Re: Grouping at different ranges
Well, there could be a book written about such things easily, pretty broad topic to cover all the whys and hows.
That said, lets simplify things.
In long range shooting, generally the bullets used are long, heavy for caliber bullets driven through fast twist barrels. As such, it takes a certain amount of time for the bullet to actually shed the effects of the rifling as it leaves the muzzle and fly true to its own center of cravity. The longer, the heavier, the faster the velocity and the higher the rotational velocity, the farther this distance is before the bullet "goes to sleep".
As such, it is not uncommon to see a long range rifle shoot in the 3/4" range at 100 yards only to shoot the same group size at 200 and at times 300 yards. This is why for long range shooting, if you are not testing your loads at 200 or 300 yards minimum, there is a good likelyhood that you are passing over some very good long range combinations.
On the other side of the coin, a load can cut very tight groups at close range but fall apart at longer ranges. This can be caused by several things. Could be that the bullet is only marginally stabilized. Could be that the bullet itself is not quality and the imperfections on the bullet or the load itself are magnified as the range increases.
This is generally seen more with conventional weight or light weight bullets. Again, its always best to test your loads at longer ranges to confirm if they are actually bad or good loads.
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