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

veprdude · December 9, 2019, 12:26 AM

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.

kozak6 · December 9, 2019, 03:22 AM

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.

Ignition Override · December 9, 2019, 04:20 AM

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?

Destructo6 · December 9, 2019, 08:25 AM

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.

chuck jones · December 9, 2019, 03:08 PM

I guess it needed some lube after 8 years, huh?

ttarp · December 9, 2019, 05:04 PM

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.

veprdude · December 9, 2019, 05:20 PM

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.

bfoosh006 · December 10, 2019, 10:45 AM

Good info on your S&W PSX ( ? )

A few photos...
https://www.smith-wesson.com/firearm...model-mp15-psx

https://www.thefirearmblog.com/blog/...-piston-ar-15/

Bartholomew Roberts · December 10, 2019, 07:27 PM

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.

rickyrick · December 10, 2019, 08:05 PM

Only 1000? I’ve done that in a morning.

Ben Dover · December 10, 2019, 08:05 PM

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

jimbob86 · December 10, 2019, 08:38 PM

Quote:

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

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.....

zoo · December 10, 2019, 10:08 PM

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.

jimbob86 · December 10, 2019, 10:58 PM

Quote:

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

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

DubC-Hicks · December 11, 2019, 03:46 AM

Quote:

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

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.

Fishbed77 · December 11, 2019, 11:56 AM

Quote:

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

Facts pretty much kill this argument.

ttarp · December 11, 2019, 01:06 PM

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.

pturner67 · December 11, 2019, 06:44 PM

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

Fishbed77 · December 12, 2019, 10:17 AM

Quote:

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.

No rifles are "zero maintenance."

Even AKs require lubrication.

dyl · December 12, 2019, 05:27 PM

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/...-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.

Ben Dover · December 12, 2019, 05:44 PM

That doesn't surprise me. There is no need or reason for the piston. Gene Stoner knew what he was doing.

December 9, 2019, 12:26 AM	#1
veprdude Senior Member Join Date: March 18, 2019 Location: Texas Posts: 430	S&W M&P15 PS Piston AR failure after ~1000rds and 8 years no cleaning. 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.

December 9, 2019, 08:25 AM	#4
Destructo6 Senior Member Join Date: March 18, 1999 Location: Nogales, AZ USA Posts: 4,000	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. __________________ God gave you a soul. Your parents, a body. Your country, a rifle. Keep all of them clean.

December 10, 2019, 08:05 PM	#11
Ben Dover Senior Member Join Date: April 11, 2013 Location: High up in the Rocky Moun Posts: 665	If there could have been any benefit to a piston in the AR system, Gene Stoner would have pt them in at the beginning. __________________ The soldier's pack is not so heavy a burden as the prisoner's chains. Dwight Eisenhower It is very important what a man stands for. But it is far more important what a man refuses to stand for.

December 12, 2019, 05:44 PM	#21
Ben Dover Senior Member Join Date: April 11, 2013 Location: High up in the Rocky Moun Posts: 665	That doesn't surprise me. There is no need or reason for the piston. Gene Stoner knew what he was doing. __________________ The soldier's pack is not so heavy a burden as the prisoner's chains. Dwight Eisenhower It is very important what a man stands for. But it is far more important what a man refuses to stand for.

December 9, 2019, 03:22 AM	#2
kozak6 Senior Member Join Date: June 16, 2005 Location: AZ Posts: 3,113	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.

December 9, 2019, 04:20 AM	#3
Ignition Override Senior Member Join Date: February 18, 2008 Location: About 20 nm from the Big Muddy Posts: 2,886	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?

December 9, 2019, 03:08 PM	#5
chuck jones Member Join Date: July 9, 2011 Posts: 16	I guess it needed some lube after 8 years, huh?

December 9, 2019, 05:04 PM	#6
ttarp Senior Member Join Date: January 4, 2013 Posts: 888	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.

December 9, 2019, 05:20 PM	#7
veprdude Senior Member Join Date: March 18, 2019 Location: Texas Posts: 430	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.

December 10, 2019, 10:45 AM	#8
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	Good info on your S&W PSX ( ? ) A few photos... https://www.smith-wesson.com/firearm...model-mp15-psx https://www.thefirearmblog.com/blog/...-piston-ar-15/

December 10, 2019, 07:27 PM	#9
Bartholomew Roberts member Join Date: June 12, 2000 Location: Texas and Oklahoma area Posts: 8,462	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.

December 10, 2019, 08:05 PM	#10
rickyrick Senior Member Join Date: March 15, 2010 Posts: 8,237	Only 1000? I’ve done that in a morning.

December 10, 2019, 10:08 PM	#13
zoo member Join Date: October 2, 2019 Posts: 414	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.

December 11, 2019, 01:06 PM	#17
ttarp Senior Member Join Date: January 4, 2013 Posts: 888	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.

December 11, 2019, 06:44 PM	#18
pturner67 Senior Member Join Date: February 26, 2006 Posts: 737	I guess this puts a damper on all "what lube is best" threads. Apparently, 2-cycle oil and very rarely is the answer.

December 12, 2019, 05:27 PM	#20
dyl Senior Member Join Date: October 31, 2009 Location: Ohio Posts: 1,310	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/...-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.