I’ve done a few Special Purpose Rifle (SPR) builds over the years and was always happy with the results. After a hard weekend at the range running some difficult drills with an 18 pound 300 Win Mag, I decided to look into configuring a 16″ carbine with an 2.5-10 optic for semi-precision shooting within 500 yards.
While most of the AR-15/M16 M4s you’ll see configured as SPRs have 18″ and 20″ barrels (with good reason), I felt the 16″ barrel and carbine length gas system would make for a handy little package, especially for shooting from improvised positions. Rather than ordering a match barrel and a bunch of new parts, I went through my current collection of parts to configure the rifle shown here.
While I know I can get a match grade heavy barrel to shoot well, the question is how well does a standard, mil-spec barrel, like this one from Daniel Defense shoot?
All of the upper receiver parts were originally ordered from Brownells:
- Daniel Defense stripped URG 16″ 1:7 upper
- Daniel Defense Lite Rail
- Daniel Defense bolt carrier group
I assembled them on a Bushmaster lower, with a VLTOR extension, Magpul CTR stock and a Wilson Mil Spec trigger.
A Nightforce compact 2.5-10x42mm Mil/Mil scope in an ADM RECON mount finished off the rifle with a heavy duty Atlas bipod providing a solid shooting platform.
I ended up with a nifty little rifle- now I just had to make sure it shoots. My goal was to end up with a 1 minute of angle (MOA) carbine- again, it’s not quite an SPR (at the end of the day, I guess it is an M4 with a scope).
In addition to factory ammunition, I made some hand loads. I really wanted this rifle to shoot an established load well, so I brought along my old High Power rifle load, a 69 Seirra MatchKing (SMK) over Reloader 15. Additionally, I worked up some 77 SMK loads on new Winchester brass.
All shooting was done prone, from a bipod with a rear bag. Range conditions were 90F, with the sun at 2 o’clock to the firing line. The targets were a series of 2″ orange dots at 100 yards. Velocity information was recorded with a MagnetoSpeed barrel mounted ballistic chronograph.
Results can be viewed in the table below.
The test target with 2″ orange dots is shown below. The bottom right group is a series of sighters from a different rifle. Most of the groups shown in the table above were fired on this target.
In the past, I’ve had some shockingly bad groups with M855, so I wasn’t that surprised with how bad it shot and attribute its performace to the cartridge, not the rifle (center left in photo above).
I had some high hopes for the 77 grain Sierra MatchKing. A staple of high power rifle shooters for years, I loaded mine on virgin Winchester brass and Reloader 15 powder. Overall, it seems to be a sub 2 MOA load. I did load these cartridges on a progressive press with dropped powder charges and didn’t do any prep on the cases, I think better brass prep would tighten those groups up a bit.
The 69 grain Seirra MatchKing shot well. This was loaded on Winchester M855 once fired brass that had been full length sized and trimmed. The flash holes had be reamed and the primer pocket swaged. The best group was just under .75 MOA. This is the load I will be using in the rifle.
Factory Winchester 62 grain OTM performed well. I’ve been shooting this load for years and this is as good as it have ever shot. Even in a match bolt gun, it doesn’t shoot much better than 1.5 MOA.
The IMI M193 was a pleasant surprise. I’ve had some great shooting M193 over the years, and this load certainly made me feel good about the barrel.
Considering this is a standard weight barrel that has been hammer forged and chrome lined, I am happy with the results. It isn’t the most accurate AR I’ve ever owned, and it isn’t a half MOA rifle, however, with the right load, it will certainly get the job done.
Running the 69 SMK load through my ballistic computer, it looks like the rifle will fill the role I have envisioned for it.
Once I load up some more ammo and shoot it at longer ranges I’ll report back.
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