AR-MPR 1st Range Report – Unexpected Results

Completed AR-MPR Rifle - Click For Larger View - Image Copyright 2011 Ultimate Reloader


The mission for the first range trip with the AR-MPR rifle was to really do two things: First, it was about function checking the rifle. Second, it was about sighting in the Nikon Monarch 6-24x50mm riflescope. A third and less important goal was to see how accurate I could shoot this rifle based on some quick loads I whipped up with the RCBS Pro-2000.

I was expecting that the Nikon M-223 scope mount might not work with the chosen Nikon Monarch scope because of the mount’s built-in 20MOA downward slope. As expected, the rifle was hitting high at 100 yards (by about 8″) even with the scope elevation cranked down. So, I had to swap out the mount for a J.P. mount (thanks Bruce for the loaner!) with no slope built-in. The rifle was then soon zeroed in at 100 yards.

It was very exciting to pull the trigger for the first time! I was shooting off the harris bipod at 25 yards so that we could start to zero in the scope. As I hoped, the rifle went “BOOM” and I felt for the first time the manageable (but noticeable) recoil, and the “wind in my hair” from the rearward pointed gasses exiting the muzzle brake. “This is simply awesome” I told myself. I looked over to Tim (UR staff) and Brad (friend from the range I just joined) with a large grin on my face. I started with a single round in the magazine, and then had Tim shoot of the next two (hey, better safe than sorry with accidental full-auto fire, right?).

Here’s a shot of the updated scope mount arrangement:


JP Scope Mount and Nikon Monarch Scope in AR-MPR - Image Copyright 2011 Ultimate Reloader


Moving to 100 yards following the scope mount swap-out, my groups started shrinking. Keep in mind, my goal for the day was about 1″ groups (that’s good for a first AR-15 range trip right? No tailored loads, etc). I was then planning to work hard to make the .5-.75 MOA accuracy goal by doing single stage sniper style handloads (trickle powder loads, etc).

Well, the unexpected surprise came in the form of groups (starting here with 3 shot groups) that measured as small as .285″! Wow- I guess AR-15s really can be accurate!

Here’s the best group of the day – 0.284″ 3 Shot Group – On cardboard:


Best Group of the Day - Surpassing the project accuracy goal by ~50% - Image Copyright 2011 Ultimate Reloader


But, that wasn’t a fluke, there were other good groups like this one:


Second best group of the day - Image Copyright 2011 Ultimate Reloader


Don’t worry, we’ll still have Phase II (precision handloads on Redding Big Boss II) and Phase III (ammo mass production on progressives) as a part of this project, we may just have to tighten up the accuracy goal. I can tell you, my thoughts yesterday leaving the range were a huge stamp of “Mission Accomplished!” in my head. Success! Thanks again to Larry Weeks at Brownells and Jon LaCorte at Nikon for their knowledge, experience, and sponsorship! These are really class-act guys (and companies).

What do you all think? What should the goal be for accuracy given this rifle’s ability to perform?

15 thoughts on “AR-MPR 1st Range Report – Unexpected Results”

  1. Hey Gavin,

    How come I didn’t feel the “wind through my hair” on rounds 2 & 3? 🙂

    Thanks for letting me a part of this! Awesome trip and can’t wait to do it again, soon!

  2. Three shot groups are not a statistically significant way of judging group size. 5 shots at least!!

    Congrats though. Love your work.

      1. 10 shot groups each, two by one shooter, two by another, alternating between groups. This will give you a better indication of how well you work with the rifle and the rifle works with the ammo used.

  3. Hey Gavin, love the series so far. Once you have the rifle dialed in, then give us some groups out to 400 yards. Then you can try to build a 22-250 upper, if it’s possible…

    1. Brian- Glad you are liking the series. I’m really enjoying it as well, it kind of makes me wonder why it took me so long to get into the whole “AR thing” (have typically shot bolt rifles for serious shooting).

      At my range, we have 25 yard, 100 yard, and 200 yard ranges. So, near term I’ll shoot it out to 200 yards. But, I’m looking into doing some blogs on loading 50 BMG, so I’ll be headed to longer distance ranges too- that’ll be a good time to try 400+ with the AR-MPR!

  4. Hey Gavin can you tell me where you purchased the ptx linkage for the lock and load powder measure to set your expander depth. Hornady lists it in their 2011 catalog but it doesn’t come up and I haven’t been able to locate it from the other dealers I deal with. Thanks Robert ==

  5. I agree with Michael, 3-shot groups are not a viable way of measuring a rifles true accuracy. I would suggest upping it to 5-shot groups, nice work none the less!

    1. I agree too. This wasn’t really meant as formal testing 🙂

      Consistent .5″ 5 shot groups would be great, and as a stretch, perhaps a 5 shot .25″ goal. There’s a lot of room left for improvements. Fireforming and exact cartridge headspacing, measuring optimized COL, varying bullet weight, using the Hornady Concentricity tool, hand trickling powder. This is going to be fun!

  6. Gavin,

    Some help here. I can’t seem to get better than 2.5 MOA on reloading for 5.56 at 100 yard. I’ve used Varget! BCL2, and IMR 8208XBR; NATO brass, Hornady 55. Vmax.

    Do you think it’s because my 16″ barrel is a 1:7 twist ? Do you turn your necks or use Hornady’s concentricity tool? I use a 4x scope.



    1. Shin- can you give us more details on your rifle? Free-float handguard, fixed handguard? That would be a good starting point. For most AR-15s, 2.5 MOA is not that bad. For a precision AR-15, you can likely do better.

  7. I have a customized S&W M&P 15T with free-float barrel. The load I have been using is:

    Sierra 55 grain Game Kings
    Hodgdon Varget- 26.3 grain +/- .1g
    Federal .223 and Lake City 5.56 brass
    CCI small rifle
    COL= 2.219

  8. Gavin,
    Have you had any experience using Alliant’s ReLoader 10x for loading .223? I hear this is a great powder for that cartridge. Maybe you could do a test of a few of the most popular powders for .223/5.56 and post the results. Also the new Copper Fouling Eraser from Hodgdon.

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