What the heck is going on here?
I am experiencing this phenomena with my new .223 Wylde AR-15 build, but also to an extent with my other two AR’s. Shown below are five 5-shot groups shot today at 100 yards. (Ammo used includes 69gr. and 77gr. SMK handloads, shot from a bench with a bipod and a rear bag through a 30X scope.) What I am seeing, virtually every time, is that the first shot from a magazine, where the first round is fed by closing the bolt, has a point of impact about a full inch higher than the next four shots which are fed by bolt cycling upon firing, which form a nice group ~1” below the initial shot. The first three targets show this. The next two targets were shot by holding an aiming point an inch below the center of the target for the first shot, then holding on center for the next four shots.
Targets with the first shot aiming point 1” low
This is not a case of cold bore POI change as the rifle these groups are shot when the rifle is fully “warmed-up”. It also has nothing to do with my hold – I’m an experienced enough shooter to know my rifle holds are pretty much equivalent on all shots. It seems to be something to do with how the round is seated(???): start of a mag from the open bolt position vs. bolt cycling by firing.
Two questions.
1) What is causing this?
2) How can this be eliminated?
I am wondering if over or under gassing can cause this? As I use a brass catcher to catch my cases I can’t really say what clock direction the cases would go without the gas catcher. Note that these are NOT hot loads. Any insight into this would be appreciated.
I am experiencing this phenomena with my new .223 Wylde AR-15 build, but also to an extent with my other two AR’s. Shown below are five 5-shot groups shot today at 100 yards. (Ammo used includes 69gr. and 77gr. SMK handloads, shot from a bench with a bipod and a rear bag through a 30X scope.) What I am seeing, virtually every time, is that the first shot from a magazine, where the first round is fed by closing the bolt, has a point of impact about a full inch higher than the next four shots which are fed by bolt cycling upon firing, which form a nice group ~1” below the initial shot. The first three targets show this. The next two targets were shot by holding an aiming point an inch below the center of the target for the first shot, then holding on center for the next four shots.
Targets with the first shot aiming point 1” low
This is not a case of cold bore POI change as the rifle these groups are shot when the rifle is fully “warmed-up”. It also has nothing to do with my hold – I’m an experienced enough shooter to know my rifle holds are pretty much equivalent on all shots. It seems to be something to do with how the round is seated(???): start of a mag from the open bolt position vs. bolt cycling by firing.
Two questions.
1) What is causing this?
2) How can this be eliminated?
I am wondering if over or under gassing can cause this? As I use a brass catcher to catch my cases I can’t really say what clock direction the cases would go without the gas catcher. Note that these are NOT hot loads. Any insight into this would be appreciated.
