5.56 AR Only Loads

#601
Qpski said:
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.
Click to expand...
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.
 
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#603
bf2junky said:
Love TAC. Performs even better when you load it on the hotter end of the range.
Click to expand...
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.

1744692751303.png
 
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#604
Qpski said:
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.
Click to expand...
Pics?
 
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#605
WeR0206 said:
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.
Click to expand...
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.

Screenshot 2025-04-15 121350.png
 
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#606
MustangGreg66 said:
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
Click to expand...
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):

IMG_3172.jpeg
 
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#607
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.
 
#609
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.

20250425_150406.jpg
 
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#611
MustangGreg66 said:
^Double cannelure? I've never seen that before. How odd
Click to expand...
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.
 

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#612
thedude824 said:
Anyone know which bushings are needed for Starline 556 and Lake City brass?
Click to expand...
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.
 
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#613
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.

TargetDesign_Black_White_1280x.jpg
 
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#614
Snuby642 said:
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
Click to expand...
Yep. This is why I use expander mandrels (either separately or in the FL die). I dont fuck with bushings
 
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#616
WeR0206 said:
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.
Click to expand...

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.
 
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#620
Snuby642 said:
You may have a typo of .243 instead of .223 or your too toasted to throw powder. Lol
Click to expand...
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
 
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#622
WeR0206 said:
Yep. This is why I use expander mandrels (either separately or in the FL die). I dont fuck with bushings
Click to expand...
I turn down the expanders in my fld's so they straiten case mouths and pre-expand far under size on the neck.

And separately bring them to size with the mandrell die.

Something about that procedure dropped groups 20% and some loads a little less some more but every load improved enough to see results.

Brass also runs better in the fld's .

Get the necks " straitened out" and other things fall into place / results of changes are easier to measure.

Not an expensive tool just another step, well worth it to me.
 
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#623
Projectile: 77gr SMK
Primer: CCI 450
Powder: 27gr AA2520
Case: Shell Shock Tech NAS3
COAL: 2.255"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2880fps
SD: 10-20
Accuracy: 1-1.5MOA
 
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#624
Wormydog1724 said:
Projectile: 77gr SMK
Primer: CCI 450
Powder: 27gr AA2520
Case: Shell Shock Tech NAS3
COAL: 2.255"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2880fps
SD: 10-20
Accuracy: 1-1.5MOA
Click to expand...
are you resizing and re using the cases? I asked shellshock and they said that the NAS3 rifle cases aren't reloadable.
 
#626
Wormydog1724 said:
Projectile: 77gr SMK
Primer: CCI 450
Powder: 27gr AA2520
Case: Shell Shock Tech NAS3
COAL: 2.255"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2880fps
SD: 10-20
Accuracy: 1-1.5MOA
Click to expand...
Where/How did you source the Shell Shock NAS3 cases to load? Those seem really interesting.

I'm getting similar velocity, but from a stout load of Varget in a 24" barrel. These do show some pressure signs with ejector smears and flattened edge of primers. I haven't loaded them in those cases more than once.
Projectile: 77gr SMK
Primer: Fed GMMAR
Powder: 25.2gr Varget
Case: LC '95
COAL: 2.260"
Barrel: 24" WOA
Velocity: 2885fps
SD: 11
Accuracy: ~0.6MOA
 
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#630
For science! Not giving powder charge. If your savvy with Gordon's you'll be able to figure it out.

Shell Tech NAS3 cases 31.8gr H2o virgin capacity - 33.14gr H20 fired weighed on FX120
53gr Vmax
COAL: 2.292
cci 450
A lot of TAC
3105fps SD 23.8
.750" @ 50y
Huey G2 Red dot with 3 x magnifier
Barrel is Craddock 8T 223W 10.5" Carbine Gas length with adj block.
Precision Armament Efab
I couldn't tell if it had much muzzle flash because I momentarily Blacked out from the concussion every shot.
That's an exaggeration, but It's obnoxiously loud.
Also shot some 60gr Vmax. but they didn't group as well. 1.128" at 50y still not terrible for a shorty. Both the 53 & 60's shot the tightest at the upper end of the ladder. 60 vmax were 3021fps & SD 26.8

The magnum primers didn't have any cratering, but good grief this speed is what I'd expect from 5 or 6 inches more barrel.
Per Gordon's this should be 59,868psi Also per Gordon's it shouldn't be going nearly this fast. That said Gordon's is very close with N540, N550, AA2520 in brass cases, but under estimates speed across the board for the NAS3 cases. From 10.5" - 26" doesn't matter.
1752112378009.jpeg

1752112435869.jpeg
 
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#631
357Max said:
For science! Not giving powder charge. If your savvy with Gordon's you'll be able to figure it out.

Shell Tech NAS3 cases 31.8gr H2o virgin capacity - 33.14gr H20 fired weighed on FX120
53gr Vmax
COAL: 2.292
cci 450
A lot of TAC
3105fps SD 23.8
.750" @ 50y
Huey G2 Red dot with 3 x magnifier
Barrel is Craddock 8T 223W 10.5" Carbine Gas length with adj block.
Precision Armament Efab
I couldn't tell if it had much muzzle flash because I momentarily Blacked out from the concussion every shot.
That's an exaggeration, but It's obnoxiously loud.
Also shot some 60gr Vmax. but they didn't group as well. 1.128" at 50y still not terrible for a shorty. Both the 53 & 60's shot the tightest at the upper end of the ladder. 60 vmax were 3021fps & SD 26.8

The magnum primers didn't have any cratering, but good grief this speed is what I'd expect from 5 or 6 inches more barrel.
Per Gordon's this should be 59,868psi Also per Gordon's it shouldn't be going nearly this fast. That said Gordon's is very close with N540, N550, AA2520 in brass cases, but under estimates speed across the board for the NAS3 cases. From 10.5" - 26" doesn't matter.
View attachment 8724978
View attachment 8724979
Click to expand...
What magazine did you use to shoot at that COAL?
 
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#632
357Max said:
For science! Not giving powder charge. If your savvy with Gordon's you'll be able to figure it out.

Shell Tech NAS3 cases 31.8gr H2o virgin capacity - 33.14gr H20 fired weighed on FX120
53gr Vmax
COAL: 2.292
cci 450
A lot of TAC
3105fps SD 23.8
.750" @ 50y
Huey G2 Red dot with 3 x magnifier
Barrel is Craddock 8T 223W 10.5" Carbine Gas length with adj block.
Precision Armament Efab
I couldn't tell if it had much muzzle flash because I momentarily Blacked out from the concussion every shot.
That's an exaggeration, but It's obnoxiously loud.
Also shot some 60gr Vmax. but they didn't group as well. 1.128" at 50y still not terrible for a shorty. Both the 53 & 60's shot the tightest at the upper end of the ladder. 60 vmax were 3021fps & SD 26.8

The magnum primers didn't have any cratering, but good grief this speed is what I'd expect from 5 or 6 inches more barrel.
Per Gordon's this should be 59,868psi Also per Gordon's it shouldn't be going nearly this fast. That said Gordon's is very close with N540, N550, AA2520 in brass cases, but under estimates speed across the board for the NAS3 cases. From 10.5" - 26" doesn't matter. I
Click to expand...
Good grief what are these cases rated for?

You're running over 80,000 psi with 33.18 H20 capacity in a gun that can take 65,000 psi fairly regularly with short case life.

Probably about 34.5 grs of TAC, for a 10.5" barrel is my guess. But no one should run that in an AR 15.
Ya might get away with 32.3 with long seating of 2.292 and 2800 fps for the 53 gr.in fired cases, and this would be max magnum pressure, above the operating pressure of the 223.

Ya lose about 680 fps between 10.5 and 26" barrel...even more velocity loss as the pressure climbs to 80k and beyond.

Not all the powder is burned inside the case so barrel length definitely makes a difference in most any firearm.
 
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#634
MustangGreg66 said:
Where/How did you source the Shell Shock NAS3 cases to load? Those seem really interesting.

I'm getting similar velocity, but from a stout load of Varget in a 24" barrel. These do show some pressure signs with ejector smears and flattened edge of primers. I haven't loaded them in those cases more than once.
Projectile: 77gr SMK
Primer: Fed GMMAR
Powder: 25.2gr Varget
Case: LC '95
COAL: 2.260"
Barrel: 24" WOA
Velocity: 2885fps
SD: 11
Accuracy: ~0.6MOA
Click to expand...

I have a 24" WOA Match upper with nice irons that only has about 50 rounds down the pipe. Have been curious in finding a precise load for it. Thanks for sharing. I'll back off to mid 23.5gr and see how she does from there. I really want that upper to shoot small....They're super nice.
 
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#635
You must pay attention to case volume.
Fired, new, different brands and different designs.

Here is an example
53 gr
Same load of Tac powder.
3 different cases.
10.5" Nato chamber 2.260"
Nato case 28.xx gr H2O
New Shell shock 31.8 gr H2O
Fired Shell shock 33.1 gr H2O

So beware ...a small change in case capacity and seating depth makes a huge difference in pressure and therefore velocity.
I load lots of hybrid cases rated at 80,000 psi but do not run them that high in bolt guns...and only run them under 65,000 psi in any AR, which is the limit for magnum cartridges in bolt guns.
So becareful here, changing bullet composition, seating depth, case capacity can lead to excessive pressure in a hurry.
If these Shell Shok cases can not be reloaded you must use the pre fired case capacity for your loads like 31.8 gr of H2O has been reported...but you must weigh the capacity of the cases, if you're going to increase powder charge above reloading manuals recommendations, with your extra capacity cases.
 

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#637
Some of my recent 73gr ELDM trys with NAS3. I'll try to post pics of the groups when I log in on my phone in a minute.


Projectile: 73gr ELDM
Primer: CCI 450
Powder: 28gr AA2520
Case: Shell Shock Tech NAS3
COAL: 2.245"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2993fps
SD: 17.5
Accuracy: .73moa for 5 shots

Projectile: 73gr ELDM
Primer: CCI 450
Powder: 24.5gr N135
Case: Shell Shock Tech NAS3
COAL: 2.245"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2821fps
SD: 17.2
Accuracy: 1.59moa for 10 shots

Projectile: 73gr ELDM
Primer: CCI 450
Powder: 25.0gr N135
Case: Shell Shock Tech NAS3
COAL: 2.245"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2888fps
SD: 13.3
Accuracy: 1.11moa for 10 shots

Projectile: 73gr ELDM
Primer: CCI 450
Powder: 25.5gr N135
Case: Shell Shock Tech NAS3
COAL: 2.245"
Barrel: 18" Centurion Mk12
Suppressor: Surefire SOCOM RC2
Optic: Burris XTR Pro 5.5-30x56 Tremor 5
Velocity: 2917fps
SD: 17.3
Accuracy: 1.9moa for 10 shots

I'm going to revisit the 25.0gr N135 load and also try 26.0gr N135 next time.
 

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#638
WeR0206 said:
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.
Click to expand...
This is what I’ve settled on. 24.1 grains of N140 under 77 SMK in Lake City cases shot extremely well. I need to chrono it. I load up 77 grain SMK “seconds” with 23.8 grains of TAC in bulk cases for blasting ammo. Haven’t chrono’d those yet either. I will shortly.
 
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