5.56/223 MiHec 75gr NATO:favorite powder/ loads?

[zubrato]

Hi everyone,
Can't seem to find info regarding this projectile, will be my first foray into casting for my AR15.

My goals: close range blasting loads. I can gut a spare carbine buffer to decrease cycling weight, perhaps insert a delrin rod for the deadblow effect.
I'd like to shoot steel without destroying it at a little over pistol engagement distance, happy with minute of man accuracy for now.

AR: 1-7" twist, midlength gas, FA carrier. I usually run an H2 buffer, but I plan to gut my carbine buffer and use that for lead loads.

I'll be gas checking/CR lubing. Alloy: COWW + 2% tin water dropped.

Any tips regarding powder selection, burn rate, or just share experience?

I have H335, CFE223, IMR4895/3031, and a variety of pistol magnum powders that I doubt would cycle.

Would love to hear back from you guys, there's so little info despite the large number of people who bought molds. I assume this is because everyones busy, or casting for 223 isn't something to write home about.

Out of curiosity, do the cast loads pop water jugs like the jacketed 223's?

[Gunnut 45/454]

Don't shoot that boolit ! But 18.5 gr of the IMR4895/3031 should get you at a starting point with full function. This works with my 55gr NOE boolit. And no you don't have to change anything. I use a H2 buffer in both of my 16" Carbine gassed AR's. You might be able to go lower in powder with a heavier boolit. I don't PC my boolits so I try to keep them below 1900 fps as accuracy goes down hill past that. The point is you have to achieve at least a 30,000 PSI load to get function in any AR regardless of gas length!

[clearcut]

My 1:7 with a 68 grn. gc PC'd I found a node at 21 grn. IMR 4895

[zubrato]

Thank you guys for the excellent information.
I have given up the idea that this is a boolit I can shoot at steel, I have a very strong feeling it will do exactly what fmj's do after shooting a few of them at the range. Would probably tumble and fragment pretty well, too.

I am casting with coww +2% tin water dropped into ice and I only sort for visual defects not weight, use annealed gator gas checks and lube with carnauba red. Lubed and gc' they weigh in at about 72gr
I wasn't able to finish working up my loads, but saw h335 shot patterns rather than groups, was more prone to wild fliers than the Imr 4895 which cycled an H2 buffer in a 16" bcm middie at 19.5 or 20gr I believe.
I wasn't able to print my best groups or bench rest, but groups slowly opened up from 1" to 3-4" iron sights seated at 25yards. I was being rushed by the RO's for closing time since I got there late after work :/

I estimate even more promise lies in H4895 since it has smaller grains, and from what I read has smaller ES in reduced loads.

This was just a preliminary test more for function, and I was very pleasantly surprised that I found accurate loads that would cycle an H2 buffer with cast as you mentioned gunnut.

I'll be doing more detailed accuracy tests in the coming weeks where I can find time.

One thing bugs me, but I assume it's just the nature of the beast. I have to break sprue just before it solidifies and I don't quite get clean bases. A fraction of a second later and I have to beat it open and the bullets are smashed to one side.

Casting for 223 is an eye opening experience, as I initially believed was too tedious and difficult, turned out to be not as bad as I thought including gas checks, culling defects, and accuracy.

I would recommend a lot more guys here pick up a mold and stock up on M193 before November.

It's doable, and it isn't as bad as everyone thinks.

[Gunnut 45/454]

That's exactly why I got into casting for the 5.56mm AR's last shortage caught me low on Bullets for reloading and I didn't want to burn up my stash of Factory ammo. So the options were spend way to much for what ever ammo I could find. Or get a mold and gas checks and shoot more for less. My cast loads work very well out to 200 yards -minute of man. Excellent for CQB training. And yes unless your shooting at AR500 steel will zip right through at 100 yards or less. Ask me how I know!:wink:

[zubrato]

Update!

Was able to take a few loads out last weekend, both IMR4895 and H4895 with interesting results!

Firearm: BCM 1:7" 16" mid-length gas system on lightweight profile barrel, with H2 buffer

IMR4895 proved very accurate at lower charges like 18.5 & 18.7gr(most accurate)
18.5gr felt like the bare minimum for reliable (clean gun) operation, and locked bolt open. Anything below this did not cycle the bolt/buffer enough to fully eject or load the next round.
Problems with IMR stem from it being a long stick powder, and in so many ways it is NOT ideal.
Cases have unburned IMR sticks imprinted into the case shoulders, around the case mouth, were present in the barrel extension, and in the trigger group where the trigger felt crunchy after only a few shots and I was honestly waiting for trouble with trigger reset.
Not to mention inconsistencies loading the cases due to powder bridging in a .22 cal case mouth. Had to weigh each charge and trickle up, all of these problems combined really rules this powder out for me despite it's function and accuracy.

H4895 was accurate and ran with far more oomph at lower charges than the IMR powder, measured far more consistently with no powder bridging in any of my measures (RCBS competition uniflow/LEE ppm)
However, I would not consider my load workup complete, as I feel h4895 can be loaded quite a bit lower than IMR with perfectly reliable function. H4895 cycled the action far more robustly at 18.3gr than IMR at 19gr, and both exhibited about the same best group accuracy. In my workup I used iron sights at 50yds prone, so the results in each were about the size of a fist including about one flier per 10 round group. Excluding the flier best group was about 1.5" with 18.5gr and iron sights. I suspect you could wring tighter groups with a scope, and sorting boolits by weight (something I chose not to do)
However, I feel the unburned sticks of IMR in the barrel, barrel extension, chamber, and trigger group may have a role in some of this.
I would definitely like to work down from 18.5gr H4895 to find a load that will reliably cycle the action, burn relatively clean, and group consistently.

Now my favorite part!
I shot at an AR500 gong at 50 yards, and hoped for the best. Even 25 yards and in the loads I worked up DID NOT DENT OR CRATER AR500 STEEL and they pop water jugs almost the same as 5.56!
These make for an EXCELLENT plinking round, and I'm very happy. My steel plates will last longer, cases will last longer, and plinking with 72 or so grains is more conservative with lead than my 9mm!
I shot about 15 of them at an AR500 plate and after shooting some 9x19 or 38spl I couldn't tell where they hit.

For water dropped COWW+ 1-2% tin, casually culling for glaring defects, I'd say a 10 shot group (excluding a wild flier) of 1.5in is GREAT(for a small cal autoloader) and there's a lot of folks who won't try because they're sure it wouldn't work. I know because I was one of them!


There's hope gentlemen!