Reloading .223, need chrony comments!

[ol' poke]

Ok reloading experts, how did I do with my first adventure into chronography?

I'm just started loading my own match-grade .223 ammo.
My objective is to load the most accurate 100 yd. ammo at the least cost.
My rifle is a Rock River NM-A4. 20" Wylde, stainless barrel w/1-8" twist.

My ammo components are:
69 gr. Sierra Match King BTHP
Alliant Reloder 15
Remington 7 1/2 primers
Winchester brass

I loaded 100 rounds, 10 each of 23.7, 23.9, 24.1...up to 25.5 grs and went to the range.
After setting up my chrony and firing a dozen rounds to be sure the chrony was recording
results and to "warm up" the barrel, here are my results:

Charge Max Min Avg. Spread Standard Deviation
23.7 2609 2501 2544.6 108 36.4
23.9 2635 2554 2595.3 81 26.3
24.1 2656 2588 2629.4 68 21.2
24.3 2699 2640 2666.5 59 19.8
24.5 2715 2650 2681.3 65 23.4
24.7 2777 2688 2718.1 89 24.3
24.9 2777 2715 2738.6 62 23.5
25.1 2789 2732 2763.1 57 20.1
25.3 2818 2754 2777.5 64 19.9
25.5 2867 2789 2811.6 78 21.4

Does the above data look decent? Some reading I've done suggest I should be looking for
a standard deviation in the single-digits - I'm far from single-digits, should I expect that consistency?
It looks like my best load would be at 24.3 grs. with 25.3 a close second.
Should I chrony up some more at 24.2-24.4, and 25.2-25.4, looking for another, sweeter spot?
Is this how it's done?
Should I repeat the entire process to provide additional, hopefully duplicate data?
If I'm on the right track, my next adventure is to repeat the process for a 300yd round using 77 gr. SMKs.
Any suggestions there?

Sorry for the length, and thanks in advance!

 

[gmcttr]

When developing loads for service rifle competition (years ago), the chronograph data was of interest, but the real answer to the "best" load came from the group sizes.

What loads grouped the best?

 

[ol' poke]

Hi gmctr: I was shooting with my son and we were alternating every 20 rounds. The best group came from 25.3, followed closely by 24.1.

I'm trying to eliminate as many variables as possible to produce the most accurate ammo possible. I realize that two shooters imports a HUGE variable, but this won't impact the chrony measurement for this part of the process.

 

[BE Mike]

Hi gmctr: I was shooting with my son and we were alternating every 20 rounds. The best group came from 25.3, followed closely by 24.1.

I'm trying to eliminate as many variables as possible to produce the most accurate ammo possible. I realize that two shooters imports a HUGE variable, but this won't impact the chrony measurement for this part of the process.

You might try some 75 gr. BTHP and see how they group. I'm using Reloder 15 with 75 gr. BTHP. With my RRNM A4. I broke in my barrel using the recommended procedure.

 

[Ericpwp]

Agree with group size. That's the whole point, right? M855 has a low spread, but nobody claims it to be very accurate ammo.

I say redo the test with less variables.

 

[padawan]

Agree with group size. That's the whole point, right? M855 has a low spread, but nobody claims it to be very accurate ammo.

I say redo the test with less variables.

+1 for group size here too. Accuracy trumps speed for us. IMO.

 

[craigkim]

Just throwing it out there, but I was able to load up Hornady 55 FMJ-BT and shoot sub moa with it at 100 yards using TAC. I used same headstamp lake city brass. I think I paid 6 cents each for the bullets.

 

[Mgderf]

+1 for group size here too. Accuracy trumps speed for us. IMO.

Yep.That paper target doesn't know, or care, how fast those bullets pass through.
Worry more about the groups first.

 

[red_zr24x4]

After you figure out what charge weight groups the best, start playing with the seating depth to tighten them up some more

 

[Woobie]

To get really low SD, you're going to have to mess with neck tension and concentricity. Turning necks kinda sucks and I don't do it anymore. Tension you're kind of handicapped on in a semi auto. As someone else mentioned, seating depth plays a big role in this, although, once again, you're a bit handicapped with a semi auto. But you can still make some big gains with the room you have to play with.

As others have said, SD isn't as big of a deal in the 100 yard game.

 

[Leo]

I have used your load, except I usually used CCI primers. That is a good combination for accuracy.

The 1% standard deviation is plenty good, like woobie said, you can get 1/2 % deviation, but that takes a lot of extra work, like benchrester tedious reloading. I only ever got that involved for the 600 yard matches, and PALMA where loose velocity gets you vertical strings in your group. For 200 and 300 yard work anything around 2700 fps with a 69 gr Sierra was plenty to clean the target. The 69's group pretty good at that speed. Velocity is your friend in fighting side winds, but flight time is pretty short inside 300 yards. Depending on your barrel, 24.5 grains might be a good maximum, that is generally where my primers started to flatten out pretty bad, suggesting max pressures. I know part of that was that I always used premium match barrels that were a little tight.

 

[padawan]

After you figure out what charge weight groups the best, start playing with the seating depth to tighten them up some more

Any thoughts on 'kissing the lands' seating depth or letting it 'jump'?

 

[red_zr24x4]

You're limited by the "free" room in the mag.
On my Savage 223 shooting 60g V-max I'm seating out to the length of the blind mag.
Only way to go longer would be to single load.
My best answer is to see what works best in your rifle

 

[Ericpwp]

Yeah, if I kiss the lands in my 5.56 AR, there is no way I'm getting them in a mag.

Also, I see higher pressure signs on the brass, even at min loads.

 

[natdscott]

Re-check on another chronograph. Those numbers seem slow.

Edit to add: Ah. But uh, not much more powder should be added to try to chase velocity. 25.5 is plenty.

-Nate

 

[sloughfoot]

100 yard accuracy is kind of meaningless because the bullet is rising into the target. 24.5 of Re15 works very, very well out to 300 yards with the 69. It will work at -10 F and +100 F.

The 75 Hornady BTHP over the same charge is slightly larger group, but I have shot many cleans at 300 yards with 75's over 24.5 of RE15 with several rifles. And so have lots of fellow shooters. The 75 tolerates wind changes at 300 better than the 69. That is it's advantage. The abiity to stay in there with a mild wind change.

Don't try to re-invent the wheel. Thousands have been shooting 69's out of 20 inch AR rifles for years. It is kind of painful to watch guys agonize over things that have been settled for years by HP shooters.

A local shooter, who will remain nameless, discovered a great shooting load using 26.5 grains of RE15 under a 69. Until July came. Then we were trying to pick his primers out from under his trigger so he could finish his string. He became a believer quickly.

I shot for 30 years without a chrony. The only thing that matters is results on target. I chronographed some of my loads and all it did was to scare me. I have not used one since. I use results on target.

 

[BE Mike]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^THIS^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^sloughfoot has been there and done that and has the t-shirt.