New to AR's I have a question

[bpowell333]

My wife bought me this for Christmas.
Is the M&P Sport II mil spec or commercial spec?
I was wanting to change out the stock.
Also what is a good quad rail to get?

 

[agksimon]

My wife bought me this for Christmas.
Is the M&P Sport II mil spec or commercial spec?
I was wanting to change out the stock.
Also what is a good quad rail to get?

They are definitely mil-spec. I changed out my stock too.

 

[bpowell333]

Thank you.
Happy New Years!!

 

[jagular]

Welcome and congrats on your first AR. Search the forum for the answers you seek. There a probably hundreds of threads on these topics.

 

[Rastoff]

Is the M&P Sport II mil spec or commercial spec?
I was wanting to change out the stock.

This question, when talking about any AR, can have a two part answer. What you're most concerned with is the buffer tube. In this case it is Mil-spec. The way to tell is by the diameter. A Mil-spec buffer tube is 1.148" in diameter and a Civ-spec is 1.168" in diameter.

That is the measurement you're most interested. They are also made out of different materials, but that isn't really material (see what I did there) to your question.

Also what is a good quad rail to get?

None.

Maybe that seems blunt, but the quad rail is falling out of favor. Let me explain...

An uncovered MIL-STD-1913 rail, or Picatinny rail, is not comfortable to hold on to. The only reason to have a forearm with 4 1913 rails is to add a bunch of stuff that attaches to the rail. In recent years there have been two additions to the forearm attaching methodology; the Key-Mod and M-Lock.

Key-Mod looks like this: (note the key holes)

M-Lock looks like this: (note the rectangular holes)

The M-Lock seems most popular, but all three are still plentiful. The benefit of Key-Mod or M-Lock is that when there is nothing on the forearm, they're still comfortable to hold onto.

Now, the Sport II comes with what's called a "drop in" rail. This means it is held in by spring tension from the Delta ring. This makes it easy and inexpensive to change, but not nearly as stable as most like.

A really good, drop in, quad rail will run about $75 or more. However, a decent free float forearm, can be had for about $120. Better and more stable.

 

[CH4]

Be careful, it's a slippery slope...

 

[WR Moore]

While I don't have any experience with the Sport series, while working, the M&P15 was one of the brands of our carbines. Those had commercial dimension buffer tubes/receiver extensions. And we had a lot of them.

Before buying replacements, you might want to actually measure the tube diameter.

As noted above, there's no significant difference between the mil-spec and commercial versions unless you're going to swap stocks.

About rails..... the original design spec for what became the M4 was under 6 lbs with a loaded 20 round magazine. Given 40+ years of product improvement and mission creep, you're hard pressed to find one under 8 lbs. You really don't need to make it easier to hang ever more weight-beyond maybe a weapon mounted light and optical sight of some type-on it. If the current hand guard doesn't have a heat shield, you might want to look for one that does. Unless you shoot across the course bullseye competition, don't bother with a free float hand guard.

 

[sgtsandman]

Welcome to the forum! You got the answer you needed to both of your questions.

In my opinion, I would avoid the quad rail because they tend to be heavier than most other forearms and with today's offerings in the market, unnecessary. You have all the flexibility of the quad rail with out the weight and discomfort to your hand. In many cases, the mounting options are often much better with the modern offerings out there.

Shoot your rifle for a while and see what you like and don't like on it before you go crazy on upgrades. A lot of us have a box or a drawer full of parts we later thought better of or regretted buying.

Of course, the side benefit is that we now have parts for other rifles we buy in the future or have already bought...

 

[Big Shrek]

Who in their right mind would actually hold on to a Quad-Rail as a grip
when you can put an angled fore-grip on the bottom??

On weight, they've still got a company or two that make 'em out of Synthetics

As long as you have a good sling on it, you almost never have to grab the quad-rail
for anything...just the angled grip underneath when getting ready to fire.

 

[cyphertext]

Who in their right mind would actually hold on to a Quad-Rail as a grip
when you can put an angled fore-grip on the bottom??

Who in their right mind would by a fore end that requires them to purchase another part just to be able to grip the rifle for shooting?

Quad rails are great for the military... got to have someplace to hang PEQ boxes, lights, sling attachments, etc... but most civilians only require a light and a sling. There are far better options available than a quad rail.

 

[MichiganScott]

Who in their right mind would by a fore end that requires them to purchase another part just to be able to grip the rifle for shooting?

Quad rails are great for the military... got to have someplace to hang PEQ boxes, lights, sling attachments, etc... but most civilians only require a light and a sling. There are far better options available than a quad rail.

Holding on to a quad rail is like gripping a cheese grater except it abrades your hand instead of making dinner.

Vertical grips on a quad rail allow you to be able to have some sort of grip on the hand guard when it's covered with all the equipment required by the military to be effective. I see no point at all in an angled grip. Maybe that comes from using only a traditional fore end for the last 50+ years and being set in my ways.

 

[C J]

One of my AR's came with a synthetic quad rail. I put a vertical grip on it because just aiming the thing holding that rail was almost impossible. My hand just can't hold one steady. I put an M-LOC on my Sport mainly for the heat shield. Cheap and very effective. I also have a vertical grip on it just because I like them. I did have to reinforce the rail with a bar inside for added strength. I can hold the sight on a target all day that way.

 

[Smith357]

Who in their right mind would actually hold on to a Quad-Rail as a grip
when you can put an angled fore-grip on the bottom??

Me.

I bought a Magpul angled fore-grip to try out on my M&P Tactical and it was on the rifle for all of 4 minutes. I found it very uncomfortable, good thing it was only 10 bucks. I put on soft rubber ladder rail covers and it's good to go.

Edit: That is assuming my mind is right....

 

[Tinhack]

They make pads for the QR. I don't have a problem holding mine.

 

[cyphertext]

They make pads for the QR. I don't have a problem holding mine.

But why buy a quad rail if all you are going to do is buy covers to put over it?

 

[C J]

But why buy a quad rail if all you are going to do is buy covers to put over it?

For all that stuff you intend to add "someday". Like a pop corn popper!

I have the soft covers ove the quad rail I own but it seems like I have to remove way too much to add some item. I put a light on that rifle and I had to remove an entire rail cover. Back to being a pain in the hand. Heck even with the covers I found it uncomfortable.

 

[Muss Muggins]

But why buy a quad rail if all you are going to do is buy covers to put over it?

Mine has soft rubber ladder-looking pieces that fit into the rails and grooves. Can't remember the manufacturer, but they're similar to the plastic pieces that fit the rail of my M&P 15-22 (came with). They're cut to cover the part of the rail not occupied by the foregrip, light, backup sight, optic, etc. Couldn't get those pieces on where I want them with the M-Lock or the Key mod . . .

Edit: They look like this:

 

[cyphertext]

Mine has soft rubber ladder-looking pieces that fit into the rails and grooves. Can't remember the manufacturer, but they're similar to the plastic pieces that fit the rail of my M&P 15-22 (came with). They're cut to cover the part of the rail not occupied by the foregrip, light, backup sight, optic, etc. Couldn't get those pieces on where I want them with the M-Lock or the Key mod . . .

Edit: They look like this:

You couldn't get your accessories where you want them with M-Lock or Keymod, or you couldn't get covers for unused space?

 

[Muss Muggins]

You couldn't get your accessories where you want them with M-Lock or Keymod, or you couldn't get covers for unused space?

Take a look at the difference in spacing on the M-Lock or Keymod holes when compared to a quadrail. Didn't work out for me. (Want to buy a very lightly used M-Lock or a Keymod?) . . .

 

[cyphertext]

Take a look at the difference in spacing on the M-Lock or Keymod holes when compared to a quadrail. Didn't work out for me. (Want to buy a very lightly used M-Lock or a Keymod?) . . .

I can see that... MLOK and Keymod will get the accessories in the same general area, but quadrail allows for a little finer adjustment, especially if you are putting something at the very end of the tube.