conditionzero
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Fren
I did some testing this morning to try and shrink my groups. I will prefice this with, I don't think my groups at 100y are bad, they are 1/2" MOA or better. But... I like to see where the limit is. Anyways, seating depth is one way your can tune barrel harmonics if your ES/SD (combustion) is good, but your groups are "bad". Another way is a barrel tuner, as some here have done. I thought it would be cool to show this on "paper (targets)" as a way to visualize it.
Here is my control group, this is a known good load. I have confirmed this at 1000y.
Here is the next depth I tested, 2.20" CBTO. I did this on accident, I was wanting to go to 2.2010". This had my barrel SWANGIN'.
Next I tested up to 2.2020". Not as bad, but you can see it starting to tighten up as I get back to the known good load depth.
Finally I hucked a few at 2.2030". I had a pretty large drop in FPS on that 5th shot. I am learning that StaBall is... not very... stable at low temps. It was about 30F when we were shooting. If I bring that shot up 10 FPS in to the average range things get nice on the SD side (8.1 if my excel math is right) and if I omit it from the group the size gets real nice! I know... CHEATER.
Anyways I had some fun today, I am going to switch my main recipe to 2.2030" inches for now. I am maxed out on mag fed length. I am going to try some AI mags hopefully soon and see if I can push them a little more. So if you have great ES/SD and are struggling with group size, and do not / can't use a barrel tuner, start to play with your seating depth.
Here is my control group, this is a known good load. I have confirmed this at 1000y.
COAL | CBTO | Powder Charge | Projectile |
---|---|---|---|
2.8750" | 2.2040" | 42.3gn StaBall 6.5 | Berger VLD 140gn |
Here is the next depth I tested, 2.20" CBTO. I did this on accident, I was wanting to go to 2.2010". This had my barrel SWANGIN'.
COAL | CBTO | Powder Charge | Projectile |
---|---|---|---|
2.8710" | 2.20" | 42.3gn StaBall 6.5 | Berger VLD 140gn |
Next I tested up to 2.2020". Not as bad, but you can see it starting to tighten up as I get back to the known good load depth.
COAL | CBTO | Powder Charge | Projectile |
---|---|---|---|
2.8730" | 2.2020" | 42.3gn StaBall 6.5 | Berger VLD 140gn |
Finally I hucked a few at 2.2030". I had a pretty large drop in FPS on that 5th shot. I am learning that StaBall is... not very... stable at low temps. It was about 30F when we were shooting. If I bring that shot up 10 FPS in to the average range things get nice on the SD side (8.1 if my excel math is right) and if I omit it from the group the size gets real nice! I know... CHEATER.
COAL | CBTO | Powder Charge | Projectile |
---|---|---|---|
2.8740" | 2.2030" | 42.3gn StaBall 6.5 | Berger VLD 140gn |
Anyways I had some fun today, I am going to switch my main recipe to 2.2030" inches for now. I am maxed out on mag fed length. I am going to try some AI mags hopefully soon and see if I can push them a little more. So if you have great ES/SD and are struggling with group size, and do not / can't use a barrel tuner, start to play with your seating depth.