Lower pressure AR15 practice loads

[bigedp51]

I'm loading for three different AR15 rifles with carbine, mid-length and rifle gas systems. Do any of you have lower pressure practice loads that are reasonably accurate for practice shooting under 100 yards with 55 grain bullets. Right now I'm loading 24.7 grains of H335 with Hornady 55gr fmj at approximatly 46,000 psi.

 

[kentuckytroutbum]

biged-

I'm sure that you are already aware of the need for AR's to operate within a fairly narrow pressure range. What is important is the port pressure at the gas tube. I experimented with
reduced loads in my AR's, and I fairly quickly ran into the situation of "short stroking." The bolt would retract enough to eject the empty brass, but not far enough to pick up another round
from the magazine. Basically turned it into a single shot. Sometimes the case would not fully eject, and then I would have to dig the case out of the action. Became a PITA. Went back to my
regular loads even for practice.

If your current load is functioning the rifle, I would stay with what you have. FMJ's and Hodgdon powders are usually inexpensive to shoot.

Bill

 

[bigedp51]

biged-

I'm sure that you are already aware of the need for AR's to operate within a fairly narrow pressure range. What is important is the port pressure at the gas tube.

I know this and that is why I ask the question, because bullets and powder are hard to come by now so I'm looking to see what reloaders are using for reliable practice loads with 55 grain bullets.

Below is my 24.7 grain load that functions in my A2 HBAR and "should" function 100% in a carbine and mid-length gas system. What I'm asking is do any of you have similar or slightly lower pressure loads that function?

Cartridge : .223 Rem. (SAAMI) (52,000 cup or 55,000 psi loading data)
Bullet : .224, 55, Hornady V-MAX FB 22271-72
Useable Case Capaci: 27.380 grain H2O = 1.778 cm³
Cartridge O.A.L. L6: 2.260 inch = 57.40 mm
Barrel Length : 20.0 inch = 508.0 mm
Powder : Hodgdon H335

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 72 19.77 2400 704 24247 6397 83.3 1.240
-18.0 74 20.26 2459 739 25788 6624 84.8 1.211
-16.0 75 20.76 2519 775 27430 6848 86.2 1.182
-14.0 77 21.25 2578 812 29179 7068 87.5 1.154
-12.0 79 21.74 2638 850 31044 7283 88.8 1.126
-10.0 81 22.24 2698 889 33031 7493 90.0 1.099
-08.0 83 22.73 2758 929 35151 7696 91.2 1.073
-06.0 84 23.23 2818 970 37414 7892 92.3 1.047
-04.0 86 23.72 2878 1012 39830 8080 93.4 1.017
-02.0 88 24.22 2938 1054 42411 8259 94.4 0.989
+00.0 90 24.71 2999 1098 45168 8429 95.3 0.962
+02.0 91 25.20 3059 1143 48125 8589 96.1 0.935 ! Near Maximum !
+04.0 93 25.70 3119 1188 51288 8739 96.9 0.909 ! Near Maximum !
+06.0 95 26.19 3179 1234 54670 8877 97.6 0.884 !DANGEROUS LOAD-DO NOT USE!
+08.0 97 26.69 3238 1281 58267 9002 98.2 0.860 !DANGEROUS LOAD-DO NOT USE!
+10.0 99 27.18 3298 1328 62112 9115 98.7 0.837 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 90 24.71 3161 1220 54265 8525 99.3 0.889 ! Near Maximum !
Data for burning rate decreased by 10% relative to nominal value:
-Ba 90 24.71 2793 953 36874 7929 87.5 1.054

 

[mac86951]

You'll need to load down and test for yourself.

As mentioned above, a lower pressure practice round, we can all post our pet loads, but they may/may not functionally cycle your rifles.

If you are trying to save powder, then try a starting load of H335 and 55gr (see Hodgdon website). You might save up to 2gr of powder that way, so not really that much unless you shoot a TON. See if they cycle all of your ARs then you know. You can test this by doing 3-5 single shot experiments. Does the bolt lock back every time?

-Mac

 

[bigedp51]

You'll need to load down and test for yourself.

As mentioned above, a lower pressure practice round, we can all post our pet loads, but they may/may not functionally cycle your rifles.

I'm asking for practice rounds that do function and cycle the action.

With Quickload I can enter YOUR load and get a chamber pressure and get an idea of the lowest chamber pressures that cycle the action.

I have been reloading for over 46 years, I do not need advice on how to do it, all I want to know is what does work from all of you.

If its easier just give your pet 55 grain bullet loads, I'm looking for data.
I'm out of H335 and 748 and haven't been able to buy more.

So far at the CMP forum I have

"26.0 grains of AA2460 with a 55 grain M-193 FMJ" (46,669 psi)
"24 grs of imr4895 or varget works well for my ar's" (33,965 psi and 35977 psi)

 

[mac86951]

Sorry, I don't mean to offend. My rifle length AR functions just fine with a load of 20.5gr IMR-4895 and a Hornady 55gr FMJBT.

I'd be willing to bet you that load won't repeatedly cycle your ARs, feel free to try it out.

-Mac

 

[bigedp51]

Sorry, I don't mean to offend. My rifle length AR functions just fine with a load of 20.5gr IMR-4895 and a Hornady 55gr FMJBT.

I'd be willing to bet you that load won't repeatedly cycle your ARs, feel free to try it out.

-Mac

Quickload answer

20.5gr IMR-4895 and a Hornady 55gr FMJBT, 2397 fps, 29980 psi

Thank you

 

[mac86951]

Case volume of 29.8gr, not the QL default of 28.8

-Mac

 

[bigedp51]

Case volume of 29.8gr, not the QL default of 28.8

-Mac

Case volume of 29.8gr = 2422 fps, 31,093 psi
(My cases 30.4)