Load for AR .223

S

Stats Shooter

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I finished development of a hog AR load... could be used on deer too.

Gun: Ruger SR 5.56 Varmint, 20" stainless steel bull barrel 1:8 twist.
Scope: Leupold VX-R 6x18x40

Bullet: 62 grain Federal fusion
Case: .223 rem (Remington brand headstamp)
Cases trimmed to minimum
CCI-450 primers
Seated to 2.250 COAL (easily fits magazine)
Powder: CFE 223 - 26.4 grains
Best group - 0.26".....worst group 0.88", avg 0.56"
Velocity 3155 fps, SD 21 fps

Notes: -VERY light crimp (bullet has cannalure).
Accuracy nodes at 24.9/25.0 graines AND 26.4/26.5 graines. Groups at 24.9 grains average about 1/8" wider than 26.4/5 grains but that could have just been me and the breeze.

Primers beginning to flatten at 26.5 grains, 3 0'clock ejection.
Primers flat at 26.8 grains w/ groups opening up to 1.1 MOA average..... testing discontinued as it was unlikely I would find another accuracy node before over pressure.

An aside- this bullet had no load data, however hodgdon says max charge for another 62 grain bullet is 27 grains of CFE .223.

Also, air temp when testing was 65 degrees and CFE 223 does react to temperature, so the flat primers at 26.7 grains could be pierced primers in 90+ degree weather.
 
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Sounds like it's shooting well.

Note that the 27 grain maximum is for a Barnes bullet. Those are copper solids that produce higher start pressures than cup and core construction does. This is partly due to the hardness of the copper and partly to the lower density of copper causing copper solids to be long for their weight, thereby subtracting more from the powder space inside the case.

A primer beginning to flatten is not normally a concern. Watch for signs of cratering (flowing around the firing pin and into the firing pin tunnel to form a ridge around the primer indentation) or mushrooming (flowing out into the radius of the mouth of the primer pocket). Piercing would obviously be a bad sign.

Years ago I did an experiment with some 30-06 NM ammunition in which I fired it after tipping the gun forward to put the powder over the bullet and away from the flash hole and vice versa. Downward tipped, the primers were all rounded at their corners. Upward tipped the velocity increased about 80 fps (the load only filled the case just over 80%) and the primers went flat. But no cratering, mushrooming or piercing. There was nothing wrong from those standpoints.

Incidentally, where did you get your FF bullets? I've only seen muzzle loading bullets available from Federal as components. Otherwise, just primers and brass.

When you get hotter temperatures, keep your chronograph handy. You can adjust the loads down to return the original velocity in warmer conditions. That should keep you pretty close to the accuracy node barrel time.
 
I got the bullets from a bulk supplier who got them from a federl over run. As for the pressure, the case was almost full at 26.7 grains.....27 grains would be starting to compress.
The other thing is, the federal fusion is a bonded bullet and the research I have done says they do not like to be pushed too hard, so I was thrilled to get 3155 and around 1/2 MOA where federal lists the factory ammo at 2750 fps.

Also, I didn't say this initially but at 26.7, extraction starts getting erratic indicating pressure. A 26.4 the rounds extract at 3 0'clock in a nice neat pile
..at 26.7 some are at 3'oclock and some at 1 o'clock indicating difficult extraction on some cases.
 
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An overrun would explain it. If you don't mind, what is the length of one of those bullets and what COL are you using? It's odd that the longer, less dense Barnes bullet isn't showing a compressed load in Hodgdon's data but looks like it would in your load (not that a little compression is bad). According to Barnes, the TAC-X-BT is 0.942" long.
 
Unclenick:
The federal fusion's have an average bullet length of .89....which is only 0.03" shorter than the Swift scirocco 62 grains which is the other bullet hodgdon posts data for at 62 grains. I suppose I could fill the cases and tap them, maybe I have a slight"peak" in the middle. Anyway, the Swift bullet is shorter than the Barnes yet the max load is almost a grain less 26 grains of powder. In any case, I am sure that I won't find another accuracy node above 3155 fps simply because the difference in the last two was about 1.5 grains...so if there is another one it is likely around 27.5-28 grains which would probably pierce primers or stick cases.

As for the "case tilting" you mentioned before changing primer flattening or cratering...i usually try to pick a powder that will almost totally fill the case for that reason. For instance I use H4831 and not 4831 SC in my .270 because 4831 is slightly compressed giving more consistent velocities where as 4831 SC leaves room for the powder to settle.

Oh and the COAL is 2.250
 
QuickLOAD sees about 2000 psi and 23 fps difference from 0.03" difference in length with the COL the same. Not a lot. I can't account for Hodgdon's results unless the metal on the Scirocco is very thick. The Barnes has bands to cut the engraving resistance down some, and that may well be doing its job better than I expected.

It dawns on me another factor is the likely cause of your pressure indication. You are getting 3155 fps readings. If I take the Hodgdon Scirocco data and put it an Excel file that derives the exponential relationships between powder and pressure and velocity from the published measured data, it indicates your 26.4 grain load behind the Scirocco should produce 57643 psi and 3069 fps from your shorter barrel (assuming your chamber and bore dimensions match Hodgdon's). Your shorter bullet should be at closer to 55,750 psi and about 3050 fps, if all else were the same. But it isn't. You are using a magnum primer, where Hodgdon is using a Winchester SR primer. That difference was enough to make 150 fps difference in velocity in 223 with a 55 grain V-max in one test (Handloader, 2006; Charles Petty article in the first half of the year, IIRC), and seems the most likely cause here. It is likely raising pressure over Hodgdon's numbers for the same powder charge.

If you don't mind, could you please measure how long the FF boattail is and what the base diameter at the end of the boattail is? I'm trying to take advantage of your good fortune to create a data file for the FF bullet in QuickLOAD.
 
The length of the boat tail portion is 0.07".the diameter of the base of the bullet is 0.195".
From the bottom of the bullet ot bottom of cannalure is .30". I am seating to a 2.250 COAL which leaves about 1/2 the cannalure exposed (assuming your cartridge is trimmed to the minimum 1.750")

Also I re-checked and after filling with 27 grains of CFE 223, and seating a bullet, if I tap the case to get the powder nice and level, it is not truly a compressed load such that you are meeting resistance (crunching). However, the case w/bullet is totally full and after pulling the bullet I can see the dent in the powder where it was sitting....also, there is no "shake" sound.. so I am calling that mildly compresses.

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Another factor could be that this is a new gun with only 500 rounds down the pipe and ruger guaranteed sub moa with the 556 varmint, which naturally means tight chamber. On my Ruger SR 7.62 which is sub moa, I had to seat my Sierra 165 grain BTHP's .015 shorter than the recommended length because, like my girlfriend in highschool, it seems to have a shallow throat
 
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