Ok, so the price was more than right and I decided to put this on an SBR project that was waiting for a suppressor to show up.

I've never owned a piston system before so I really had no expectation other than I knew I could at least break even if I sold it.

The only thing I added was a H2 FSR buffer and spring.

The upper is a 5.56 1-7 twist

Yesterday I ran 50 rounds of 55 gr .223 reloads through it and had really good results (2 failure to feeds and 3 stove pipes though...more on that later)

The fit and finish of the upper is perfect.  The M4 feed ramps were correct the carrier group us well constructed and had good fit.  The Daniel Defense rail is a nice, albeit small rail.  

I had a few expectations before I shot it:

1.  It was going to heat up like a bitch on the gas block and barrel - NOT TRUE.  Under rapid fire 20 round groups, it really didn't heat up bad and cooled quickly.

2.   The muzzle flash was going to be HUGE. - Again, NOT TRUE.  It had flash but I wasn't affected by it while looking through the Aimpoint

3.  Muzzle blast - TRUE  It did put out some blast.  Enough to move the cords from the target retriever (4 feet above me) and cause the target to shake

4.  Uncontrollable - NOT TRUE.  This was the most surprising part.  This is a pleasure to shoot.  I am easily able to keep 20 round rapid fire 8" groups @ 35m offhand.  I only plan to set this up for for 50m.  

I will keep this upper and all I need to do now is figure out the few failure to feeds and stove pipes (SUGGESTIONS ON THIS???).  Does anybody have AA problems with this

I was running a 20 round PMAG.  I don't know if it was the ammo, mags, buffer spring, loose hold...? (I didn't test another mag or ammo as I didn't bring any)  

The issues seemed to occur 5 rounds into a rapid fire.  The stove pipes required a tilt to the right and charging handle pull.  The failure to feed required another charging handle pull.  On the last round the bolt would sometimes not catch.  It would immediately catch upon re-charge.

http://i537.photobucket.com/albums/ff339/000002s/SBR/SBR.jpg

http://i537.photobucket.com/albums/ff339/000002s/SBR/SBRSide2.jpg

http://i537.photobucket.com/albums/ff339/000002s/SBR/SBRSide1.jpg

http://i537.photobucket.com/albums/ff339/000002s/SBR/SBRFront.jpg

http://i537.photobucket.com/albums/ff339/000002s/SBR/SBRSide3.jpg


First 5 rounds through the rifle (Ok, it doesn't mean much....but I was surprised at the group considering I was firing to fire)

http://i537.photobucket.com/albums/ff339/000002s/a3abb1b6.jpg

20 rounds, rapid fire, @ 30m, off hand (small pistol silhouette targets)

http://i537.photobucket.com/albums/ff339/000002s/71911e74.jpg

1. That rifle is pure sex



2. Great review. Will you say how much you have into it?

$1018 complete rifle
$359 optics
$200 tax stamp

Nice rig. You try other mags when it hung up? Last round hold open makes me think that's the problem. What ammo you shooting?

20 round PMAGs and .223 55 gr.

You try more than one though?

 "Yesterday I ran 50 rounds of 55 gr .223 reloads through it and had really good results (2 failure to feeds and 3 stove pipes though..
  .more on that later)  "

  Don't  change anything until you test with some Lake City or equivalent.

  And yes that's a seriously HOT SBR.  

The reloads were lake city.....LOL

It could be a short stroke problem.

^  YUP


Well, range day 2

This time I brought 3 different types of ammo and 5 different types of magazines.

I also changed out the extractor spring/o ring.

The only issue left is an occasional failure to feed.  I also had 3 issues with the bolt not staying open on the last round (funny though only slow fire).  BUT....it always hung about 2/3 open on the follower on my better mags with newer springs.

I am now 100% POSITIVE it's a short stroking issue.  I am going to take 2 coils off the buffer spring and this should do it.

This time I put 20 rounds out in under 1 minute a few times in a row.  I did start to get heat off the front sight, gas block and lower part of the rail.  The birdcage and front of the barrel were also hot.  Hot enough to burn but not glowing hot.  It cooled down quickly and the front rail handle kept any heat off my hands.

Again, I would recommend this set up (once you get it working right) for the right applications.  The iron sights are about useless for more than minute of pie plate @ 30+ meters offhand.  With the CompM2 it's will hold 2" 5 shot rapid fire groups off hand and consistent 1" 2 round groups offhand.  It is amazingly accurate at 15-50m offhand.  I would have 100% confidence in it's ability to put rounds where I pointed it.  All three ammo types pretty much hit at the same point of aim and grouped well.

I'm not sure what it will do at 100m-200m from a bench, but this isn't every going to be a distance weapon.

I am tempted to switch sight to the 1.5x16 Trijicon.


We'll see, first the coils and 100% functioning.