I have to be honest, I have never tried Viht powders due to the extra cost. After being forced to buy some and try (N135) due to a severe powder shortage around here and working with it a bit with the 155's in the 308 I was completely impressed with its low ES and excellent accuracy, I decided to donate more $$ to Viht and try a slower version (N540) for the heavier bullets (178-200's) I took it home and loaded up some 178's in the form of a ladder test. After fouling one shot from a clean barrel I set up over the chrony and took aim. After the trigger broke, my first reaction was that the rifle didnt hit me as hard as normal. Next I looked at the chrony and to my suprise it read 2750. I cringed as I prepared to lift the bolt but to my suprise the bolt lift was 100% smooth and easy. A primer and case base check revealed a mild load. I fired the next two with identical results AND shot them into a sub .5 MOA group. I was convinced that due to the lack of recoil, lack of pressure signs and high velocity and excellent accuracy (155's had done the best overall) that I had accidentaly grabbed 155 AMAX's instead of 178's. I pulled one bullet from another charge with a set of pliers. It was indeed 178's AND NOT 155's. To say the least I was suprised. I fired the next group .5 grain up and the same results applied. Good accuracy, higher velocity and mild load charachteristics. I took the 178 all the way to 2850 and stopped there. At 2850 there was an ever so slight click at the top of the bolt cycle and a teeny tiny bit of cratering on the pin indent. The accuracy here was 7/8" at 300 yards. I have been back to the range 3 more times since with the 2750 FPS load with identical results. Same velocity, near identical accuracy and no pressure signs. The best group was 1.00" and the worst was 1.25" at 300. All I can say is N540 has totally impressed me.
I erased the charge weights. Sorry! Please, if you try some loads start low and work up as I did and STOP at the frist sign of pressure. I will say that the charge weights used here are NOT abnormal.
Higher charges from session #1: