5.56 AR Only Loads

[WeR0206]

I finished load development with.223/5.56 77 SMK and AR-Comp a week ago on my 14.5" AR-15 with an Aimpoint red dot sight. I strongly advise using a chronograph to compare to a known load, such as MK 262 Mod 1, as you progress up the ladder. I backed down around 0.6 grain and got the following results from 20 shots at 100 yards. If I can attain this accuracy at 100 yards with a 14.5" barrel and red dot, I believe I'm ready for anything I plan to use the SBR for in the future. The next stage will be to shoot these through another of my ARs, a 14.5 SBR with a 1-6x variable scope, to do a more critical accuracy assessment.

I love AR-Comp but ive been avoiding doing load development recently with Alliant powders since they will practically be unobtainable in the US pretty soon. Im switching to mainly VV (N140) for its excellent price & performance…also doing some with AA 2520 and TAC for mk262 clone loads. TAC kicks ass as a cheap all around easy metering powder to have on hand.

 

[bf2junky]

Love TAC. Performs even better when you load it on the hotter end of the range.

 

[WeR0206]

Love TAC. Performs even better when you load it on the hotter end of the range.

I just shot some 77 smk’s in LC 556 brass @2.246” with 25.0gr TAC with zero burrs etc on the brass and primers were fine. Avg speed out of a 16” Wylde barrel was 2806. Black Hills 77 otm in same barrel is 2692. 2806 is pretty smoking fast for those 77gr pills. Love it!!

Side note there is a free reloading software called Gordons. I somehow just found out about it this last weekend and it helps a lot with load development. You give it inputs for your chamber, COAL, spent case volume, bullet length, pressure limit, etc and it spits out the estimated pressures and velocity for each step in your ladder.

 

[jLorenzo]

I finished load development with.223/5.56 77 SMK and AR-Comp a week ago on my 14.5" AR-15 with an Aimpoint red dot sight. I strongly advise using a chronograph to compare to a known load, such as MK 262 Mod 1, as you progress up the ladder. I backed down around 0.6 grain and got the following results from 20 shots at 100 yards. If I can attain this accuracy at 100 yards with a 14.5" barrel and red dot, I believe I'm ready for anything I plan to use the SBR for in the future. The next stage will be to shoot these through another of my ARs, a 14.5 SBR with a 1-6x variable scope, to do a more critical accuracy assessment.

Pics?

 

[MustangGreg66]

I just shot some 77 smk’s in LC 556 brass @2.246” with 25.0gr TAC with zero burrs etc on the brass and primers were fine. Avg speed out of a 16” Wylde barrel was 2806. Black Hills 77 otm in same barrel is 2692. 2806 is pretty smoking fast for those 77gr pills. Love it!!

Side note there is a free reloading software called Gordons. I somehow just found out about it this last weekend and it helps a lot with load development. You give it inputs for your chamber, COAL, spent case volume, bullet length, pressure limit, etc and it spits out the estimated pressures and velocity for each step in your ladder.

Interesting. TLDR: Case volume matters a lot at the upper end of pressure.

I found it interesting you're not getting any pressure signs with that load. I've been loading some 77gr SMK 2nds @2.255" and 25.0gr of TAC for spinner targets in 3gun. I got some ejector smears on the brass and can tell it's pretty hot. I'm not getting the brass back so it's one and done for this purpose and I'm fine with it.

I tried to duplicate it in Gordon's reloading tool and it took me a while to match your pressure results. The difference I found was the brass I'm reloading measured case volume (h20 on scale) at 30.00gr for LC '95 brass where yours is 30.88gr. That difference in case volume gives me 67k psi to your 61k. I've been using random year LC and still getting some pressure signs with that load, but I'm ok with it for the small number of these rounds I use.

 

[WeR0206]

Interesting. TLDR: Case volume matters a lot at the upper end of pressure.

I found it interesting you're not getting any pressure signs with that load. I've been loading some 77gr SMK 2nds @2.255" and 25.0gr of TAC for spinner targets in 3gun. I got some ejector smears on the brass and can tell it's pretty hot. I'm not getting the brass back so it's one and done for this purpose and I'm fine with it.

I tried to duplicate it in Gordon's reloading tool and it took me a while to match your pressure results. The difference I found was the brass I'm reloading measured case volume (h20 on scale) at 30.00gr for LC '95 brass where yours is 30.88gr. That difference in case volume gives me 67k psi to your 61k. I've been using random year LC and still getting some pressure signs with that load, but I'm ok with it for the small number of these rounds I use.

View attachment 8664999

Yeah case volume seems to be a very sensitive input, even changing it by hundredths of a grain will swing chamber pressure by a few hundred psi. My measurements were actually closer to 31 grains on avg but I errored on the side of caution and used the smaller of my numbers when I saw how much slight differences could swing chamber pressure.

Most of my LC brass was newer 21-24ish.

Bullet length was also a big driver. I measured about 10 of my 77 smk’s and they were well under the default value of 1.0”….more like 0.977”. That also allows for slightly higher loads before hitting pressure limits compared to the 1” input.

Here’s a pic of the brass. The row furthest from camera was the 25.0gr load, there were definitely some swipes but no burrs (I also just installed a fresh sprinco ejector spring in my bcm bolt):

 

[Snuby642]

So you can shoot the difference in one hundredth of a grain? 0.003 thousands worth of case capacity?

Nice.

Last I heard LC brass was made at multiple locations. It seems to vary instead of brass made at one location it seems. I use it for blasters to use up odd lots of powder and bullets.

 

[thedude824]

Anyone know which bushings are needed for Starline 556 and Lake City brass?

 

[wvfarrier]

Right now I am working on loads for these Hornady 75gr Boat Tail Soft Points. I have tried Power Pro 2000mr, and Benchmark, neither were impressive with the lowest velocities showing the best accuracy (2moa ish). I slapped together a ladder using Varget and plan to try it tomorrow.

 

[MustangGreg66]

^Double cannelure? I've never seen that before. How odd

 

[45-90]

^Double cannelure? I've never seen that before. How odd

It's fairly common to have a double cannelure on bullets.
Reason is for different cartridge overall lengths to fit common actions the bullet might be used in single shot, or lever action...or limited by magazines of a common factory rifle and cartridge it might be chambered in, like maybe 338 Federal and 338 Win Mag using the same bullet but need a different area crimped to meet COAL for each common cartridge the factory intends to load this bullet.

 

[WeR0206]

Anyone know which bushings are needed for Starline 556 and Lake City brass?

It depends on how much neck tension you want. Load your bullet into an empty case that has been resized. Measure the OD of the neck. This is your reference number. Subtract from this number how much neck tension you want and that will be your bushing size.

For me I use LC 556 brass. A loaded case has neck OD of 0.247”. I want 2 thou of neck tension so my outer diameter of the neck should be 0.245” which is the size of the bushing id need (I use expander mandrels to set my neck tension). If I wanted 3 thou Id use a 0.244” bushing.

 

[Snuby642]

Why would you screw around with all that shit every time you change brass?

You get a Sinclair mandrell die 0.002 under and never have to check the brass again unless you have a neck turn chamber.

Instant consistancy no math or bullshit ever all the slop goes to the outside and group sizes drop significantly.

 

[WeR0206]

Why would you screw around with all that shit every time you change brass?

You get a Sinclair mandrell die 0.002 under and never have to check the brass again unless you have a neck turn chamber.

Instant consistancy no math or bullshit ever all the slop goes to the outside and group sizes drop significantly.

View attachment 8673437

Yep. This is why I use expander mandrels (either separately or in the FL die). I dont fuck with bushings

 

[Snuby642]

 

[thedude824]

It depends on how much neck tension you want. Load your bullet into an empty case that has been resized. Measure the OD of the neck. This is your reference number. Subtract from this number how much neck tension you want and that will be your bushing size.

For me I use LC 556 brass. A loaded case has neck OD of 0.247”. I want 2 thou of neck tension so my outer diameter of the neck should be 0.245” which is the size of the bushing id need (I use expander mandrels to set my neck tension). If I wanted 3 thou Id use a 0.244” bushing.

I greatly appreciate it. I was being super lazy. I bought a bunch of new primed LC cases and wanted to order the bushing at the same time. This is for semi so I’ll do a 0.243” for LC and I’ll seat a bullet into the Starline brass (that’s here) and measure and then just pull it.
I’m still a little new to reloading for long range precision. I have mandrels for each caliber to run through new brass or if the necks are dented, but I load for semi and bolt in several of them and bushings just seemed a little easier and has so far worked pretty well. There are so many rabbit holes one can fall into when it comes to loading ammo.

 

[Snuby642]

So what are you loading 6mm or 223?

 

[thedude824]

So what are you loading 6mm or 223?

I guess I still need to measure case thickness

 

[Snuby642]

You may have a typo of .243 instead of .223 or your too toasted to throw powder. Lol

 

[WeR0206]

You may have a typo of .243 instead of .223 or your too toasted to throw powder. Lol

We were talking about outside diameter measurements of .223 case necks. If it was inside diameter then the numbers would be closer to .223. For my LC brass I go for an inside diameter (set with expander) of .222” which equates to an OD of .245” and neck tension of .002”. If I used a bushing die I would use a .245” bushing for my LC brass

 

[Snuby642]

Ok.
I'm toasted but just cooking. Lol

I was confused about what was being measured. I don't measure necks inside or out. I just run the mandrell everytime.