No need to waste the primer. Pull the primer punch out of the sizing die first, then size away. Primers saved.
After cutting the powder charge in half and (from feel of recoil) reducing it to next to nothing
That is very disturbing. Powder charges are typically measured in tenths (0.10) of a grain, from a minimum (and Not Below) charge to a maximum (Not to Exceed) charge - to stay within the SAFE pressure regime for your barrel (and not blow yourself up). A charge that is too small is potentially as dangerous as one that is too large.
For .308 cal. x 168 grain bullets (probably similar for the SMK bullets), loads from
http://data.hodgdon.com/cartridge_load.asp are listed below
[NOTE: None of the minimum loads below is 1/2 or 50%, whichever is less, of the maximum load]:
Bullet Weight (Gr.)............Mfg Powder.............Bullet Dia..C.O.L......Grs....Vel. (ft/s).....Pressure......Grs......Vel. (ft/s).....Pressure
168 GR. BAR TTSX BT Hodgdon CFE 223 .308" 2.800" 41.0 2444 39,600 PSI 45.0C 2664 49,800 PSI
168 GR. BAR TTSX BT Hodgdon Varget .308 2.800" 41.0 2514 46,100 PSI 45.0C 2737 60,000 PSI
168 GR. BAR TTSX BT IMR IMR 4320 .308" 2.800" 42.0 2490 47,200 PSI 45.5C 2715 60,700 PSI
168 GR. BAR TTSX BT IMR IMR 4064 .308" 2.800" 43.0 2539 47,400 PSI 45.0C 2743 58,900 PSI
168 GR. BAR TTSX BT Hodgdon BL-C(2) .308" 2.800" 43.0 2532 46,000 PSI 46.0 2697 55,000 PSI
168 GR. BAR TTSX BT IMR IMR 4895 .308" 2.800" 41.0 2514 47,400 PSI 44.0C 2692 57,800 PSI
168 GR. BAR TTSX BT Hodgdon H335 .308" 2.800" 39.0 2500 46,800 PSI 42.0 2661 56,100 PSI
168 GR. BAR TTSX BT Hodgdon H4895 .308" 2.800" 39.0 2497 45,100 PSI 43.0C 2727 59,900 PSI
168 GR. BAR TTSX BT IMR IMR 8208 XBR .308" 2.800" 39.0 2505 46,500 PSI 43.0C 2724 60,700 PSI
168 GR. BAR TTSX BT IMR IMR 3031 .308" 2.800" 38.0 2493 46,600 PSI 41.5C 2693 58,600 PSI
168 GR. BAR TTSX BT Hodgdon Benchmark .308" 2.800" 38.0 2458 44,500 PSI 42.0C 2686 59,500 PSI
168 GR. SIE HPBT IMR IMR 4007 SSC .308" 2.800" 43.2 2466 44,300 PSI 48.0C 2729 58,300 PSI
168 GR. SIE HPBT Hodgdon CFE 223 .308" 2.800" 46.6 2662 48,200 PSI 49.0 2828 60,400 PSI
168 GR. SIE HPBT Hodgdon Varget .308" 2.800" 42.0 2520 41,200 CUP 46.0C 2731 50,600 CUP
168 GR. SIE HPBT IMR IMR 4320 .308" 2.800" 41.5 2463 43,800 PSI 46.0 2733 59,300 PSI
168 GR. SIE HPBT IMR IMR 4064 .308" 2.800" 41.5 2518 43,800 PSI 45.9C 2766 58,800 PSI
168 GR. SIE HPBT Hodgdon BL-C(2) .308" 2.800" 44.0 2569 39,400 CUP 47.0 2754 50,200 CUP
168 GR. SIE HPBT IMR IMR 4895 .308" 2.800" 41.0 2447 39,700 PSI 45.4C 2758 58,000 PSI
168 GR. SIE HPBT Hodgdon H335 .308" 2.800" 39.0 2451 37,700 CUP 42.0 2631 49,300 CUP
168 GR. SIE HPBT Hodgdon H4895 .308" 2.800" 41.0 2551 38,300 CUP 43.5 2703 49,500 CUP
168 GR. SIE HPBT IMR IMR 8208 XBR .308" 2.800" 39.0 2493 49,000 PSI 43.3 2707 61,500 PSI
168 GR. SIE HPBT IMR IMR 3031 .308" 2.800" 39.0 2507 43,900 PSI 42.0 2710 58,900 PSI
168 GR. SIE HPBT Hodgdon Benchmark .308" 2.800" 38.0 2416 38,100 CUP 42.0 2630 49,300 CUP
The absolute difference between min and max charges above range from 4.65% to 11.11%. A charge reduction of 50% or more is not recommended and mercifully for you this time, allowed the rifle to continue undamaged, a consequence that can not be counted on to prevail. Obviously, your results may vary, but it is your face, your hands, your eyes, your teeth, your mouth, your features, your brain, and your equipment that is just inches away from a pressure vessel (bomb) that could ruin your day (or life).