Developing practice version of SD ammo

[AEuropa]

I tried searching for any similar threads, but wasn't able to find anything. I'm sure that there are similar threads on this topic, but I'm thinking that I wasn't searching for the right phases/words.

Anywho, so now that my AR-15 is finally finished it's time to start developing my loads for it (it has a 14.5" Noveske Afghan barrel, 1:7 twist).

My plinking and 3-gun (well 3-gun-ish; the longest shot for our rifle stages is 25-30 yards) load is going to use Armscor 62gr JPHs. I'm not really too worried about this round being uber accurate, just reliable. My question is about developing my training self-defense replica rounds. For my SD ammo I run Hornady 75gr 5.56 BHTP ammo. The following is my understanding of the process for developing an equivalent round that is as accurate as possible. (I understand that it will never be perfect and I may not be able to reach the 5.56 velocity without exceeding the maximum powder charge. In that case, I will do the best that I can while staying at or below the maximum charge amount).

1) Chrono factory ammo.

2) Load up various rounds, preferably using several different powder choices, incrementally stepping up the charges until you're at (or near) the maximum charge.

3) Chrono the different rounds, always watching for signs of overpressure. Record which rounds (powder type and charge) get closest to the factory ammo's velocity without showing any signs of overpressure.

4) Take the top round choice (or 2) from Step 3 and, using Incremental Load Development, determine the most accurate and consistent round.

This should hopefully give me a round that very nearly matches the velocity and trajectory of my factory SD ammo while also being as accurate as I can make it. Does this process sound right? Am I missing anything?

- Alex

[Joe4d]

Terminal balistics on living targets is kinda beyond the scope of this forum, but it will be awful hard to justify a 300 meter self defense shooting. I also wouldnt think a varmint/target bullet being suitable for the job. A controlled expansion softpoint marketed for hunting larger game would be more suitable for use against something threatening. In my neck of the woods that leans towards canines, stray and coyote attacking livestock.

Winchester, Ultra max and others make 55 gr softpoints for that purpose that have near identical balistics as their cheaper FMJ loads. The Ultra max softpoints remaned loads from midway worked so well and were only sightly higher than FMJ's I pretty much just used them for everything, Was alot easier on the wife not having two different ammo supplies.

[AEuropa]

Sorry, I'm not following you at all. Are you sure that you posted your reply in the correct thread? No where did I address the issue of terminal ballistics against living targets. Furthermore, nowhere did I state that I intend to use a rifle at 300 yards in a self defense situation. My question relates to creating a load that functions similarly to my SD load so that I can practice with a round that has a very similar bullet trajectory at a fraction of the cost. That, to me, is well within the scope and realm of this forum.

Next, why on Earth would you say that a 5.56, NATO-spec, 75 grain BTHP round is a varmit/target bullet? THIS is the round that I use for self-defense...seems like the appropriate application of the appropriate tool.

Lastly, I don't have a wife or anyone else to convince why I choose to do the things that I do.

- Alex

Edited February 14, 2011 by AEuropa

[lefty556]

Alex,

I did pretty much the same thing for 55 grain TAP about three years ago. I started by chronographing the ammo to see what it was doing. Then I went to my manuals and picked a couple of types of powder that I already had that the book said should get me in the neighborhood velocity wise. Then I started working up a load, looking for something that gave me the same kind of groups and point of impact at my zero distance (100 yards in this case). Then I chrono'd the ammo. I actually wound up with ammo running about 80 FPS faster than TAP, but I'm getting the same group size and POI at 100 yards as TAP. Inside 300 yards, I'm within a half a minute of TAP. Since I run an AimPoint for my SD gun, that's good enough. I cant see a target smaller than 1.5-2 MOA at 300 yards.

I realize that there should never be a reason to use a defensive rifle beyond 50 yards or so. That being said, I don't get to choose the circumstances of a self defense engagement, I just have to deal with the fight that picks me. Knowing that I can reliably hit targets out to 300 yards gives me a whole lot of confidence. Confidence in your equipment and abilities is a big advantage, competitively or in a self defense situation.

In your case, I would look at Hodgdon H4895, H335 and IMR 8208 XBR for powders, assuming that you don't have anything on the shelf. I've also had good luck with Accurate 2520 and Ramshot's Tac with 77 and 75 grain bullets. If you're in a bind, you can substitute 77 gr Nosler or Sierra data for 75 Hornady projectiles. DO NOT USE DATA FOR 75 grain VLD's! They are considerably longer, and are generally seated out a bit compared to the 75 Hornady or 77 Nosler and Sierra bullets. Hodgdon's reloading data center has a good bit of info, and is a reliable source of info.

ML

[Too Eazy]

Hey, good idea. I already tried to reply to this but its not showinng up, must've done something wromg. I started testing loads like this last summer. Your plan soumds well thought out. I'm excited to hear your results. So here is what I've narrowed my loads down to.

I started with new winchester .223 cases (still using the same 200 cases to see what they would look like after multiple reloads)

75 gr Hornady bthp (I've also worked up the same load with a no name 75 gr bthp I get from Wideners reloading. It cost about half as much as the hornady so it's great for practice and the min. group size is almost as good as the Hornady but the average groups are no where close to the Hornady, you get what you pay for I guess. Still a great bullet though.)

CCI standard small rifle primer (It is the only one I've used for this load)

26.0 gr of Hodgdon Varget (That's 1.0 gr over Hodgdons max recomended charge)

Case overall length 2.250 with a light crimp from my lee factory crimp die.

I don't have my crono YET, it should be here soon though. So I have no velocity numbers. Sorry. I also want to say that max "published" loads are not always max pressure loads. If you are looking to duplicate nato 5.56 pressures and velocities you'll never get there with "published" max recomended loads. 5.56 nato pressure max is 60,000 cup. Hodgdon max recomended load for a 75 gr bullet (I cant remember which brand) is 25.0 grs of varget, a win. sr primer and I think a col of 2.250 and they list pressure for that particular load at 48,400 cup. I worked up to my load and was very careful. I've seen absolutely no signs of over pressure. And after 4 reloads the 200 pieces of brass still look great. My rifle is a Ruger Mini 14 with a factory 1/9 twist barrel shortened to 14.5 inches with a permanently installed fh and a nato chamber. The action sits in a aluminum Sage International CQB stock and a leupold prismatic sight, which is an awesome sight by the way. I also had the trigger lightened to 3.5 pounds (still a two stage though). With my dads Leupold mark 4 mr/t 2.5-8 power scope my varget starting loads (24.7 grs behind the 75 gr bthp) could barely hold 4 inches at 100 yards. By the time I got to 26.0 grains the groups went down to 1.5 inches average. I think with my slow twist rate and short barrel the heavy bullet wouldnt stabalize until it was moving fast enough in the barrel. Just my oppinion thogh so feel free to enlighten me if I'm wrong.

Anyways, good luck and I hope you post your results here when you get them. As soon as my chrono comes I'll post my velocities. Happy shooting!