20 Practical AR Uppers Deliver Great Accuracy
In 2008, as a “proof-of-concept”, AccurateShooter.com created a 20 Practical AR15 “Ultimate Varminter” with a custom 20-caliber upper from Robert Whitley. That project rifle was ultra-accurate — every 5-shot group out of the gun was less than the size of a dime. That gun was auctioned off, but Robert Whitley (AR-X Enterprises, LLC) continues to produce custom 20 Practical AR15 uppers. (The 20 Practical cartridge is simply the .223 Rem necked down to 20 caliber — you can use standard .223 brass and load with standard.223 Rem dies. Just swap in a smaller expander and use smaller neck bushings.)
Robert reports that the accuracy of the first 20 Practical AR15 was no fluke. After buildign six (6) more 20 Practical uppers, he tested them for accuracy and they all shot great. These uppers feature DPMS low-pro receivers with side charging handles. They are fitted with PacNor 1:11″ twist, three-groove stainless barrels.
Robert reports: “We have been making more 20 Practical AR15 uppers and I have to say I am astounded by the accuracy of these things. For shooting little tiny groups out of an AR15 with bullets going 3500+ fps, it’s hard to beat the 20 Practical. Today I test-fired six more uppers, all with 11-twist barrels. Three of the uppers had 24″ barrels, two had 20″ barrels, and one had an 18″ barrel (we call it ‘Stubby’).
In four of these uppers I shot re-sized Winchester brass using 25.3 grains of WC844 powder with Berger 40gr BTHP bullets loaded at 2.225″ OAL (about .015″ off the lands). WC844 is inexpensive military surplus powder that is nearly identical to H335. I tried three different primers and the choice did not seem to matter (CCI BR4, Rem 7 1/2s and Win Small Rifle — the old silver ones). All these four uppers shot great. Here is an overlay with targets from uppers #6, 10, and 11. All groups are mag-fed, 5-shot groups shot at 100 yards using a front rest and rear bag.”
Neck Tension is Important
With four of the uppers, Robert used Winchester brass which had good neck tension, and accuracy was excellent, as shown above. However, for two of the uppers (uppers #3 and #5) Robert used some old 20 Practical ammo that he pulled down and reloaded without re-sizing the case neck. Robert says: “With this old ammo, the neck tension was way too light and the accuracy was so-so, i.e. between .75″-1.0″ at 100 yards — which for a lot of ARs is still considered ‘very good’.” Lesson learned — accuracy may suffer with the 20 Practical if your neck tension is inadequate.
For more information visit www.6mmAR.com, or contact Robert Whitley via email: rcw3 [at] erols.com.
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Tags: 20 Practical, 20 Tactical, 20-223, AR15, Upper
