Another turkey day at the range….. Oct 14, 2015 12:58:30 GMT -5
Post by Richard on Oct 14, 2015 12:58:30 GMT -5
A great day to be at the range with Herman and Bill……………60* and clear with no wind.
This first group is particularly noteworthy as I have been experiencing this cycle for a number of years now. Not every time but enough to lead me to believe there is something to it. It involves cold barrel velocities and grouping and a shift to a different POI when warming? If you follow my velocity readings and where the shots grouped you will see what I mean. Let me say this…………The hold in right on, the scope is 32X NF and the trigger is 2 oz. Shilen. It only fires when I “touch it!”
Starting with the cold clean barrel:
The first three shots averaged 2857 fps with a 16 fps ES. They grouped nicely in .510” ½” high and ½” right. The barrel is now starting to warm (not hot, just warm) Shots #4 now drops to 2828 fps……………..shot #5 comes out at 2832 fps and are in one hole but an inch higher?................I was now intending to fire a sixth shot to see if it also went into the same hole?.............But, we were interrupted by a flock of turkeys walking about 50 yards out in front of us!
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As we killed some 10 minutes, the barrel had a chance to cool back down to ambient temperature but I still decided to fire the 6th. shot. Note: the velocity went up to 2843 and impacted the top of the first three shot group. It left the second group at .339” which was also good. But, it seemed that the slight rise in velocity over shots 4 & 5 caused it to drop a little . Had this been the first time it happened, I would have just shrugged my shoulders and said: “Oh well?” But I have seen this very similar thing happen numerous times in the past…………Thoughts?
If you look at the average velocity for all ten shots you will see it was 2861 with an ES of 58 fps. If you then eliminate the first cooler barrel shot (2895) the ES for the remaining nine shots is only 31 fps.
Getting more used to using the “come ups” on the NF, I dialed up and using a similar load (10/60 vs. 10/59) , put two (1 & 2)shots on the steel gong at 300 yards. I then went to the bullseye and found my elevation almost right but the POI a little to the right. (shot #3). Adjusted the scope a little more left and put seven shots down range. Best five out of the seven in just under two inches. (made another scope adjustment)
For the third group I switched to the 250 TEZ with the same 10/60 duplex. Not a one holer but five sub MOA is plenty deer good. Based on the low, 18 fps, ES, I would have thought the group would have been a little better? Maybe some slight wind picking up which I did not see………..Bill thought he was seeing some activity on the grass.
Another scope adjustment…………
The last group was shot with the same load as #3. Here, I had 10 fps ES for six shots. The best five out of six was 2.6”, much similar to group #3.
And that is it! No earth shaking results, just what I found with my gun and loads on this date.