Reloading .223 for a NATO chambered AR

[Rynnäkökivääri 62]

Like the thread topic says, I own an AR-15 with a 16" barrel that has a 5.56 NATO chamber, it's a Bushmaster 1:9" twist barrel if that matters. I am gearing up to reload .223 and I have been looking at the differences between .223 and 5.56 and from what I can tell it's really just the throat that is the one consistent difference.

So what should I do to get the best performance out of my AR when reloading? I am guessing using heavier bullets (62- 69 grains?) and seating to the max OAL that the magazines will permit? I understand I want the bullet to be as long as possible to better fill the "sloppier" throat of the NATO chamber, are there maybe different profiles that are better suited as well?

[Cotys]

The 1:9 twist rate will be a limiting factor on how long your bullets can be. Most people shoot a 1:7 or 1:8 twist for heavier / longer 5.56 rounds. Some 1:9 do OK with 69, 75 or even 77 grain bullets. Some don't like them and you see them key-hole at the target.

Max COL is 2.25" which is what is recommended for 69, 75 and 77 grain bullets. Probably the majority of people shoot plain old 55 grainers in their 1:9" Bushmasters.

If you are going for long distance, 600 meters +, the heavier bullets hold up well. I load 75 grain Hornady for my long range varmint AR.

[Nuke8401]

I have an ARMLITE 16" middy upper, 1:9 twist.

I load 68gr Hornady BTHP with 25.0 gr RAMSHOT TAC OAL 2.260"

This load gives me about 1.5 MOA or better and matches (verified at the range) my Leupold CM-R2 BDC out to 400 yds (matches the BDC calculator out to 500yds). I use Lee 223 dies and use the Factory Crimp Die set lightly. I entertained trying to get 5.56 specific dies (don't know if there is such a thing) but these results are good enough.

The 25.0 (25.4 MAX) is listed under the NATO loading (69gr SMK) vice the 223 loading as the limit there is 24.2

I have loaded them at 24.2 and there is no real different between the 24.2 and 25.0 accuracy wise.

I tried 75gr Hornady steel match and the groups opened up, same results with 75gr hand loads.

I'm not as worried about wind as I am hitting reactive steel targets with a little more weight.

My other load is the Hornady 55gr FMJBT (Bulk) 25.0gr TAC which has about the same POI at 200 as the 68gr.

So I shoot the 55's out to 200-300, and the 68's whenever there is steel or >300.

David E.

[Rynnäkökivääri 62]

I rarely have access to a range longer than 150 yards so that's where most of my shooting is going to occur. The 68gr hornadays sound good. My bulk ammo will be either whatever cheapest bulk 62gr I can find though.