308 reloading question(s)

[cgseanp1]

Morning!

Was going through my Hornady reloading manual looking at 308 loads, and I noticed they don't list a load for WIN748 and 168/175gr bullets.

They do list loads for 150gr and they list loads for 190, but no 168 or 175.

Now, when I looked at 308 Service rifle in the same Hornady manual, they do list loads for the 168gr and WIN748.

It is my basic understanding that the 308 Service Rifle is a lighter load than regular 308. Why would Hornady not list the same load for the 308?

Also, my Sierra manual does list a load for 168gr and WIN748... it's very similar to the Hornady 308 Service rifle load..

Just trying to make sense of it all! Thanks!

PS. WIN748 is all I have currently, I think I will be swapping powder when it is time for something new.

[Divernhunter]

I think you will find the Win748 is one of the best for the 308win and also 223(using 55gr bullets).
You might try looking at the Hodgdon website for load data.

IF you are looking to load a Barnes bullet do not use data other than Barnes from their website or manual. The exception is the Hodgdon website sometimes lists loads for the Barnes bullets. The TTSX and TSX data is interchangeable.

[cgseanp1]

Thanks for reply..

I have one question I meant to ask in my original post:
Since the manual lists a load for 308 service rifle using W748 and Hornady 168 BTHP, is there any reason this could not be used for a bolt action or AR10?

[the_tunaman]

Each of the books have differing data, so I’ve found it helpful to check as many as possible when starting out. Also, with the advent of the Internet, load data from reputable sources is very simple to look up, as opposed to the old days where you really had to buy several books to reference.

[the_tunaman]

Others will chime in I’m sure, but IMHO the answer would be “it depends”. The AR platform is a gas gun, so it needs sufficient pressure to cycle the action properly.

Bolt platforms have no such limitation, and as long as the pressure is sufficient to expel the projectile you can typically get away with lighter loads.

You’d likely have to load a few up and see whether they operate your weapon properly - I’d suggest loading a single round manually and fire it off, then proceed or not depending on how it behaved.

[ar15barrels]

Here is a quickload simulation of the 168gr Hornady BTHP part# 30501 over winchester 748:

Cartridge          : .308 Win. (SAAMI)
Bullet             : .308, 168, Hornady BTHP Natl M 30501
Useable Case Capaci: 48.247 grain H2O = 3.133 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Winchester 748

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.444% 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

-04.4   90    43.00   2656    2632   50587   7212     99.6    1.219
-04.0   90    43.20   2667    2654   51319   7231     99.7    1.212
-03.6   91    43.40   2678    2676   52063   7250     99.7    1.204
-03.1   91    43.60   2689    2698   52817   7268     99.8    1.197  ! Near Maximum !
-02.7   92    43.80   2701    2720   53580   7286     99.8    1.189  ! Near Maximum !
-02.2   92    44.00   2712    2743   54354   7302     99.9    1.182  ! Near Maximum !
-01.8   92    44.20   2723    2765   55139   7319     99.9    1.175  ! Near Maximum !
-01.3   93    44.40   2734    2788   55933   7334     99.9    1.168  ! Near Maximum !
-00.9   93    44.60   2745    2810   56738   7349    100.0    1.161  ! Near Maximum !
-00.4   94    44.80   2756    2833   57555   7364    100.0    1.154  ! Near Maximum !
+00.0   94    45.00   2767    2855   58384   7377    100.0    1.147  ! Near Maximum !
+00.4   94    45.20   2778    2878   59225   7391    100.0    1.140  ! Near Maximum !
+00.9   95    45.40   2788    2900   60078   7403    100.0    1.133  ! Near Maximum !
+01.3   95    45.60   2799    2923   60945   7415    100.0    1.126  ! Near Maximum !
+01.8   96    45.80   2810    2946   61824   7427    100.0    1.120  !DANGEROUS LOAD-DO NOT USE!
+02.2   96    46.00   2821    2969   62717   7438    100.0    1.113  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 3% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 3% relative to nominal value:
+Ba     94    45.00   2800    2925   61885   7264    100.0    1.122  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 3% relative to nominal value:
-Ba     94    45.00   2728    2777   54878   7467     99.7    1.174  ! Near Maximum !

7.62x51 rifles are usually expecting to keep pressures under 55,000PSI while 308 rifles can go to just over 60,000PSI.
Most 308 rifles should function with 55,000 PSI loads without problems.

[QED]

The Berger reloading manual has 748 load data for 168 and 175 gr bullets. Bolt actions tend to be able to make safe use of higher pressure loads than semi-auto actions but in either case, work up to the max load from a sane starting point.

[divingin]

To answer your original question, manufacturers don't list every bullet/powder combination that works. They generally choose a representative sampling of popular powders that work well (and occasionally not so well.)

Kind of highlights the need for multiple information sources, and the need to use them.