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**FLIGHT762** · 02-23-2021, 7:59 PM

42.0-43.0 Grs. of IMR 4064 is a well proven load for the M1-A with a 168 OTM.

If you feel the need, start @ 40.0 and work up.

**maxx03** · 02-23-2021, 8:01 PM

42.6 gr 4064 168 SMK LC brass gives me 2650 fps at the muzzle.

**devster55** · 02-23-2021, 8:07 PM

Thank you guys. That confirms the data range I need. I’ll work up from 42 and go from there.

**tabascoz28** · 02-23-2021, 8:16 PM

Do M1As have an op rod like M1 garands? I was told to be careful using strong loads which can damage that.

**slamfire1** · 02-23-2021, 8:32 PM

Originally posted by tabascoz28

Do M1As have an op rod like M1 garands? I was told to be careful using strong loads which can damage that.

Yes and no. The M14 operating rod is stiffer and shorter. The Garand operating rod would bend just at the upper ferrule, causing issues. The M14 operating rod will bend at the saddle if over accelerated.

Keep your loads in the lower to middle 40,000 psia range with these weapons. I learned that a proper load gave a clip/clop cycling feeling. You should be just able to perceive the action ejecting and loading. If the cycle is just one big bang, and the weapon ejects and feeds faster than human perception, than the gas pressures are too high.

**ptmn** · 02-23-2021, 8:33 PM

An M1A with IMR4064 and 168 HPBT's is a real winning combo. You should have a lot of fun punching some tight groups

**devster55** · 02-23-2021, 9:04 PM

Originally posted by ptmn

An M1A with IMR4064 and 168 HPBT's is a real winning combo. You should have a lot of fun punching some tight groups

**ar15barrels** · 02-24-2021, 12:20 AM

Originally posted by FLIGHT762

42.0-43.0 Grs. of IMR 4064 is a well proven load for the M1-A with a 168 OTM.

Originally posted by maxx03

42.6 gr 4064 168 SMK LC brass gives me 2650 fps at the muzzle.

I recommend measuring the case capacity of a fired case from your actual rifle in grains of water.
Quickload uses 52gr for the 7.62x51 model while they have 56gr for the 308 model.
Playing with only case capacity to match up maxx03's chrono data, I came to 52.6 grains of case capacity.

Using that, here is what Quickload says for a prediction with the selected components:

Code:

Cartridge          : .308 Win. (SAAMI)
Bullet             : .308, 168, Sierra HPBT MatchK 2200
Useable Case Capaci: 45.322 grain H2O = 2.943 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : IMR 4064

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.476% 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

-04.8  101    40.00   2495    2322   49333   7342     96.4    1.180
-04.3  102    40.20   2507    2344   50081   7376     96.6    1.172
-03.8  102    40.40   2519    2367   50840   7409     96.7    1.164
-03.3  103    40.60   2531    2389   51612   7441     96.9    1.156
-02.9  103    40.80   2543    2412   52396   7473     97.1    1.149
-02.4  104    41.00   2555    2434   53192   7504     97.2    1.141  ! Near Maximum !
-01.9  104    41.20   2567    2457   54001   7535     97.3    1.133  ! Near Maximum !
-01.4  105    41.40   2578    2480   54823   7566     97.5    1.126  ! Near Maximum !
-01.0  105    41.60   2590    2503   55659   7596     97.6    1.118  ! Near Maximum !
-00.5  106    41.80   2602    2526   56508   7625     97.8    1.111  ! Near Maximum !
+00.0  106    42.00   2614    2549   57370   7654     97.9    1.104  ! Near Maximum !
+00.5  107    42.20   2626    2573   58247   7682     98.0    1.097  ! Near Maximum !
+01.0  107    42.40   2638    2596   59138   7709     98.1    1.089  ! Near Maximum !
+01.4  108    42.60   2650    2619   60044   7737     98.3    1.082  ! Near Maximum !
+01.9  108    42.80   2662    2643   60964   7763     98.4    1.075  ! Near Maximum !
+02.4  109    43.00   2674    2667   61900   7789     98.5    1.068  !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    106    42.00   2726    2772   67871   7511    100.0    1.031  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    106    42.00   2464    2265   47204   7445     92.1    1.199

**smoothy8500** · 02-24-2021, 9:03 AM

No need to go beyond 41.5gr of IMR4064 with 168's in LC brass. Start at 40.0 and use 0.5gr increments. You will have the performance and accuracy needed for 600yds.

**devster55** · 02-24-2021, 10:55 AM

Originally posted by ar15barrels

I recommend measuring the case capacity of a fired case from your actual rifle in grains of water.
Quickload uses 52gr for the 7.62x51 model while they have 56gr for the 308 model.
Playing with only case capacity to match up maxx03's chrono data, I came to 52.6 grains of case capacity.

Using that, here is what Quickload says for a prediction with the selected components:

Code:

Cartridge          : .308 Win. (SAAMI)
Bullet             : .308, 168, Sierra HPBT MatchK 2200
Useable Case Capaci: 45.322 grain H2O = 2.943 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : IMR 4064

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.476% 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

-04.8  101    40.00   2495    2322   49333   7342     96.4    1.180
-04.3  102    40.20   2507    2344   50081   7376     96.6    1.172
-03.8  102    40.40   2519    2367   50840   7409     96.7    1.164
-03.3  103    40.60   2531    2389   51612   7441     96.9    1.156
-02.9  103    40.80   2543    2412   52396   7473     97.1    1.149
-02.4  104    41.00   2555    2434   53192   7504     97.2    1.141  ! Near Maximum !
-01.9  104    41.20   2567    2457   54001   7535     97.3    1.133  ! Near Maximum !
-01.4  105    41.40   2578    2480   54823   7566     97.5    1.126  ! Near Maximum !
-01.0  105    41.60   2590    2503   55659   7596     97.6    1.118  ! Near Maximum !
-00.5  106    41.80   2602    2526   56508   7625     97.8    1.111  ! Near Maximum !
+00.0  106    42.00   2614    2549   57370   7654     97.9    1.104  ! Near Maximum !
+00.5  107    42.20   2626    2573   58247   7682     98.0    1.097  ! Near Maximum !
+01.0  107    42.40   2638    2596   59138   7709     98.1    1.089  ! Near Maximum !
+01.4  108    42.60   2650    2619   60044   7737     98.3    1.082  ! Near Maximum !
+01.9  108    42.80   2662    2643   60964   7763     98.4    1.075  ! Near Maximum !
+02.4  109    43.00   2674    2667   61900   7789     98.5    1.068  !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    106    42.00   2726    2772   67871   7511    100.0    1.031  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    106    42.00   2464    2265   47204   7445     92.1    1.199

**devster55** · 02-24-2021, 6:16 PM

Originally posted by ar15barrels

I recommend measuring the case capacity of a fired case from your actual rifle in grains of water.
Quickload uses 52gr for the 7.62x51 model while they have 56gr for the 308 model.
Playing with only case capacity to match up maxx03's chrono data, I came to 52.6 grains of case capacity.

Using that, here is what Quickload says for a prediction with the selected components:

Code:

Cartridge          : .308 Win. (SAAMI)
Bullet             : .308, 168, Sierra HPBT MatchK 2200
Useable Case Capaci: 45.322 grain H2O = 2.943 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : IMR 4064

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.476% 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

-04.8  101    40.00   2495    2322   49333   7342     96.4    1.180
-04.3  102    40.20   2507    2344   50081   7376     96.6    1.172
-03.8  102    40.40   2519    2367   50840   7409     96.7    1.164
-03.3  103    40.60   2531    2389   51612   7441     96.9    1.156
-02.9  103    40.80   2543    2412   52396   7473     97.1    1.149
-02.4  104    41.00   2555    2434   53192   7504     97.2    1.141  ! Near Maximum !
-01.9  104    41.20   2567    2457   54001   7535     97.3    1.133  ! Near Maximum !
-01.4  105    41.40   2578    2480   54823   7566     97.5    1.126  ! Near Maximum !
-01.0  105    41.60   2590    2503   55659   7596     97.6    1.118  ! Near Maximum !
-00.5  106    41.80   2602    2526   56508   7625     97.8    1.111  ! Near Maximum !
+00.0  106    42.00   2614    2549   57370   7654     97.9    1.104  ! Near Maximum !
+00.5  107    42.20   2626    2573   58247   7682     98.0    1.097  ! Near Maximum !
+01.0  107    42.40   2638    2596   59138   7709     98.1    1.089  ! Near Maximum !
+01.4  108    42.60   2650    2619   60044   7737     98.3    1.082  ! Near Maximum !
+01.9  108    42.80   2662    2643   60964   7763     98.4    1.075  ! Near Maximum !
+02.4  109    43.00   2674    2667   61900   7789     98.5    1.068  !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    106    42.00   2726    2772   67871   7511    100.0    1.031  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    106    42.00   2464    2265   47204   7445     92.1    1.199

The case I weighed had 54.5gr of capacity.

**ar15barrels** · 02-24-2021, 9:54 PM

Originally posted by devster55

The case I weighed had 54.5gr of capacity.

Chrono loads as you work up.
The velocity should closely equate to pressure regardless of if the velocity matches the predicted charge.

So, if you are trying 42.0gr but getting 2508fps, your pressure is more like 54,149psi than it is like the 52,607psi shown for 42gr.

Code:

Cartridge          : .308 Win. (SAAMI)
Bullet             : .308, 168, Sierra HPBT MatchK 2200
Useable Case Capaci: 47.222 grain H2O = 3.066 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : IMR 4064

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.463% 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

-04.6  100    41.20   2523    2375   49647   7590     96.9    1.176
-04.2  101    41.40   2535    2397   50369   7622     97.0    1.168
-03.7  101    41.60   2547    2419   51103   7655     97.2    1.161
-03.2  102    41.80   2558    2441   51847   7687     97.3    1.154
-02.8  102    42.00   2570    2463   52603   7718     97.5    1.146
-02.3  103    42.20   2581    2486   53370   7749     97.6    1.139  ! Near Maximum !
-01.9  103    42.40   2593    2508   54149   7779     97.7    1.132  ! Near Maximum !
-01.4  104    42.60   2605    2531   54940   7809     97.9    1.124  ! Near Maximum !
-00.9  104    42.80   2616    2553   55742   7838     98.0    1.117  ! Near Maximum !
-00.5  105    43.00   2628    2576   56557   7866     98.1    1.110  ! Near Maximum !
+00.0  105    43.20   2639    2598   57385   7895     98.2    1.103  ! Near Maximum !
+00.5  106    43.40   2651    2621   58225   7922     98.3    1.096  ! Near Maximum !
+00.9  106    43.60   2662    2644   59079   7949     98.4    1.089  ! Near Maximum !
+01.4  107    43.80   2674    2667   59946   7976     98.6    1.082  ! Near Maximum !
+01.9  107    44.00   2685    2690   60826   8002     98.7    1.075  ! Near Maximum !
+02.3  107    44.20   2697    2713   61720   8027     98.8    1.069  !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    105    43.20   2750    2820   67760   7722    100.0    1.031  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    105    43.20   2490    2313   47339   7704     92.7    1.198

**devster55** · 02-24-2021, 11:36 PM

Originally posted by ar15barrels

Chrono loads as you work up.
The velocity should closely equate to pressure regardless of if the velocity matches the predicted charge.

So, if you are trying 42.0gr but getting 2508fps, your pressure is more like 54,149psi than it is like the 52,607psi shown for 42gr.

Code:

Cartridge          : .308 Win. (SAAMI)
Bullet             : .308, 168, Sierra HPBT MatchK 2200
Useable Case Capaci: 47.222 grain H2O = 3.066 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : IMR 4064

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.463% 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

-04.6  100    41.20   2523    2375   49647   7590     96.9    1.176
-04.2  101    41.40   2535    2397   50369   7622     97.0    1.168
-03.7  101    41.60   2547    2419   51103   7655     97.2    1.161
-03.2  102    41.80   2558    2441   51847   7687     97.3    1.154
-02.8  102    42.00   2570    2463   52603   7718     97.5    1.146
-02.3  103    42.20   2581    2486   53370   7749     97.6    1.139  ! Near Maximum !
-01.9  103    42.40   2593    2508   54149   7779     97.7    1.132  ! Near Maximum !
-01.4  104    42.60   2605    2531   54940   7809     97.9    1.124  ! Near Maximum !
-00.9  104    42.80   2616    2553   55742   7838     98.0    1.117  ! Near Maximum !
-00.5  105    43.00   2628    2576   56557   7866     98.1    1.110  ! Near Maximum !
+00.0  105    43.20   2639    2598   57385   7895     98.2    1.103  ! Near Maximum !
+00.5  106    43.40   2651    2621   58225   7922     98.3    1.096  ! Near Maximum !
+00.9  106    43.60   2662    2644   59079   7949     98.4    1.089  ! Near Maximum !
+01.4  107    43.80   2674    2667   59946   7976     98.6    1.082  ! Near Maximum !
+01.9  107    44.00   2685    2690   60826   8002     98.7    1.075  ! Near Maximum !
+02.3  107    44.20   2697    2713   61720   8027     98.8    1.069  !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    105    43.20   2750    2820   67760   7722    100.0    1.031  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    105    43.20   2490    2313   47339   7704     92.7    1.198

**Sailormilan2** · 02-25-2021, 5:33 AM

The US Military Mk316 load, which is the load for 1000 yds, is 175 gr bullet with 41.7 gr of IMR4064, loaded to 2.81+". So, as was mentioned, 41.5 with a 168 gr bullet will be fine. Load to about 2.815". The Mk316 load is probably a little hotter than it needs to be for most shooting.

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