Around a year or two ago I purchased a M&P Sport 15. So far I'm really liking it. However, I live in NJ where the stock needs to be fixed and cannot be adjustable, collapsible or folding or whatever..

Anyway, I'm not very tall so I would like to bring the stock closer to the upper for a better fit. In order to do this with a NJ Complaint M&P Sport 15 would have to also replace the buffer tube, buffer spring and buffer? Or do I remove the roll pin, slide the stock down and then pin the stock in another spot?

Thanks...

I dont know about your sport, but on my 15-22 i just removed the roll pin and the stock slid back and forth. I also replaced the buttstock with a Magpul MOE. Just a reminder, you will be breaking the law if NJ calls for a fixed butt stock, so beware.

Gary

You don't want to move that stock in closer. The reason NJ has it pinned out to the fullest extent is so that it makes it harder to conceal. If you get caught jail time is likely. I get why you want to do it, but don't.

Ok, but what if a NJ resident builds an AR with a ACE skeleton stock? Actually I was sort of planning on just removing the OEM stock along with the buffer tube and replacing it with a 7 1/4" ACE Skeleton Stock.

I do not have a NJ compliant rifle, but if I remember correctly, you would have to replace the receiver extension (buffer tube), as the NJ compliant ones do not have the additional holes drilled to change the stock position... either change it, or possibly drill a hole for the locking lever in the new position.

As long as the overall rifle is over 26" in length.

rojasj,
I have an M&P15-FT (Fixed stock T model). The buffer tube/receiver extension that comes with the FT (I'll assume all the other M&P fixed stock models are the same here) has a mil-spec diameter but is longer than the commercial and mil-spec tubes. They are bored out to the same depth of a commercial / mil-spec tube so no need for a new buffer or buffer spring.
Even if you unpin the stock there will be very little movement on the tube. Look at the end of the stock, you will see that the tube end is about 1/2-inch below the butt surface. Also, there is a threaded hole for the "adjustment lever pin" to fasten that fixes the stock's adjustment. I have no idea why there is a roll pin except to make it look "pinned" in those states under 2A tyranny.
I would purchase a new milspec carbine buffer tube; forged 7075 preferably. Then purchase a new mil-spec fixed stock like the Magpul MOE Fixed Carbine Stock MAG480 or pin an adjustable stock to the new carbine buffer tube.
I "pinned" a MOE stock by removing the adjustment mechanism and inserting a Magpul dummy round. The .223 round "coincidentally (?)" fits within the MOE stock and with a slight taper will fit in the adjustment holes of the carbine buffer tube. This also stops the rattle that occurs with adjustable stocks. Makes for a strong installation too over a small pin.

M&P15-FT stock and S&W proprietary length receiver extension/buffer tube.



MOE Carbine Fixed Stock installed with new Carbine Buffer tube and Troy sling mount:

I "pinned" a MOE stock with Magpul dummy round.
I stole the idea from someone who used a .223/5.56 brass case.



Note the alignment of the "MAGPUL" script to give a 'factory' appearance.

What is your overall lenght of the carbine?

On the M&P15-FT with the Magpul MOE Fixed Carbine Stock (MAG480) + PRS Extended Butt-pad (MAG350) installed I get 33-5/16" down the axis of the barrel to the buttpad. The MAG350 installed adds 0.80" ( ~13/16") to the length. The factory S&W pinned stock is a bit longer.

rojasj, What did you end up doing?

I had to end up buying two tires for my car as well as a brake job. SO sadly the stock will have to wait a few months. Probably till the start of the summer.

But you guys gave me some great info.

I HATE it when real life interferes!

I love your idea. I recently picked up a Sport II and would like to change the stock as well. Is removing the adjustment mechanism a permanent modification or can it be put back if I move to a "free" state?

The stock can be returned to normal without a scratch.

What does a collapsible stock have to do with gun laws in your state?

The OP lives in New Jersey, one of the most draconian anti-second amendment States in the country. A collapsible stock is an "assault rifle" feature.

Well said.

In Ct, They do the same thing PLUS you can NOT have a Bayonet mount on your AR either :O

__________________
9mm Shield

I'm gonna try Engine Earl's method. Is there a particular brand buffer tube that is better than another?

Yes, because so many gang bangers and bank robbers use fixed bayonets in their crimes.

No, not really. I prefer that the retailer explicitly/specifically mentions that the receiver extension/buffer tube is made of 7075 aluminum, not 6061 aluminum. The one in the pic mil-spec, 7075 from ALG Defense.