New Member, I recently bought a new S&W M&P PSX. I picked it up on Thursday and returned it on Friday For Two reasons, First there wasn't a spring on the bolt and Second all the parts that were advertised as being chromed(barrel bore, chamber, gas key, and bolt carrier) had the same coating as the rest of the gun. I know being chromed isn't the same as the chrome on a car bumper, but I didn't expect what I received. Smith&Wesson has emailed me saying that according to my serial number, my rifle was made in March of this year and no longer requires the bolt spring. Can anyone explain the design change? Any thoughts on the "Chromed" parts. Any thoughts on this gun Good or bad?

Spring on the bolt????? The only spring on an AR's bolt is for the extractor. Is that what your referring to?

In the owner's manual under the piston versions, it shows a spring onthe back of the bolt where it goes into the bolt carrier. It was not there on my rifle. Smith&Wesson said there was a design change and the spring was no longer needed.

From TOS here is your answer.

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Improvise, Adapt, Overcome

It sounds to me like they put the wrong bolt in it. the pics I have been able to find show a shiny chrome BCG is supposed to be in the PS and the PSX. Somebody messed up. I honestly feel bad for you but I know they will make it right.

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Grover Oathkeeper

Quote:
.if your purchase was recent, then you have Smith's new incarnation of Adams' Arms Piston set-up. Smith ditched the bolt tail spring and added bolt gas rings to stabilize the bolt in the BCG. Its certainly stiffer...and without the gas rings seemed to worked just fine. If you have gas rings on your bolt, then you have the correct set-up. Two improvements were made with their later uppers as well..... .18" hole for op-rod (as opposed to the bushing from earlier)...and your adjustable piston plug detent plunger is now captured by a tiny roll-pin (before it was held by a small stainless steel c-clip)...the c-clip would break due to extreme heat and recoil. Hope this helps.



Kodiakco,

What, or who, is TOS that you quoted from?? I have a 1 year old M&P15 PS that has the C-clip on the piston plug, as well as the spring on the bolt tail. I am going to write S&W tomorrow and see if I can get them to send me the upgraded parts, but I would like to know when and why these changes were first implemented in the PS & PSX guns. Thanks in advance for any information you can provide.

The Other Site. This place does not like it when you post links to other forums. FYI, I found the info on Google.

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Improvise, Adapt, Overcome

Thanks...I'll do some searching.

Sent you a message.

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Improvise, Adapt, Overcome

Thank you all for the feedback. Yes, according to the serial number my rifle was made in March of this year. I do have the pin holding the piston plug. I hope they make things right, it just sucks having to send your brand new rifle back after having it 24 hours and now having to wait another 3-??? Weeks to get it back because they were closed for 2 weeks!

Not trying to start another debate, but it's for reasons like this that I will continue to own gas impingement AR's until the industry gets the kinks worked out and standardizes on a single system.

Few things in our sports are more frustrating than needing a proprietary part and having to wait weeks or months to get it with the possible exception of finding your new firearm is already obsolete because of design changes.

Yep - if it breaks in the field, you're hosed and can't simply snap up another (discarded) weapon and strip parts out of it...

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*Aim small, miss small...

Once again I am new to this, but isn't the Adam's Arms piston system pretty much an exact copy of the AK piston system? I was also told with the Adam's Arms type system the gas rings have to be aligned just so or you wil experience malfunctions, if so, what is the secret to getting such alignment after cleaning?

you can spin them into place with a small pointy object.

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Grover Oathkeeper

I have the same issue. I just bought the rifle (PS) mid August of 2012 and when I field strip the BCG, the bolt does not have a spring as it is stated on fig. A20 on page 32 of the M&P15 manual. What I have is the one shown on page 25 fig. 24 and 25. I am waiting from a response from S&W as I contacted them lately. Let me know what you guys learned from this. Thanks.

This seems about correct as I purchased my M&P 15 PS OR rifle in June of 2012 and it did not come with the bolt that was in the manual... no spring, and bolt looked just like a DI bolt.... S&W said I would have to return my whole weapon for it to have the bolt without gas rings and to include the spring on end of ectractor.. That is some bull..... the parts you have listed are what are on my rifle and the piston detent selector.. is not a c-clip.. or atleast I do not think so... it is round and needs depressed to move to left for suppression or single shot..... I think S&W need to update their owners manual.. lol.. Thanks for the advice Imma leave it the way it is..