systems in the past.

Thanks in advance for your help
-Brunt

OP
Without having actual sales and sell-through data in front of me, based on the amount of traffic and discussion I see, I think it would be a fair statement that Adams has taken the lionshare of the aftermarket piston kit business.

There are others of course who appear equally adept at producing a solid piston retrofit with their own particular spin on the concept of a piston AR.
The cautionary point on piston ARs is that each kit manufacturer has their own patented design. There's no STANAG format or COLT spec  as you find with DI guns. If it breaks, I can't necessarily be assured that I can pop into a local gun store and pick up a part or bolt.

So I pause to and consider how well tested and supported the kit maker is, who is backstopping their balance sheet which of course translates to how long will they be in business - or at least keep producing kits? If something goes snap or pop will I reliably be able to buy or find a part from them in 2 - 5 - 10 years from now?  

I feel a bit more secure with Adams because of their volume and proliferation. Additionally, one of the major manufacturers (I forget if it's Ruger or S&W) uses their piston design under license for their OEM black rifle. Being backstopped by a major manufacturer is a good thing. At least I know if it breaks and theoretically if Adams filed Chapter 7, I may be able to sources parts from the OEM.

for the price of that sport, right now you could have had a blemished complete gun from adams arms.

regardless i'd say since you already have the sport, leave it as is. no point in throwing a $300 kit at a $600 gun imo.

i can promise you it isn't ruger, they run their own less desirable piston set up. it may have been S&W, but they've since discontinued their piston offering so that's a moot point unless it happens to be a different manufacturer.

Hell I got an AA conversion kit from DSG when it was on sale couple months ago.

Im wondering what makes are the best, personally I have had bad luck with adams arms in the past. One of my buddies bought one and it malfunctioned consistently until it blew up, they sent him a new one and it worked better, but still jams regulary.

Im not saying adams arms are tierrible and im sure many of you have had good experiences with them, but I would personally like to steer clear of them. Ive seen a few other brands doing it like the 416 osprey kit. Which ones do you guys think are the best?

I guess i cant help, i have 2 AA piston  kits and they work great.

Adams Arms and Osprey both work well.  

One may shine over the other depending on your specific needs.

Why not, the M&P can be had for $529 shipped, go ahead and add the kit and have a piston AR that can always be converted back to DI if so desired.

Ares Defense has worked well for me.  Available in carbine length only.

I have had 4 Adams Arms units since they first came out and they are fantastic.  I outfitted one gun with an Osprey, because I wanted a stock looking AR, meaning the front sight. It has worked fine also, but I have not used it nearly as much as the Adams Arms systems I have, carbine, mid length and full rifle. Three are on 6.5 Grendel rifles, on on a 5.56.

I've got an 18" middy 5.56 and a 10.5" 300Bo pistol, both AA kits and both run like sewing machines.  Their customer service is as good as it gets as well.  Look through any post here about AA issues and without fail they are in there watching.  Not that you see much about any of the others but AA is the only manufacturer I see this from.  Lord knows they have helped me with several issues, half of which had nothing to do with their products.  I'm a very happy repeat customer.

Ruger only does piston guns, not drop in kits, and I'm curious why you find their systems less desirable?

Every one I've shot has run like a typewriter in the hands of a well oiled secretary.

I think the Ares and Osprey are the only two kits you can install without removing an A2 front sight / gas block as well, both are basically "drop-in" kits, but I'm sure someone will correct me if I'm wrong.

I'm interested in that as well. I'm also interested in finding out more about those well oiled secretaries...

Osprey...no bolts springs or valves and has a metered gas system drops in and comes off in 10 minutes I have 3 and on my main rifle 5 years over 9000 rounds and no problemsno carrier tilt either.

Can you explain the metered gas system ?

I have an Adams Arms on my 7.5" pistol and it runs like a top.  I bought the upper complete from Midway a while back when they had some deals on AA products.  I am probably about 1000 or so rounds deep(probably more) and I have yet to have any malfunctions with the pistol.  

I then tried the Osprey(NiB coated version) kit on my 10.5 pistol build which installed as advertised in about 10 minutes or so.  I wanted to keep the FSB and do an M4CQB/MK18 type build.  However when I took the gun out to fire, it would not cycle.  I then had to take the whole piston kit out, which took a bit longer than the install but still not too bad, and open up the gas port.  It seems as though either the gas port was too narrow due to the NiB coating or what I believe to be more likely, that the actual gas port was in the wrong position(a mm or less too far forward).  I have not gotten a chance to do a torture test with the gun since opening up the gas port but I did run a couple rounds through the gun and it cycled and seemed to be functioning.  If all holds up the gun should be a nice shooter but just something to keep in mind with the Osprey kit.  I have read this problem in some online reviews either here or on Midway or the like with the same problem happening when the NiB coated kit was purchased but not with the standard kit.

If you go Osprey just remember to put your old gas tube side by side with the Osprey included "gas tube" and make sure the ports of each are in approximately the same area.  I did this once I took the kit out and noticed the problem almost immediately.  If you can identify that before install you should have smooth sailing after that.  I actually was going to do this when I got the kit but with all the excitement of getting to tinker on an AR I forgot to do so.

I am running the POF roller cam and the "Reliabolt" in both guns.

What systems are available

Just curious, do you grind the sloth between teeth of barrel nut?
I have Osprey piston too and notice the chamber part is not inline with the upper receiver hole.
Use the grinder to grind the sloth about  down .080" to have chamber part inline with the receiver's hole.

i run the osprey system with fail zero coating on my 11.5" sbr love it, no lube no cleaning with the fail zero coating, only use wolf, probly 10k rounds no issues, be sure you buy a pof roller cam pin otherwise the original ar cam pin digs into the upper some, this probly goes for all piston systems

i run a gas block and to get the kit reliably functioning on wolf i had to increase the gas port in the barrel to the next size with a numbered drill bit, only very slight size increase, the gun ran fine on other commercial and mil spec ammo just short stroked on the wolf, has run fine ever since

this was the recommendation of osprey tech help

now if you install on a front sight post it will probly remove fine , gas block not so easy guess the tolorances on some gb are different

if the barrel nut is off a tad move the nut, or loosen and retorque, installed several of these have not had a barrel nut issue, except with free float tubes but those you just drill the hole to the size needed so there is no binding

Due to the chamber part is not in the same plane as the upper receiver' hole.
Required to grind barrel groove allows the op rod move freely.

See the link below.


https://www.flickr.com/photos/127575587@N08/15632287820/

I have a buddy whose di AR jams fairly often and I own an AA 5.45 upper that hasnt given me trouble save for those damn russian mil surp hard primers.

My point is small samples are pretty meaningless.  Don't get me wrong if I get burned or know someone that has been burned I tend to steer clear of whatever it was.

Looks like TNW dropped their drop-in piston system.

I am looking into the Ares piston system for future build.

I am done with them(TNW) and looking into the Ares piston system.

I am done with them (TNW) and looking into the Ares piston system.

The interesting thing about the TNW system is they claimed it was a long stroke piston.  However, on examination, while it had a longer stroke than most other short-stroke pistons, it didn't appear to stay in contact w/ the bolt carrier all the way to the rear as a long stroke piston would.

I'm a little curious why no one has made a long stroke piston system that just screws the piston rod directly onto the bolt carrier, replacing the gas key.

ETA:  looks like it's still on TNW's website:

http://www.tnwfirearms.com/product-p/sgpx-rgps-xxxx-nkxx-xxxx.htm

I'm partial to the FSB so I went with the Opsrey.  Ares (Bushmaster) also makes one that uses the FSB.  If you don't care about keeping the original FSB AA is the way to go for the reasons you suggested.

another vote for AA   !  i will admit im lazy , i hate to clean my guns . my AA runs dry and dirty and loves the crappy ruskie ammo . carbon fouling makes its owe kind of lube , lol . its fairly priced , easy to use , the weight is surprising balanced for a piston . my buddy has a H & K upper and that thing is a tank compared to my AA middy .


             dagg . . . . .