Stabilizing Heavier Bullets

[sta500rdr]

Ok, I am putting together 5.56/223 loads and I am approaching the top of my bullet weights for my 1:9 twist barrel.

First, can I load a .223 stamped brass cartridge up to a 5.56 load spec? The case measurements seem to be identical, I just wasnt sure if they can handle the same charge.

Second, in order to stabilize a 68 or 75 gr bullet weight, would I be better off with a higher velocity or lower velocity? I have had some success with them being stable at 200-300 yards but have not taken them out much further than that. This is what I am loading thus far.

Winchester Brass
CCI Small Rifle Primer
Hornady 68 Grain BTHP
H 322 21.6 grain (Approx 2500 fps)

 

[rcmodel]

First, can I load a .223 stamped brass cartridge up to a 5.56 load spec?

Yes, and no.

More then likely all you can find is going to be .223 data.
5.56 data is not published by any of the reloading manuals except for Hornady.
They list 5.56 data, but only with the 68 & 75 grain bullets.
They used Winchester commercial .223 cases.

Some .223 brass is thinner then some GI brass.
On the otherhand, some .223 brass is heavier then some GI brass.
Only way to find out is weigh it and compare it to 5.56 GI brass.


Increasing velocity will spin the bullet faster, which increases stability.
Increased velocity in slower twist has the same effect as a faster twist at lower velocity.

rc

 

[EddieNFL]

I am putting together 5.56/223 loads and I am approaching the top of my bullet weights for my 1:9 twist barrel.

Think length, not weight.

Increased velocity in slower twist has the same effect as a faster twist at lower velocity.

True, but the velocity increase necessary to compensate for even a .5" difference in twist rate is rather significant.

 

[sta500rdr]

Thanks for the info. The manual I am using is the Hornady manual. There is a section like you said listed for the 5.56. The two bullet weights listed are the two that I will most likely end up using.

From what I gather from your responses is that the higher the velocity with a heavier bullet, the more stable it is most likely to be down range. Again, trial and error is most likely going to tell the tale. Thanks guys!

 

[snuffy]

RC has it right, as usual. So does Eddie. The faster you can push them, within pressure limits, the better they'll stabilize. My 1-9 bushmaster 20" bbl. does well with the 69 grain nosler match HP. But won't completely stabilize 75 grain Hornadys.

500rdr, you're just going to have to do some experimenting to know for sure. You might need a different powder. I never tried H-322 in .223, so I can't say how it will do.

BTW, glad to see ya back RC, where ya been?

 

[sta500rdr]

The H 322 powder has been outstanding for my 50 and 55 grain target loads. I figured I would start there and see how it does moving down the range and with heavier bullet weights.

The only complaint I have with the hornady manual is that it does not list any pressures. Do you guys happen to know where I can find this information?

 

[rcmodel]

You don't really need to know.

Published max loads in all reloading manuals are within SAAMI pressure spec for the caliber in question.

Trying to go above listed max loads is playing with fire.

rc

 

[EddieNFL]

Trying to go above listed max loads is playing with fire.

But when you realize it's too hot to hold, it's too late to let go.

 

[sta500rdr]

I guess in a round-about way that was what I was asking. I was assuming that the max load was the highest pressure allowed by that caliber. I just know that some manuals publish pressures in them, Hornady chooses not to in their manual. I am not really comfortable shooting max loads anyway unless its needed for accuracy.

And I do agree, going above max load is just asking for trouble. Never have, never plan to.

 

[MachIVshooter]

Trying to go above listed max loads is playing with fire.

Heed this warning, but know also that it is done with great frequency and no ill effects by people who know what they're doing. Published data has a pretty sizeable margin of error on the side of caution, and some guns can just take a whole lot more pressure than others.

We wouldn't have many of the performers we do today if people hadn't played with that fire in years past (though good ol' Elmer Kieth and Dick Casull sent quite a few revolvers to handgun heaven in the process)

Also remember that not all load data is created equal. I bounce between a half dozen manuals, some of them having substantially different max loads with a given powder.