Sup everyone, got a quick question... Just got a great deal on a SW Mp15 sport but can't seem to find anywhere that tells me the stock size... I read that MP15's are all milspec except the version that is MA compliant. Problem is, is that I bought the one that is NJ, MA compliant and not sure if thats commercial or milspec. Can anyone with this rifle chime in? BTW this is my first AR and will be building this out so hopefully I'll be sticking around a bit

The mil spec measures 1.148 inches in diameter, and the commercial spec measures 1.168 inches in diameter.

 

problem is, is that I don't have the gun yet and my impatient a$$ wants to buy parts so it all gets here the same time    hopefully it gets delivered to my FFL this FRI.

contact Smith&Wesson if you dont get an answer here. They will be more than happy to help you out. 

Hold off on that stock purchase! If the gun was built as a AWB compliant, the buffer tube for that pinned stock may be a hybrid. Seems they use a rifle length stock tube with a metal retainer built in to shorten the inside of the tube to carbine length for the spring and buffer. Also most of these types have no milling in the underside for the "stops" on carbine stocks. You may have to replace the buffer tube with a carbine one. I have also seen AWB pinned "carbine style" stock setups using a rifle length spring and buffer assembly. Get the rifle first and post what type of stock assembly you have. We will help you figure it out, and what you need to build the rifle you want. Don't be in a hurry to waste money. Easy to do with this rifle setup!

 

Be aware there are different spring and buffers for the AR-15. Without knowing what you need, you could end up with a bad combination of parts.

Hold off on that stock purchase! If the gun was built as a AWB compliant, the buffer tube for that pinned stock may be a hybrid. Seems they use a rifle length stock tube with a metal retainer built in to shorten the inside of the tube to carbine length for the spring and buffer. Also most of these types have no milling in the underside for the "stops" on carbine stocks. You may have to replace the buffer tube with a carbine one. I have also seen AWB pinned "carbine style" stock setups using a rifle length spring and buffer assembly. Get the rifle first and post what type of stock assembly you have. We will help you figure it out, and what you need to build the rifle you want. Don't be in a hurry to waste money. Easy to do with this rifle setup!

 

+100

On the one I brought from Mr. Paul (PK90) which was NJ compliant I had to replace the buffer tube. I used a mil spec tube and magpul mil spec  CTR stock. The other stock would not come off the tube.

called CS and the guy states all the mp15's are milspec even the NJ compliant version. Not sure if I trust him though so I guess I'll wait until I get the rifle to avoid headaches. is there a way for me to tell once i receive it though without taking it apart?

What is your intent?  Replace the stock?  You will still need a new receiver extension.

What is your intent?  Replace the stock?  You will still need a new receiver extension.

yeah just to replace the stock with a magpul acr

You will need a new receiver extension also if you intend going shorter more than 3/4", so just get the one that is for the stock you get.  The buffer and spring can still be used.

called CS and the guy states all the mp15's are milspec even the NJ compliant version. Not sure if I trust him though so I guess I'll wait until I get the rifle to avoid headaches. is there a way for me to tell once i receive it though without taking it apart?

Yes, remove upper from lower. Hold down buffer retaining pin in lower and ease out buffer and spring. Now we need to identify buffer, it will tell us what type is it (carbine of rifle). A few measurements will tell you if the tube is reusable or not (probably not). Can't answer until you get a good look at tube.

Rifle Buffer..........

 

http://www.blackweaponsarmory.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/R/i/RifleBuffer.jpg

 

 

Carbine Buffer

 

http://www.blackweaponsarmory.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/C/a/CarbineBuffer.jpg

You will need a new receiver extension also if you intend going shorter more than 3/4", so just get the one that is for the stock you get.  The buffer and spring can still be used.

 

so i should be buying the stock with the kit instead of just the stock itself? I'm a newb so sorry if this is a stupid question lol

so i should be buying the stock with the kit instead of just the stock itself? I'm a newb so sorry if this is a stupid question lol

Yes you need to replace everything. At least that was my experience with one.

I have put mil-spec stocks onto commercial receiver extensions.  It needs to be persuaded with a hammer, but once in place, no pinning is necessary.

 

Again, if you intend on going shorter than the original, you will need another extension.  The buffer and spring should be the carbine length already,so no need to change them.

Yes you need to replace everything. At least that was my experience with one.

 

you had a NJ spec mp15?

I have put mil-spec stocks onto commercial receiver extensions.  It needs to be persuaded with a hammer, but once in place, no pinning is necessary.

 

Again, if you intend on going shorter than the original, you will need another extension.  The buffer and spring should be the carbine length already,so no need to change them.

 

i probably won't do shorter as I'm 6' and probably would feel more comfortable at stock length. But now I'm even more confused lol... I thought the extension and buffer were the same thing. And if I didn't want to go shorter does that mean I won't need to replace the receiver extension? And from a prior post someone said that this ar's stock doesn't come off the buffer tube. do you know this to be true?

My friend does. The buffer tube and stock need to be replaced like pk90 stated. Most kits you buy come with the spring and carbine buffer so we just replaced everything. Buying a tube and stock separate will cost about the same as a whole kit.

As far as I know, you can take the factory stock off the receiver extension (buffer tube) and still use it, but a new hole will have to be drilled for your new stock.  I suggest getting another receiver extension with your new stock and replace both.  You can still use the factory buffer and spring.

Hold off on that stock purchase! If the gun was built as a AWB compliant, the buffer tube for that pinned stock may be a hybrid. Seems they use a rifle length stock tube with a metal retainer built in to shorten the inside of the tube to carbine length for the spring and buffer. Also most of these types have no milling in the underside for the "stops" on carbine stocks. You may have to replace the buffer tube with a carbine one. I have also seen AWB pinned "carbine style" stock setups using a rifle length spring and buffer assembly. Get the rifle first and post what type of stock assembly you have. We will help you figure it out, and what you need to build the rifle you want. Don't be in a hurry to waste money. Easy to do with this rifle setup!

 

Be aware there are different spring and buffers for the AR-15. Without knowing what you need, you could end up with a bad combination of parts.

+1

As far as I know, you can take the factory stock off the receiver extension (buffer tube) and still use it, but a new hole will have to be drilled for your new stock.  I suggest getting another receiver extension with your new stock and replace both.  You can still use the factory buffer and spring.

 

after some research you are correct... here is a link on what someone did to replace the stock. http://www.ar15.com/forums/t_3_12/558792_.html 2nd post up from the bottom. Seems that all you really need to do is drill the existing hole bigger to fit the new l lever pin and all is well.

you had a NJ spec mp15?

I have the same rifle.  I installed the Magpul MOE Fixed Carbine Stock – Mil-Spec on mine.  http://store.magpul.com/product/MAG480/181

 

The original buffer tube was pinned to the stock. So I just ended up buying the Mil-Spec (Buffer Tube, Spring, Buffer, Plate Nut) Carbine Rifle Kit from (Ebay: 140957834270).

 

Here's the pic after the swap.  Pretty simple.

I brought my buffer tube off of amazon came as a kit $35. That castle nut was a bitch to get off though.

I brought my buffer tube off of amazon came as a kit $35. That castle nut was a **** to get off though.

Yup.  Scuffed up the castle nut pretty good on mine (as you can see on the pic above).  Good thing the kit came with a new one lol.

I have the same rifle.  I installed the Magpul MOE Fixed Carbine Stock – Mil-Spec on mine.  http://store.magpul.com/product/MAG480/181

 

The original buffer tube was pinned to the stock. So I just ended up buying the Mil-Spec (Buffer Tube, Spring, Buffer, Plate Nut) Carbine Rifle Kit from (Ebay: 140957834270).

 

Here's the pic after the swap.  Pretty simple.

so all you had to change was the buffer tube then right? kept the oem spring and buffer?

You are correct. In my case though I used the new spring and buffer with the new magpul stock. I really should have just bought the new buffer tube vs the whole kit lol. But I was trigger happy on buying new parts at the time as well.

 

Enjoy. Its a great rifle!

ok just finally finished and without all the trial and error it was pretty much a easy process. First off the hardest part of the process if you don't want to replace the buffer extension is taking the pin out. After an hour of trying everything i could and 3 broken drill bits I decided to just drill the other side and tapped it out from the other end. then the stock hole that the l lever goes in is smaller than the one from the acs so I drilled a 5/16th hole and it clicked right in. After that drilled and pinned and done! besides removing the pin part it was surprisingly easy. 

Hold off on that stock purchase! If the gun was built as a AWB compliant, the buffer tube for that pinned stock may be a hybrid. Seems they use a rifle length stock tube with a metal retainer built in to shorten the inside of the tube to carbine length for the spring and buffer. Also most of these types have no milling in the underside for the "stops" on carbine stocks. You may have to replace the buffer tube with a carbine one. I have also seen AWB pinned "carbine style" stock setups using a rifle length spring and buffer assembly. Get the rifle first and post what type of stock assembly you have. We will help you figure it out, and what you need to build the rifle you want. Don't be in a hurry to waste money. Easy to do with this rifle setup!

 

Be aware there are different spring and buffers for the AR-15. Without knowing what you need, you could end up with a bad combination of parts.

 

 

yet another reason to build your own AR15....

 

now here you are.. gun unfired.. and you are buying a bunch of parts that could have been purchased in the first place...

yet another reason to build your own AR15....

 

now here you are.. gun unfired.. and you are buying a bunch of parts that could have been purchased in the first place...

 

I took this advice for my Saiga's and AR and am very happy that I did.