AR15 piston conversion, which are the good ones?

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First, yes I know DI is pretty reliable and the gun was designed for that.

Now that we have that out of the way, which piston conversion do you prefer? I've been reading about the different players in this market. Is a standard emerging?
 
No standards, no parts are interchangeable, pick the one you like and either buy spares or hope they are still in business if something breaks.

I chose a SCAR 16. FNs been around a while and the rifle was designed with a short stroke piston, not retrofitted with one.

BSW
 
I've thought of doing the same, but if I can convert an existing gun for $300-$400 and it is reliable and runs right I'd be happier than having to spend $2000 on a new gun.

I know there is something to be said for going with a piston gun design from the beginning.
 
For me the SCAR design eliminates a lot of weaknesses inherent to the AR design:

ARs break bolts- The SCAR uses a 6 lug bolt with bigger lugs and stress relief cuts.
ARs have minimal clearance for dirt- The SCAR has limited contact area between the rail and the bolt carrier.
ARs don't have adjustable gas regulators, one size must fit all applications- The SCAR has a field adjustable gas regulator.
ARs don't fold for compact storage or maneuverablity- The SCAR has a folding, adjustable stock.
ARs aren't ambidexterious- The SCAR is fully ambidexterious.
ARs can be less than reliable- The SCAR has numerous features that increase reliability in bad conditions. Very large bolt carrier mass, bolt carrier over travel, sealed receiver, dirt tolerant action, debris protected trigger group.

BSW
 
I looked into conversions and never found one I liked. I ended up buying an Hk MR556A1. I love the rifle and never looked back.

But I agree with briansmithwins the SCAR is the best choice for most. The only reason I didn't go with a SCAR is I love the AR design so much and I can interchange the uppers and lowers. My intentions now are a 10.6" 416 with an AAC suppressor. Right now they are about like finding hens teeth...
 
There used to be a long stroke conversion which I liked but I don't believe it's available any longer. Purchasing a PWS upper or rifle is the only way I know of today to get one. Of the available conversions Adams Arms seems to have the biggest following. I do like the Osprey design though. Personally though I wouldn't really rely on any of them as there just seems to be too many people who experience issues with all of them. While I know of no piston uppers for only $400 there are good ones available for well under $2K.
 
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There is zero reason to convert an AR. It works great as is and most any add on kit is going to be more prone to failure than the original config. Spend the money elsewhere, like a BCM bolt/ammo.
 
This...

There is zero reason to convert an AR. It works great as is and most any add on kit is going to be more prone to failure than the original config. Spend the money elsewhere, like a BCM bolt/ammo.
Click to expand...

is why I said, this.

First, yes I know DI is pretty reliable and the gun was designed for that.
Click to expand...
 
There is zero reason to convert an AR.
Click to expand...

I tend to agree. If you want a piston rifle (and there is nothing wrong with that), buy a rifle that was designed as such.
 
I tend to agree, I do have some short piston black rifles, but the gun was made to use with the direct impingement from gas. Accuracy is better with the fewer moving parts imparting a momentum on each shot.
 
Brian is right. My Hk is sub MOA out of the box (once you get the dang thing sighted in). They are all set at 6" low at 25 meters ?!? It shoots better than my M&P15 I just sold, but not as good as my RRA.
 
briansmithwins said:
For me the SCAR design eliminates a lot of weaknesses inherent to the AR design:

ARs break bolts- The SCAR uses a 6 lug bolt with bigger lugs and stress relief cuts.
ARs have minimal clearance for dirt- The SCAR has limited contact area between the rail and the bolt carrier.
ARs don't have adjustable gas regulators, one size must fit all applications- The SCAR has a field adjustable gas regulator.
ARs don't fold for compact storage or maneuverablity- The SCAR has a folding, adjustable stock.
ARs aren't ambidexterious- The SCAR is fully ambidexterious.
ARs can be less than reliable- The SCAR has numerous features that increase reliability in bad conditions. Very large bolt carrier mass, bolt carrier over travel, sealed receiver, dirt tolerant action, debris protected trigger group.

BSW
Click to expand...
how could any rifle be better then an AR?? lol. good post it looks like the SCAR is a much better rifle and with 50 years unlimited budget for the AR where all ammo and systems were tweaked they still did not address the shortcomings the SCAR did. I love a solid side folder
 
"AR15 piston conversion, which are the good ones?
First, yes I know DI is pretty reliable and the gun was designed for that.

Now that we have that out of the way, which piston conversion do you prefer? I've been reading about the different players in this market. Is a standard emerging?"

I am far from knowledgeable on these things.....

But, a friend/dealer of mine let me borrow a complete upper to play with, I mean test. I was all pumped, this was a completed upper made by a well known maker of gas piston conversions, not just a kit.

I mounted it on my lower and found it to be a very inconvenient bolt action weapon, one shot at a time followed with pulling the charging handle. It grouped better than I would have expected, for my first shots I was concerned with not shooting my chronograph and the latter ones were wondering why it would not cycle.

My analysis is that the gas block is not properly set over the gas port. The dumb thing is dead right there. As it isn't mine, I didn't attempt to adjust / fix the problem. Oh, I did pull the hand guard to see if the piston moved freely, it did. I pulled the 'in the gas block' part of the piston system and it was clean.... Too clean, no sign of any gas.

When I contacted my friend, I ask if the upper had ever been know to have functioned. No, he had received it in a business transaction and as it is chambered in 300 BlackOut and he has none, he passed it to me to try.

I don't think the way this one is put together, the adjustment process would be difficult. It's just that I didn't want to chance scuffing the barrel when moving the gas block about. If it was mine, it would be done.

I still think it is an interesting concept. A lot like pulling a fuel injection system off of a sports car and sticking a carburetor on. It will work and is an interesting challenge, but why?

So, I don't know who makes 'the good ones', nor do I have a preference. Like I said right off, I am far from knowledgeable on these things. But this is what I know and it isn't much.

I would still like to play with it, I mean test it.
 
But, a friend/dealer of mine let me borrow a complete upper to play with, I mean test. I was all pumped, this was a completed upper made by a well known maker of gas piston conversions, not just a kit.
Click to expand...

Okay, which one? There are countless positive accounts with a number of the piston AR's out there such as LWRC, LMT, sig and PWS. Just because one gun of one unknown maker was a lemon that in no way speaks to all designs on the whole. 300 black out has also had numerous teething issues in that it's been difficult to make one that will operate with all available loads.
 
JustinJ,

I decline to name the maker as this was a trade in weapon (ok, upper only) and I wouldn't want to characterize this major manufacture's products as being at fault originally. If I were to be in the market for this type of product, this is the maker I would look at first.

Sorry, no brand to be given. Can't blame the maker if some one has screwed up the upper. To me, an odd ball hand guard has been installed and I can see someone 'adjusting' things so they will fit under all of those rails. That is my first clue.

OR

friend/dealer: he has been a good friend longer than I knew he was a dealer. So if this is the "Okay, which one?", the answer is both.
 
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