A year ago it's all that was talked about, now not much at all. Guess it wasn't all it was cracked up to be.

When the Bushmaster ACR(Magpul Masada) rolls out it will be the new benchmark.  

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Quoted: When the Bushmaster ACR(Magpul Masada) rolls out it will be the new benchmark.

Off topic but why did Magpul partner with Bushmaster ref the Masada deal? Couldn't Magpul make a fine rifle without Bushmaster putting any effort into it?

I will state this again but I must say I do not take sides on the issue...

I owned a HK SL-8 which if you ever looked at the design, is a gas piston setup. The bolt head looks like it would fit in a AR. Anyhow , that thing would not get dirty, all the fouling stayed up by the piston. The bolt just took a quick wipedown to clean, I thought that was pretty good feature.

In the current geo-political climate the rave has moved away from non-barrier penetrating / background friendly pistol ammunition to the more rounded 5.56 round.  The rifle round offers better penetration and the ability to defeat body armor.  That coupled with better long range accuracy is the reason why so many SWAT teams are moving from MP-5s to AR15s.

Frankly, I love the idea of a 9mm AR.  Cheap plinker gun with decent 100 yard accuracy, but only if I already have an M4.

Quoted: In the current geo-political climate the rave has moved away from non-barrier penetrating / background friendly pistol ammunition to the more rounded 5.56 round.  The rifle round offers better penetration and the ability to defeat body armor.  That coupled with better long range accuracy is the reason why so many SWAT teams are moving from MP-5s to AR15s. Frankly, I love the idea of a 9mm AR.  Cheap plinker gun with decent 100 yard accuracy, but only if I already have an M4.

He's asking about Piston uppers not pistol uppers.  

As of right now there are a ton of pistons systems out there and none tested well enough to prove the flaws I see in it, time will tell.

Flaws I see

1.  Since the carrier key is tapped after prolonged use how does the off-center push from the top affect carrier wear, bolt face wear, star chamber wear.

2. Does the exposed piston in may upper kits capable of functioning in all weather especailly cold and wet.

3. Accuracy effects caused by the extra moving parts

the last one is really just for me and does not apply to civi use.

4.  I was in the Airborne and have had more than one bad PLF, I have broken handguards and seen many other troopers break handguards when they land on the weapons case, (odd that I have only seen a buffer tube break once but handguards always.) I want to know if the piston rod will still work if bent a little I can tell you that a little bend (not a kink) does not effect DI, but a little bend could really FU a piston I think.  Much of this would be combated with RAS which would better protect the piston but the question is still there.


As far as the fact we talk about piston uppers less, mostly they are too expensive for the extra pleasure, second until the .mil adopts one most think its just another fad (same apllys to 6.8 SPC)

There's a great review of a piston conversion around here somewhere.....he said the recoil impulse was slightly but noticeably "sharper".

My opinion is that they're not that big a deal.  I just don't see it being that great an improvement over the DI system.  I don't look at my AR and think, "damn, this needs a piston upgrade!"  Granted, it does seem to keep the weapon a little cooler, in extended firing, but I say.....big deal......