Am I thinking right? Load development for .243 on 105 hybrids and 107 SMKs. Would it be fair to say that a five shot group, with all things considered, that has an ES =16fps and a vertical spread of .250" but overall group size of .600" is now a prime candidate for playing with the seating depth? Is horizontal spread related to seating depth more so than charge? Is vertical spread more so related to charge than seating depth? I've been playing with imr and H 4350 for these loads. Hawk Hill 8 twist on Savage action, Lapua brass, cci primers and whidden dies. .002" neck tension. Not getting the ES numbers I would like but think I'm getting close. Some of the worst groups I have had have had the lowest ES numbers...what gives? Educate me please.
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Vertical Spread vs Horizontal Spread
- Thread starter Ghost7
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Mikecr
Well-Known Member
You could have done seating testing before powder, which would likely have helped with powder/charge choice.
You can do seating testing now, but keep in mind that adjusting seating will probably affect your powder results so far, causing 2 different swings at once, making it harder to identify best seating in it's own.
This is the reason most people conclude with seating adjustments that whatever seating they chose to begin (for powder testing), that is, whatever they pulled out of their butts, must have been the best(everything else seems no better and worse). So they end up adjusting seating right back where it was..
You'll notice with Berger's full seating testing (which is excellent) they recommend backing off the charge. This is not just for pressure concerns when touching lands, but also to steer clear of any powder nodes (which seating adjustments might take you in & out of).
You can do seating testing now, but keep in mind that adjusting seating will probably affect your powder results so far, causing 2 different swings at once, making it harder to identify best seating in it's own.
This is the reason most people conclude with seating adjustments that whatever seating they chose to begin (for powder testing), that is, whatever they pulled out of their butts, must have been the best(everything else seems no better and worse). So they end up adjusting seating right back where it was..
You'll notice with Berger's full seating testing (which is excellent) they recommend backing off the charge. This is not just for pressure concerns when touching lands, but also to steer clear of any powder nodes (which seating adjustments might take you in & out of).
Mike is correct. There are no specific answers, but generally horizontal is either wind or concentricity of the bullet; vertical is sometimes the powder charge, or seating depth. You need to try each change just one at a time. Run your charge up or down .2 grs. at a time. Change seating depth by .005" at a time. Use good dies that create straight seating.
Canadian Bushman
Well-Known Member
The only times ive seen a rifle shoot small vertical and large horizontal was because wind or gun handling.
There was a very knowledgeable guy from Australia, can't remember his name, that said this:
"Large Triangle, seat out to increase OAL
2 together and the 3rd away from the group, shorten OAL"
I have read vertical is often related to pressure/velocity variations and horizontal is often related to bedding.
"Large Triangle, seat out to increase OAL
2 together and the 3rd away from the group, shorten OAL"
I have read vertical is often related to pressure/velocity variations and horizontal is often related to bedding.
