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The Process: Small-Frame AR-10/.308 Testing Day 1

By October 26, 2017Uncategorized

The Process:  Bringing the F4 Defense Small-Frame AR-10/.308 to Market – Day 2

F4-X Small-Frame .308

Testing Begins……Again

The magazine catch fix worked fine in the shop and held magazines firmly, so we headed to the range to do some testing.  Zero issues, running both lowers.  Magazines held as they should so we’re are past that issue.  With the mag catch in the rear view mirror it was time to put some rounds downrange.

I setup at 100 yards and just started feeding this thing ammo.  Everything from cheap Federal 149 grain to the better quality shelf ammo, Federal Gold at 175 grains.  To say we were pleased with performance on the first day out would be an understatement.  Because we were running reliably with a wide range of ammo we decided to throw a suppressor on there and shoot a few rounds through an Osprey from SilencerCo.  Running suppressed didn’t change our point of impact and it ran pretty damn well VIDEO.  We had a double feed and a few times the bolt failed to hold open on the last round.  The only issue I would label as a concern would be the cratering we saw on the primer.

Firing Pins

We use the DPMS Gen II Bolt Carrier Group along with some of the other parts that allow us to make a Gen II Compatible weapon system.  After a discussion with our engineer and a senior engineer with Remington/DPMS, it turns out that we had the older BCG design.  The older design had a larger firing pin diameter at the tip (0.075) and opening on the bolt face. The new design was reduced to (0.065) and I’m sure that will take care of the cratering on the primer.  We’ll test it in the next few days and see what happens.  Extraction was good, if a bit hard from having two (2) ejectors on the bolt.  This was the first experience I’ve had with dual ejectors, but no issues noted and the brass was ejecting consistently.

At F4 we pride ourselves on building sub-moa weapons and we aren’t going to accept anything less with fielding a new platform.  Here are the results from our limited accuracy testing.

  • Hornady Superformance .308 GMX, 150 grain: 5-shot group at 0.915 MOA
  • American Eagle 7.62x51mm, 149 grain: 5-shot group at 1.192 MOA
  • Federal Gold .308, 175 grain: 10-shot group at 0.783 MOA

The Federal Gold performed very well in our Black Hole Weaponry Barrel.  Here are the specs on our barrels.

  • Length: 18”
  • Gas System: Mid-Length
  • Twist Rate: 1 x 9.76
  • Rifling: 3 Land Polygonal
  • Profile: Standard/Light

BHW makes these barrels exclusively for F4 and they are DPMS Gen II compatible.

In closing, I just want to touch on a few observations.  The recoil was relatively light, especially considering this Small-Frame .308 is less than 8lbs.  It was comfortable to shoot.  Over the next few weeks we will start to tweak our gas settings and buffer system to improve the platform.  We also want to explore going with a rifle length gas system.  Once we work out a few kinks, we have 12 rifles going to testers across the country so we can do a proper T&E of these F4-X Small-Frame .308’s.

We are keeping a handful of rifles to continue our own testing and do a side x side comparison of two barrels.  Our Black Hole Weaponry barrels and the DPMS Gen II compatible barrels by Rainier Arms.  The guys over at Rainier wanted us to evaluate their barrel and possibly field them with our rifles.  I know quite a few of you would be interested in seeing how they perform so we’ll do some testing and post updates in this blog series.

As we get closer to release, we are going to start exploring the other calibers we plan to carry, which are:  6.5 Creedmoor, .260 Remington, .243 Rem and/or .264 LBC.

Standby for updates and please ask questions and post comments, I would love to hear from you guys as we go through this process.  Thanks for checking in!


Dave Fairfax, F4 COO

One Comment

  • Mitchell Cooper says:

    I’m in the market for an AR10 platform rifle chambered in 308… but after hearing F4 was in the process of making one, and reading that tests are exceeeding expectations, I think I will hold off on my purchase. Please keep the updates coming, I’m following intently.

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