S&W M&P15 PS Piston AR failure after ~1000rds and 8 years no cleaning.

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veprdude

New member
So I bought this rifle about 8 years ago. I bought it during the piston AR hype and never gave it the typical AR maintenance a DI gun would get. Fast forward 8 years and probably 1000-1500 rounds later I had my first FTF. The bullet was getting stuck on the feed ramp. Tried a few different mags with the same result. Pulled the bolt and there were aluminum shavings on the bolt. I didn't have any gun lube so I went through my truck and found some marine 2 cycle oil. Oiled up the BCG and it started running great again.

Before tonight, the only cleaning I've ever done was a bore snake down the barrel. No lube except what it came with from Smith & Wesson.

I treated this rifle half as a mini experiment to see if I could lock it up or when it would fail and half under the assumption that piston ARs are "zero maintenance" rifles, which they are not.

I figured that the point of failure would be the piston system gumming up and turning it into a single shot.

I don't really have a point to this except to share my experience in hopes that this information might be of some value to someone else. Going back out to the range tomorrow lubed and clean.
 
K

kozak6

New member
I honestly had no idea that S&W ever bothered with a piston AR.

Apparently, it was a licenced and modified Adams Arms sort of thing. Huh.
 
I

Ignition Override

New member
Interesting. How well might a typical S&W AR (same barrel length etc) do under the same test conditions?

As both a VZ-58 (-It’s Not an AK-) and AK guy, it’s nice to see how well various piston designs can operate.

How about ingesting ‘talcum powder’ dust in the Middle East?
 
D

Destructo6

New member
1000 in 8 years? What system did they use?

I've done 2,500+ in a plain jane M4 in 5 days with nothing more than a bolt wipe down and re-lube on day 3.
 
T

ttarp

New member
I didn't know S&W made a piston AR either, I'd be interested in seeing how soon an LWRC, Hk, or even a Wolf A1 upper would fail.
 
V

veprdude

New member
S&W doesn't offer them anymore. Not sure how many they made but they were around $1000 when DI guns were going for around 600-700. Yes it's built with the Adams Arms Piston system, which to my knowledge was one of the better designs for piston ARs.

The front gas block gets dangerously hot.
 
B

Bartholomew Roberts

Moderator
It is frequently easier to shoot 3,000 rounds over a couple of days with no cleaning than to shoot over 8 years with no cleaning. Stuff that isn’t going to be shot for several months needs to be cleaned before it is put away or you may have issues.
 
B

Ben Dover

New member
If there could have been any benefit to a piston in the AR system, Gene Stoner would have pt them in at the beginning.
 
J

jimbob86

Moderator
If there could have been any benefit to a piston in the AR system, Gene Stoner would have pt them in at the beginning.
Click to expand...

Two benefits to the piston system, Mr. Stoner or no: The bolt stays cleaner than a DI gun..... and the bolt and reciever stay cooler ...... Now Mr. Stoner surely knew this, but he obviously did not think sustained rapid fire would be required all that much.....
 
Z

zoo

Moderator
Good grief, the piston system makes for a substantially better AR. Is there really any question about that?

On the other hand, hey, DI are great for what they are.
 
J

jimbob86

Moderator
Good grief, the piston system makes for a substantially better AR. Is there really any question about that?
Click to expand...

"Better" is subjective. DI is always lighter .... that can be "better" for some people's needs.
 
D

DubC-Hicks

New member
Good grief, the piston system makes for a substantially better AR. Is there really any question about that?
Click to expand...

Actually, yes. Obviously there is, or else it wouldn't still be a debate. DI and piston guns have their own sets of issues. DI guns dirty up the internals and are designed to fail at the gas tube. Piston guns have carrier tilt (this can obviously be fixed), are heavier, have slightly more recoil, and are more expensive. Retrofitting piston kits onto AR platforms have also shown bolt lugs to break, as they weren't designed to unlock in such a way that the piston forces them to, especially in conjunction with any carrier tilt.

Google the Filthy 14 if you seriously think the AR15 DI system (which is in fact a piston, not a real DI) has any real issues, then reevaluate your decision.
 
T

ttarp

New member
The AR does fine as DI(or whatever you want to call it), at the point you actually see the benefits of a piston, there are other rifles(or GPMG's) much better suited than the AR for those extreme conditions.
 
P

pturner67

New member
I guess this puts a damper on all "what lube is best" threads. Apparently, 2-cycle oil and very rarely is the answer. :)
 
F

Fishbed77

New member
I treated this rifle half as a mini experiment to see if I could lock it up or when it would fail and half under the assumption that piston ARs are "zero maintenance" rifles, which they are not.
Click to expand...

No rifles are "zero maintenance."

Even AKs require lubrication.
 
D

dyl

New member
Saw this yesterday: someone representing a full-auto range in Nevada called Battlefield Las Vegas gave a report of what broke first in their rental guns. Renters *have* to use their ammo, and cannot bring their own firearms.

https://www.thefirearmblog.com/blog/2015/09/08/ar-endurance-findings-at-a-rental-range/

They don't use piston driven stuff anymore. Well, except for a "HK-416 “knock-off” TDI upper" whatever that means!

Interesting article, with what breaks first and when.
 
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