223/5.56 Max load advice

[poke5353]

I have a question. I am loading 75gr hornady bthp in a 5.56 chamber. I am using alliant ar-comp powder, LC brass, and cci400 primers at mag length. My big question is where do I stop adding powder? What I mean is I started with alliants load data for 223 77gr SMK. I went from 21.5,21.8,22.1,22.4,22.8,23.1 I ended up with 23.1gr with 2720fps out of a 14.5" barrel with no signs of issues. So loaded up some more at 23.4 and 23.7. This seems like a lot of powder considering alliants load data. I mean thats 1.7gr more. Is this a normal result when considering a 223 chamber to a 5.56 chamber. Also, does anyone see any issues with what I am doing? The only reference I have seen for 223/5.56 is Racshot tac. The Tac 223 load data states 21.7gr vs 23.2 on the 5.56 load data.

Thanks

 

[Edo1]

Re: 223/5.56 Max load advice

Sometimes I think the powder companies are a little conservative with their data due to many reasons. One is that a load developed in cool weather will blow primers in hot weather. Use a chronograph and stop when you get the desired velocity. Are you shooting this load at 600 yards?

 

[poke5353]

Re: 223/5.56 Max load advice

All my tests as of now have been OCW tests.

 

[gunsnjeeps]

Re: 223/5.56 Max load advice

2720 will do you for 600+ yards. MK262 is 2833 out of my Wylde Chambered RRANMA2. My normal load is a 77 SMK, 24 gr Varget and a CCI400 primer for 2700 fps. 24.5 gave me 2750.

Considering you're in a 14.5 inch barrel I think you may have hit a max load someplace in there. How do your primers look? Or how flat are your primers? Have they flowed out more than their original diameter?

CCI 400's are a soft primer, I would think that they have flattened out quite a bit.

 

[poke5353]

Re: 223/5.56 Max load advice

Primers look flat. They are not cratered and I dont have any black around the primer. I have popped some out and they seem to be just as hard to pop out as any other case I have dealt with. The only reason I wanna go higher is because the 23.1 is not the most accurate load. I wanted to see if I could find another node.

 

[Broken_Reticle]

Re: 223/5.56 Max load advice

Some one else might have to speak to this, but how accurate can a 14" barrel be? that isn't much tube for the bullet to hold pressure with on it's trip down the barrel.

Sorry to ask these ?'s in your thread.. but I am new and I am reloading to two ar's and just wanted to know. Does your bullet weight match the twist rate of your barrel?

Cheers

B_R

 

[poke5353]

Re: 223/5.56 Max load advice

Yes it does. I am using a 1/7 twist barrel.

 

[poke5353]

Re: 223/5.56 Max load advice

This is what I came up with after firing them.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3188413#Post3188413