So I'm new to the ar platform, well except for my m&p15-22. I just recently bought an m&p 15 sport model. I'm wanting to change out the hand guard for a free float quad rail. Problem is I don't know where to begin, I know I need a low profile has block because of the a2 style front sight/gas block. Any suggestions would be greatly appreciated. Thanks

Some things are an easy to change out item, usually referred to "drop in"replacements/upgrades. Going to a free float quad rail from standard handguard including changing gas block is not one of those upgrades. You're going to need some specialty tools. The good forum members here can walk you through it, but a tutorial found on YouTube might be better. I'd start with watching it done in YouTube and make sure you are up to the task before ordering any parts or tools. You might want to dive in, or you may want help from a friend or gun smith.

Good luck, and happy shooting!

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686/M&P9 Pro/M&P15X/M&P15-22

Good advice from Vinney.

Although, I would ask you a more fundamental question - Why do you feel that you have to change to a free float?

Youtube is your friend. How to install a free float handguard:

Brownells - Installing A Free Float Handguard - YouTube

You'll need a few tools. I may miss a few.

1. Vise
2. AR-15 upper vise block
3. AR-15 Bench Block
4. AR-15 Armorer's Tool
5. Beam type torque wrench
6. Flat head pin punch
7. Roll Pin Starter punch
8. Delta Ring Compression Tool (Not essential but makes removing the old handguards easier)
9. Ball Peen Hammer
10. Penetrating oil

Keep in mind that the S&W A2-F front sight gas block assembly uses tapered pins, and they are driven out opposite from every other manufacturer. I can't remember... right to left? Someone here will remember and chime in.

I advise spraying the tapered roll pins with a little penetrating oil. You're going to have to use very stout hammer blows to drive the pin out.

Quick and dirty steps...after removing the stock handguards....

1. Install upper into vise block
2. Install into vise.
3. Use the armorer tool to remove the flash suppressor.
4. Be sure to save the crush washer.
5. Remove upper from vise.
6. Put front sight gas block into bench block.
7. Hammer out tapered pins.
8. Slide off FSB/Gas block off barrel. Set aside. Make sure not to bend or kink the gas tube.
9. Put upper back into vise block, back into vise.
10. Remove the barrel nut using the AR-15 armorer's tool.
11. Remove the Delta Ring
12. Remove barrel.
13. Go back to the FSB/Gasblock.
14. Tap out the small roll pin that affixes the gas tube to the FSB/Gas Block.
15. Remove Gas Tube and set aside.

Once you got it all apart, check the instructions that comes with whatever free float system you choose. Some free float handguards use proprietary barrel nuts. Some utilize the stock barrel nut.

When reinstalling the barrel. Set the torque wrench to 35 lbs. Torque until the wrench reads 35 ft/lbs, loosen, torque to 35, loosen, torque to 35. You'll then have to time the barrel nut so that the gas tube can pass through. Do not exceed 80 ft/lbs.

YHM makes a clamp style low profile gas block. I have one installed on my 15-Sport. 15-Sports accept most everything out there. I know...



I have to throw out the standard....

Go to the range and shoot the snot out of your 15-Sport as it is out of the box. Get some trigger time to identify needs from wants. You'll then know what you need to swap out, and what may feel good to you. Spend $$$ on a case of Wolf Gold ammo.

Maybe you'll figure out that you won't be shooting longer distances to necessitate a free float handguard. You'll be able to spend the $$$ on a good optic, trigger, stock, grip, etc...

Good luck and safe shooting.

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-John

Oh one more tip...

I have a Troy Alpha rail. Now those are "old" tech.

Standard Handguard > Quad Rail > Free Float Quad Rail > Alpha Rail > Keymod

If you're going to drop the coin on a free float hand guard, be sure to check out the Keymod rails. They have a narrower diameter and they're lighter. The Keymod system makes them super easy to mount accessories.

The Alpha rail is nice, but compared to a Keymod it's heavy and hard to affix accessories to.

__________________
-John

AND...

If you're not going to run optics only, you'll need a good set of folding iron sights. Don't cheap out on sights. I recommend Troy battle sights. Magpul makes a set of metal backup sights.

You can also affix a nice set of 45-degree offset sights.

__________________
-John

Welcome to the modding black hole.

__________________
-John

Welcome! JaPes has pretty much summed it up, so I'll tell you welcome again and post up a few pictures. Careful around here, it become contagious.

Starts like this



Becomes this



Ends up like this



Good Luck and good shooting.

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SFC, US Army, Retired

Thanks for all the information, I think I can handle it from here, this weekend I plan on running a 500 round box through it while it's still stock. Also I am thinking about just getting a basic drop in rail until o can find the free float I really want, but once again thank s fir the information