Smith M&P10 final config. and accuracy testing

ASH556

Senior Member
I picked up this Smith & Wesson M&P10 a week ago and have been putting it together Cash style (1 pc at a time) as the parts arrive. As of this writing, I am waiting for the final piece, which is an IWC QD sling point to attach in the handguard instead of the rail piece/sling QD combo thingy that MI includes with the handguard. Let's start with a rundown of the gear:

Rifle: Smith & Wesson M&P10, .308 Win., 18" 5R lightweight barrel
Handguard: MI 308 SS freefloat tube handguard, modified with screws drilled and tapped through the handguard and into the barrel nut for better security.
Charging Handle: Factory (it's proprietary) with Badger Gen 2 Latch
Gas Block: MI Low Profile 0.75" Gas Block
Brake: JP Enterprises "Tactical Compensator" 2.25 x 1
Sights: KAC 99051 folding front, Matech folding rear
Light/mount: Gear Sector 6P mount, Surefire G2X
Optics: Trijicon TA11HG ACOG in Larue mount
Buttstock: B5 Gen 1 Sopmod w/Gear Sector QD sling attachment
Grip: BCM Gunfighter Mod1
Trigger: Geissele SSA-E

**One modification I want to be sure and mention is the replacement of the ejection port cover rod. Some may not know that there are two lengths of this rod. The standard AR10 rod and the AR10T rod, which is 1/8" longer. When changing from the delta ring assembly to a freefloat handguard, you need the longer AR10T rod. Otherwise, the standard rod will walk forward under recoil and out of its recess in the receiver under the deflector. I got mine directly from Armalite.

The idea behind this configuration is to be a general purpose outside rifle for hunting deer and other large game in the Southeast US as well as being available to provide fast and accurate fire if needed from 50-800 yds. Some of the options above are self-explanatory. I chose the compensator because the factory muzzle device is like 3.5" long, and not terribly effective. I figured at .308 is loud anyway, I may as well gain the advantage of faster follow-up shots and being able to spot my own shots. The JP Brake accomplishes this. The ACOG is the fall-out of a very long journey I made through most of the popular Low-medium powered AR optics. There's a thread on here you can search for and read if you want to know more about that. I don't want this to be a precision rifle necessarily, but I do want some magnification and the ability to compensate for bullet drop at ranges. The ACOG does that, all while being rugged, lightweight, compact, having bright and clear glass, and an illuminated reticle.

Now, before getting into this rifle, I read as much as I could online about it and honestly was disappointed at how little good info there was about it. Hence, my hope in starting this thread is that info is shared and those interested can ask questions and gain insight into a future purchase. I had read about this rifle being "MOA accurate." Well, without pics to prove it, we all know that MOA gets stretched a lot. So, I went and bought a box of Federal Gold Medal 168gr .308 from the local gun shop and mounted a Zeiss 3-9x40 (the highest magnification scope I own) scope on the rifle to give it the best chance to show what it could do. The procedure was to setup a target at 100yds. I planned to fire 4 consecutive 5-shot groups at 100yds to capture the effects of the barrel heating, etc. First, though, I had to confirm that the scope was going to hit what I was aiming at, so I fired 7 rounds of PMC 147gr at a 2" aiming dot below the actual target to confirm that the scope was close. So, technically, I suppose I began the test with a somewhat "hot" barrel and got it hotter as the test went on.

I loaded a 20 round PMAG with the 20 rounds of Federal 168gr and got prone in the bed of my truck with the forend resting on my hunting pack. The rear of the stock was supported by a sandbag. I will post the pictures of the groups below in chronological firing order (first through fourth). I made a slight windage adjustment after firing the first group, and you'll note it below. I fired at a rate of roughly 1 round every 3-4 seconds. I do wish I had a higher power scope for the accuracy test, though. While the Zeiss is a wonderfully clear hunting scope, the crosshairs are a bit thick and 9X is a little shy, so I couldn't really see where on the red dot I was aiming because the crosshairs covered the whole thing. Even so, I think the rifle did well. The Good Lord saw fit to bless us with rain yesterday, so I got to fire the groups in a steady drizzle. So here are the groups:


M&P10 grp 1 by ASH556, on Flickr

M&P10 grp 2 by ASH556, on Flickr

M&P10 grp 3 by ASH556, on Flickr

M&P10 grp 4 by ASH556, on Flickr

Untitled by ASH556, on Flickr

Untitled by ASH556, on Flickr

I find it interesting to note that the last group fired was the best because at that point the barrel was good and hot. I think I had probably just settled into the best position and firing rhythm. It does speak very well of the barrel, though, that even with heat the POI doesn't shift and the shots aren't stringing. When I was looking at getting this rifle, I laid out a 1.5-2MOA accuracy criteria. This rifle beats that easily. Now, with the ACOG, based on some shots I fired while zeroing it with my Federal 150gr Fusion hunting load, 2" is the best I could do, so my hunting combo (rifle, optic, ammo) is a 2MOA combo. Still works for me!

As of yesterday, I have fired 73 rounds through the rifle. I have had two malfunctions. Both were with 147gr PMC, which I suspect is loaded to Nato pressure (box is labeled 7.62x51). The first was a failure to lock back on an empty magazine and the second was a failure to feed where the spent round was fired and ejected, but the bolt partially closed on the round, about halfway up the brass with the primer end of the round still down in the magazine. Both of these were after I had fired the 20 rounds of match ammo and so the rifle was dirty. The combination of a dirty chamber, rain, lack of lube (I initially lubed the rifle with Slip 2000 a week prior to this range session when I first got it and had not added any since), and low-powered ammo are to blame for the 2 issues...not the rifle.

Overall the rifle feels to me about like an 18" AR15. It's really trim and pretty lightweight. Completely different from handling an LMT or a KAC, which could not be mistaken for an AR15. Also, there's no denying that the price point of the M&P10 makes it attractive.

Here are a few pics of the rifle in its final configuration. You'll note the ARD removed from the ACOG in some of the pics...that stupid thing is now a permanent resident of my workbench. The little honeycombs hold water like you wouldn't believe and I very quickly couldn't see through the optic anymore....remove the ARD, problem solved. To me, that's a critical issue and since I'm much more likely to encounter rain than a countersniper who sees the glare off my objective lens...the ARD stays off.


Untitled by ASH556, on Flickr

Untitled by ASH556, on Flickr

Untitled by ASH556, on Flickr

Untitled by ASH556, on Flickr
 

pnome

Senior Member
Nice write up and awesome rifle!


Bet it would look better with a wood stock though. ;) ::ke:
 

ASH556

Senior Member

thc_clubPres

Senior Member
dang, you took your new rifle in the pouring rain. I wouldn't even bring mine out if it was overcast till I had it a few months.

Looks good tho. accurate
 

DYI hunting

Senior Member
Great write up! Looks great with the ACOG. I may trade off my Leupold Mark AR Mod 1 for a lower power 1-4x which I think is more suited for this rifle at least for me.

Tell me more about drilling and tapping the handguard? How deep did you go? Did you do it to prevent the handguard from twisting or flexing enough to touch the barrel? I might need to look into that for my Troy since it does sag a little on the bipod and gets close to touching the barrel.

Also how much difference in recoil did the Tac Comp make?
 

ASH556

Senior Member
Thanks, and sorry for the short reply...on my phone. The drilling/tapping of the barrel nut was to prevent this from happening:
8EA039DF-CABF-4A20-A745-71BC13103C4B-353-0000002D01DE309A_zpsee4671a6.jpg


A guy was shooting that in the range where I work part time and as he said, "the front fell off." The MI handguard has anti-rotational tabs that engage the barrel nut and keep it from rotating but only the clamp force of the two screws around the front keeps the handguard from shifting forward under recoil. I installed the screws to prevent this. I drilled all the way through the barrel nut but the screws are short enough that they don't go beyond the inner diameter of the barrel nut.

What gas block did you use? Curious about the clearance/bipod issue and if maybe some material could be taken off the block?

The JP brake/comp does a very good job of keeping the rifle flat, which was what I wanted. Inside an indoor range, blast and noise were the same as my 10.3" 5.56 with Blackout Flashhider. I was easily able to spot shots and watch bullet impact at 100yd with the JP brake. It's also a full inch or more shorter than the factory doohicky!
 

DYI hunting

Senior Member
What gas block did you use? Curious about the clearance/bipod issue and if maybe some material could be taken off the block?

I used a Troy Low Profile gas block with bottom set screws. It clears the rail itself fine but if you install a rail section below the gas block it gets a little tight. The rail section is attached with a 1/8" bar that goes inside the rail. I don't think it touches but it gets closer than I like. I used some nuts instead of the mounting bar but I would rather use the bar. The Troy rail in installed at the 1 o'clock position and locks into place (forward/backward movement) when rotated to the 12 o'clock. There are two screws that clamp the rail down on the barrel nut to keep it from rotating or flexing. I wish there was a rock solid rail option like the Midwest Industries 2-piece Gen2 rail I have on my SBR.

Which JP Enterprises Comp did you use? There are several diameters on midway and I can't decide if I need 0.875" or 0.925" to blend into the barrel width. I was happy with the flashhider but I think I'll give a comp a try.
 

EGlock86

Senior Member
Buddy of mine has a 2000 ac. Farm with some long bean fields and that thing would be a critter getter on some hogs down there. I don't know what half the stuff you mentioned is but man I like that gun.
 

ASH556

Senior Member
I used a Troy Low Profile gas block with bottom set screws. It clears the rail itself fine but if you install a rail section below the gas block it gets a little tight. The rail section is attached with a 1/8" bar that goes inside the rail. I don't think it touches but it gets closer than I like. I used some nuts instead of the mounting bar but I would rather use the bar. The Troy rail in installed at the 1 o'clock position and locks into place (forward/backward movement) when rotated to the 12 o'clock. There are two screws that clamp the rail down on the barrel nut to keep it from rotating or flexing. I wish there was a rock solid rail option like the Midwest Industries 2-piece Gen2 rail I have on my SBR.

Which JP Enterprises Comp did you use? There are several diameters on midway and I can't decide if I need 0.875" or 0.925" to blend into the barrel width. I was happy with the flashhider but I think I'll give a comp a try.

You actually need 0.750 to blend in with the shoulder on the end of the barrel. I don't see it on Midway, but Brownells has it (that's where I got mine):

JPTRE-324 - JP Tactical Compensator,5/8-24 TPI, .750 Outside diameter, .350 exit. Carbon steel matte black, SOF/Tactical/USPSA Limited legal.
http://www.brownells.com/rifle-parts/barrel-parts/compensators/tactical-compensators-prod32316.aspx

The Troy MRF has a 2-pc clamp design similar to the MI you have on your SBR: http://www.midwayusa.com/product/30...d-dpms-lr-308-with-low-profile-upper-receiver

It only comes in 13.8", though, and that'll make the gun a lot heavier than the tube you have now.
 

PappyHoel

Senior Member
Me likey...
 

wareagle700

Senior Member
Good write up ASH. This definately looks like the best bang for your buck under 2K. I still need to get out and thoroughly test my .308AR but probably won't be until after deer season.
 

DYI hunting

Senior Member
You actually need 0.750 to blend in with the shoulder on the end of the barrel. I don't see it on Midway, but Brownells has it (that's where I got mine):

JPTRE-324 - JP Tactical Compensator,5/8-24 TPI, .750 Outside diameter, .350 exit. Carbon steel matte black, SOF/Tactical/USPSA Limited legal.
http://www.brownells.com/rifle-parts/barrel-parts/compensators/tactical-compensators-prod32316.aspx

The Troy MRF has a 2-pc clamp design similar to the MI you have on your SBR: http://www.midwayusa.com/product/30...d-dpms-lr-308-with-low-profile-upper-receiver

It only comes in 13.8", though, and that'll make the gun a lot heavier than the tube you have now.

Putting that heavy of a rail on the rifle defeats my intended purpose of a lighter weight hunting/defensive rifle. I think I just didn't have the Troy rail I have now tight enough. I put it back on after cleaning the rifle and tightened it up a little more and it seems rock solid now.

I'll have to look into the brake after Christmas, I spent my gun play money on some upgrades for my Ar-15. I have a single-chamber AAC brake in route for my 300 blk I might try just to see what it'll do on the .308.
 

ASH556

Senior Member
Putting that heavy of a rail on the rifle defeats my intended purpose of a lighter weight hunting/defensive rifle. I think I just didn't have the Troy rail I have now tight enough. I put it back on after cleaning the rifle and tightened it up a little more and it seems rock solid now.

I'll have to look into the brake after Christmas, I spent my gun play money on some upgrades for my Ar-15. I have a single-chamber AAC brake in route for my 300 blk I might try just to see what it'll do on the .308.

Cool, glad to hear you got your handguard sorted. I'd be interested to hear how that "Hollister" Brake works on your .308.
 

DYI hunting

Senior Member
Cool, glad to hear you got your handguard sorted. I'd be interested to hear how that "Hollister" Brake works on your .308.

I only went with the short single chamber AAC so I could get my SBR around 22". I don't think it will do very well on the .308 since it's only 1.375" long and a single chamber. The multiple chamber AAC might do better but probably won't out preform the JP Enterprises
 

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ASH556

Senior Member
I only went with the short single chamber AAC so I could get my SBR around 22". I don't think it will do very well on the .308 since it's only 1.375" long and a single chamber. The multiple chamber AAC might do better but probably won't out preform the JP Enterprises

22"?!?!? Jeez, that's short. What barrel length? My 10.3 is 29" with a Blackout, which I realize is kindof a long flashhider, but even so, take an inch off for the flashhider/brake difference and mine's still 6" longer than yours.:biggrin2:
 

DYI hunting

Senior Member
22"?!?!? Jeez, that's short. What barrel length? My 10.3 is 29" with a Blackout, which I realize is kindof a long flashhider, but even so, take an inch off for the flashhider/brake difference and mine's still 6" longer than yours.:biggrin2:


22" is what I was originally aiming for but the parts are on order so I don't yet know what the final length will be. The final outcome could be as long as 23" or 23.5". I am using a 8.5" 300 blackout barrel and ultra compact stock which is on order.
 
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