I want to purchase the above item for my 870 so i can attach an Ace Socom stock.

From Mesa's site: "We even provide a specialized indexing end plate with an upper engagement claw to replace the standard lower dimple end plates. Users can add their own AR-15 stocks or grips as desired (note: AR stock support is limited to telescoping style stocks that do not require a lower receiver dimple for indexing)." ..."With the Low-tube adapters we have lowered the stock elevation by about an inch...which slightly limits the variety of buttstocks and grips supported. For example, only buttstocks that feature a receiver extension secured by an end plate can be fitted to the Low-tube adapters"

So my quesiton is, is the Ace socom gonna work with the MT low tube adapter?

If anyone could help i would greatly appreciate it!
thanks
diesel

I don't know, but if I wanted to know, I'd call them and ask them.  I prefer to get answers straight from the source.  But I bet somebody from Mesa will read this and answer you here.

As we attempt to explain on the website and in our catalog, the Low-tube design cannot accept stocks that require the use of the AR-15's indexing dimple.  Instead, any stock that has a groove cut into the ventral side of the receiver extension threads will work, because in that case you can use our special "claw" style end plate to secure the receiver extension tube.



An alternative, if you have enough threads in the tube, is to use two nuts together as a jam nut.  Standard nuts are usually too thick for two of them to be used in tandem this way, but ACE supply special short nuts for (apparently) exactly this application.



The ACE SOCOM is a special case.  The example we have here in the shop will not work with the Low-tube adapters because a) it uses a clamp that depends on the indexing dimple; and b) the threaded portion of the tube is only 3/8" long (!).  The following photos should illustrate this pretty well:



We run into the same problem with Magpul stocks.  We still don't understand why folks keep coming up with new ways to attach the stock to the rifle when the standard ways work so well.

Now we have heard from some customers that they have fitted ACE SOCOM stocks to their Low-tube adapters using the jam nut technique because their tubes feature much longer threads than the example we have.  This wouldn't surprise us, since the 3/8" thread length seems pretty short (the AR-15 specs ask for at least 1/2" of thread), so maybe ACE have changed their specs since we bought our unit.

Another way to make the ACE SOCOM stock work, which would be quick and easy if you have a mill, would be to machine the ventral groove in the threads.  Then you could use our "claw" end plate, assuming you had a short nut to tighten against it.

ACE SOCOM stocks (and Magpul stocks) work just fine with our High-tube adapters.

Two words: RED LOCTITE

Quoted: Two words: RED LOCTITE

Yabbut you have to remove the receiver extension tube to get to the adapter's receiver bolt.  Not recommended.