on December 18, 2009 12:14 PM
One of the top self-defense loads for the AR-15 these days is Hornady TAP 5.56x45 75 grain T2.
The only problem with amassing quantities of this ammo is that its expensive (over $1 per round before shipping/tax) and can be hard to find. So I have resolved to roll my own, or at least something close to it.
I say close to it because I am not using the cannelured bullet that Hornady uses, but it is basically the same bullet minus the cannelure. The cannelure probably helps the bullet fragment more, but I think this will still be an effective load without it. (The Mk 262 Mod 0 bullet did not have a cannelure.) What makes this load effective is that it yaws in soft tissue, and the cannelure should have no effect on that.
It's important to note that Hornady specs this only for the 5.56x45 chamber and not the .223 Remington chamber. I have a 5.56 chamber, so all is good there. The reason I bring this up is that the initial published load data I have found is for the .223 Remington chamber, so I might end up going over the published data, I don't know yet. I'm wanting to reach 2700-2750 fps out my 16" barrel, which should be close to the published 2665 fps out of a 14.5" barrel that Hornady lists. I may be able to do that with the published data, I don't know yet.
I have selected Ramshot's TAC powder for this load, and here is there load data for the Hornady 75 grain BTHP bullet that I am using.
TAC 75 HDY BTHP 21.2 2,511 23.6 2,790 50,760 2.260
So the starting load is 21.2 grains and makes 2511 fps out of a 20" barrel with a .223 chamber. The max load is 23.6 grains and makes 2790 fps with 50,760 psi of chamber pressure. So even that is below the 55,000 psi SAAMI spec for .223, things are looking good.
If I had to guess, I would expect my final load to be around 24.5 grains or less.
I'll be updating this post as load development progresses.
Test #1
Test #2
I say close to it because I am not using the cannelured bullet that Hornady uses, but it is basically the same bullet minus the cannelure. The cannelure probably helps the bullet fragment more, but I think this will still be an effective load without it. (The Mk 262 Mod 0 bullet did not have a cannelure.) What makes this load effective is that it yaws in soft tissue, and the cannelure should have no effect on that.
It's important to note that Hornady specs this only for the 5.56x45 chamber and not the .223 Remington chamber. I have a 5.56 chamber, so all is good there. The reason I bring this up is that the initial published load data I have found is for the .223 Remington chamber, so I might end up going over the published data, I don't know yet. I'm wanting to reach 2700-2750 fps out my 16" barrel, which should be close to the published 2665 fps out of a 14.5" barrel that Hornady lists. I may be able to do that with the published data, I don't know yet.
I have selected Ramshot's TAC powder for this load, and here is there load data for the Hornady 75 grain BTHP bullet that I am using.
TAC 75 HDY BTHP 21.2 2,511 23.6 2,790 50,760 2.260
So the starting load is 21.2 grains and makes 2511 fps out of a 20" barrel with a .223 chamber. The max load is 23.6 grains and makes 2790 fps with 50,760 psi of chamber pressure. So even that is below the 55,000 psi SAAMI spec for .223, things are looking good.
If I had to guess, I would expect my final load to be around 24.5 grains or less.
I'll be updating this post as load development progresses.
Test #1
Test #2
Barrel twist rate?
Just curious as 75Gr is at the high end of a 1 in 9 in .223 that so many peoples AR's are. Wouldn't want you to get your hopes dashed if accuracy sucked.
TXGunGeek
1 in 7. My test loads have been really accurate.