Reloading The 80grSMK For Your AR15: 200Yard Testing

| August 23, 2015 | 1 Comments

With a box of 80grain Sierra Match Kings in hand I decided it was time to head to my reloading bench and prepare a few rounds for testing at 200 yards on the range.

DSC02348The 223 Remington is one of the most popular cartridges in the world. It has the capability to fire bullets from 35grain to 90grain all dependent upon the rate of twist of your barrel. To fire these 80grain bullets you do need to adhere to the warning in the reloading manuals and on the box. 7″-8″ twist barrels are required and they are single shot only. The COAL required will prohibit these rounds from fitting inside of a magazine. All though the 77grainers can be loaded to magazine length, according to Sierra these can’t and will only increase pressure in doing so and most likely will cause damage to your rifle and bodily injury.

DSC02347Before deciding upon an overall length I used my Hornady Overall Length Guage to determine the proper COAL. In my AR15 a COAL of 2.455 was good enough to allow for a bullet jump of .15 this would also allow for proper cycling.

Testing:

To conduct this test I would use LC Brass, Federal Gold Medal Match Small Rifle Primers, 24grains of Reloader15 Powder. Please verify your loads in a proper reloading manual for the components you plan to use. For consistency I verified all charges thrown by my RCBS chargemaster on a RCBS 5-0-5 balance beam scale, I was pleased to see all were spot on. All brass was trimmed to 1.750, chamfered and deburred and primer pockets uniformed on my CTS case prep center.

Also part of our testing is something I have been very curious about, crimp vs no crimp and the effects on accuracy. I would load 10 rounds crimped and 19 rounds non crimped. They would be fired in two different rifles, one 20inches long with a 8″ twist and the other 24inches long with a 7″ twist.

The first group is the lightly crimped loads at 200 yards.

The next targets are groups of the non crimped loads at 200 yards.

DM had a much tighter group, but I would squeeze out a better score with rounds much closer to the bullseye.

For our last rounds of the day, we decided to make scope adjustments doing our best to read the wind. DM would fire 4 rounds and I would finish out the day with 5 rounds of non crimped loads.

Upon firing his last and final group of the day DM realized he had gone to far on the windage adjustment. I to would make a slight windage adjustment but would use the BDC Reticle of the Nikon M-223 to correct for my elevation.

All loads for the day would fire without failure or showing signs of excessive pressure.

With a little more practice I know we can tighten these groups up as we have shot 308W at this distance and groups were well under 1/2 MOA for both of us.

Needless to say I will be loading the 80grSMK without crimp, I am well aware it is good practice to load with a crimp for semi-auto rifles to avoid bullet set back. But I ensure all of my non crimped rounds have good neck tension by the case.

 

Though a short range trip it was another great day on the range.

Stay tuned, the next trip may just be a ladder test of loads shooting them across the chronograph to find the most accurate load.

Fun, Fun, Fun

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1 Comment on "Reloading The 80grSMK For Your AR15: 200Yard Testing"

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  1. Bill U says:

    I have an unopened box of 500 of the 80 grain Sierras. You have inspired me to load some up! Excellent article.

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