#49881
Sgt. Mike
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The 6mm AR Turbo this is cut and pasted from Robert Whiley’s site

 

 

I have been working on and testing the “6mmAR Turbo” that is a new 6mm AR-15 cartridge, similar to the 6mmAR, but with a greater powder capacity.   For a shooter wanting to shoot plain bullets out of an AR-15, it appears somewhere between 2850 -2900 fps for a bullets in the 105-108 gr range is a realistic upper end number.  With moly bullets, probably a bit more is possible.

The 6mmAR Turbo – easy to make!
The 6mmAR Turbo is easy to make, just take 6.5 Grendel cases, run them through your resize die, load them and shoot them – No neck turning – No Trimming – Not Complicated!

Above – A plain 6.5 Grendel case on the left, then in the center a loaded new resized 6.5 Grendel case (resized at the neck for the 6mmAR Turbo) for fire forming (notice the false shoulder at the neck), and then on the right a finished fire formed and re-loaded 6mmAR Turbo.  Take new 6.5 Grendel cases, run them through your sizing die, load them and shoot them – What could be easier!  (note false shoulder on middle case)

Above = 10 Shot Slow Prone Testing Group
With 6mmAR Turbo

The target above was shot slow prone at 100 yards while doing some basic load work ups for 600 yards.  Since this was initiaI load testing, I decided to start with a loading down around 2830 fps, so the powder measure was set to throw around 29.8 gr of RL 15.  The cases were previously fire formed and re-sized and primed with CCI BR-4 primers.  There were 25 cases, so for group testing 12 were loaded with Berger 105 VLD’s in the lands .010″ and 13 with the Berger 108’s jumping .010″.  The load with 105 VLD’s shot o.k. but still needed work, but the load with the 108’s was a hammer and resulted in the target shown – if I could hold well, the bullets kept going through the same hole.  I would not hesitate to take the load with the Berger 108’s to the 600 yard line right away.  This was shot with a scope in slow prone with a sling and the target is the slow prone target.  The group is a little low, but once I start shooting for group I don’t like to click around.

Below Chrono Tape
For the chrono work, all bullets were plain (no moly) and I pushed it to see where was a realistic upper end – I think about 2900 fps with naked 105 Bergers is about there.  I could probably go to 2950 with plain (non moly) bullets, but I think that would be too hard on the brass.

Below – Additional Testing

The chrono testing below was to see about where the Berger 108’s load was shooting (velocity wise).  This was the load that was used on the 10 shot slow prone target above.  It looks like the 29.8 gr of Reloader 15 load was shooting right near the 2830 fps mark with the Berger 108’s (naked non-moly bullets).  Another 10 shot target was shot slow prone with a sling at 100 yards later with the Berger 108’s (see below).  Considering the wobble zone of shooting with a sling, this 6mmAR Turbo upper shoots the 108’s very well.

6mmAR (Left) vs 6mmAR Turbo (Right)

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