I have a Benelli M4 (M4 marked model) with the pistol grip factory stock.  I want to put a factory collapsible stock on it.  Is the buffer tube the same for both stocks?  ie. buy the collapsible stock set (it doesn't come with the metal buffer) and just "plug and play?"  - - or do I need to hund for another metal buffer to use in the system ?   Thank You.

If your M4 is the latest version with the cuts in the stock tube then a collapsible stock will drop right in.
 

If its the M4 with the American flag then no you can't.
The collapsible stock will only fit the 11707.
 

Inspect your receiver extension. See which one your M4 has. The M1014 and the 11703 models of the Benelli M4 both have the non-collapsible receiver extension shown on the bottom. All the newer 11707 and above M4's come equipped with the three position receiver extension.

The extensions can be replaced, but it is a big job. It takes a lot of heat to remove the extension.

do the extensions have to be indexed? I have to push the button and twist my stock till I get it to go into place, is this normal?
 

I have the 11707 easier than you think. and yes you have to have the 11707 tube or it will not work, your OEM stock is going to come off than you have to twist on the pistol grip till it's snug. than add your Cstock on it by putting it on the tube install to the left a little than up and to the right. than it's on.   and to use it yes Benelli is the only one it is not like an M4 rifle to use the stock you have to twist it to the right always to bring the stock up and down. I don't like it ether but. it makes the m4 look nice tho i love mine so far no problems just make sure you add things to it to make sure it is 922R. like I said unless your doing anything with the gun no one will ever know but. I like mine legal. carriercomp is who i use and I can tell you the workman ship everything the man touch's turns to gold. they just got the M4 Picatinny Rails in get them while he has them...     http://www.shop.carriercomp.com/category.sc?categoryId=5

Yes, the receiver extension must be indexed properly when reinstalled. Depending on where the notches are, that will dictate where the tail piece of the stock aligns. When I install them, I put the tail piece onto the receiver extension, then collapse it completely. I use the comb of the stock to act as a timing gauge. The comb should point to the center of the rear iron sight housing. Once it is in position, lock the nut down. Both the locknut and the receiver extension should be secured with locktite.

You do not want to screw the receiver extension in too far either.  You want the receiver extension to be flush with the inside of the receiver. If you thread the extension too far into the receiver, it will not allow you to screw on the pistol grip portion of the stock since it uses the external threads of the receiver extension to engage.

Pushing button is needed to adjust the stock. Without pushing it, you will meet a lot of resistance. You should press the button with your right hand thumb with your hand over the top of the stock body. Observe the witness lines engraved in the receiver extension. These will give you a visual reference point to where the engagement notch is.

Thanks, it looks like I have to get the heat gun out and redo the buffer tube as mine sits at a 35 degree angle.



I already have the Carrier Comp tube, hammer, bolt handle and the surefire rail to make mine 922 compiliant  


 

If you line up the flat spots kind of like how I have them in the photo, you should be close. The best is to use the collapsible stock as a index though. With it fully collapsed and engaged in the fully collapsed lock position, the comb of the collapsible stock should point right to the center of the rear iron sights.

Just make sure you don't screw the extension in too deep or you'll run into issues when screwing on the pistol grip portion of the collapsible stock. The extension should protrude into the inside of the receiver at all.

If you look at this picture of the M4 with the stock collapsed, it'll show you how the comb of the stock will point right to the iron sight housing. This will give you a near perfect index. When you put the tail piece on to do the indexing, don't install the pistol grip portion.