Up to now almost all of my shooting with the 77gn bullet has been at 100 to 300yd. Previously I have shot the 69gn SMK at 600 and had close to MOA groups but have not been able to break into the sub MOA at that range. Not bad but not great.

I have had two sessions now shooting the 77SMK at 600yd. I have been comparing IMR4166 (21.5gn) and Varget (23.5gn). There is about 100fps difference in muzzle velocity according to book load data. OAL for both is 2.28" They are very close in group sizes at 100yd with the 4166 being a little better by about 0.1" on average (my lack of shooting skill makes this small a difference kind of a wash). FYI I am shooting an Axis HB, 22" barrel in .223 with Boyd's Pro Varmint stock and Vortex 4-16 Diamonback scope. It is not pillar or glass bedded, just bolted into the stock. Shooting is from an inexpensive Caldwell bench rest with a bag at the rear, and a mediocre shooter

The first session was with 4166. At 600yd 5rounds went into 7". No wind at all on that day. At 100yd that same day I had two 5rnd groups of 0.4" and 0.6". Group size at 600 was such that it made me wonder if the bullets were stable. I figured it should be well under MOA.

Today I had the Varget load set up at 100, 400, 500 and 600yd. Wind started light then went to a little gusty, 6-9mph at 45deg to the bullet path. At 400yd and light wind 4 rnds went into a 1.8" group. At 500 yd and light wind 5rnds went into a 3.5" group. At 600yd the wind had picked up. I held off by 6" to account for the wind. The horizontal group size was 5.2". The vertical group size was 2.7". At 100yd with the gusty wind I had three 5rnd groups of 0.4, 0.8 and 0.9".

I was not trying to figure out the gusts of wind. At our range it may be a low point in the turbulence at the bench but the wind flags show significant wind ast range. I set my wind hold at a 'median' point and shoot a string, without waiting for a 'calm' point. I know this is not a good technique but I am a relative novice to wind doping at medium and longer range.

So, for me at least, I will venture a guess that the 77gn bullet is stabilized out to 600yd. Is it stable further out? According to theory it should be stable as long as it is supersonic, which for this load is just beyond 1000yd. I will shoot it at 1000 just for grins but that is not my goal. My goal is to have an accurate shooter at 600yd and so far the 77 SMK's are working the best.