Group shape and relationship of bullet to rifling

[Silvertp]

Read on a thread somewhere here on GBO that there is a relationship between the group shape and the need to either shorten or lengthen the COL. 

Went something like...if it puts shots in a triangle shape you need to move the bullet closer to the lands.  If your gun puts two shots together and one outside the group (or two groups seperated) then you need to shorten the OAL.

Is it really that simple?

Does anyone here have a rule of thumb for deciding if a reload would benefit from moving the bullet closer or further from the lands??

Silvertp

[Graybeard]

Somebody is pulling your leg.

Two touching and one wide is more often a bedding issue or a bad load with wide variance in velocity. An equalateral triangle is what you want your group to look like assuming it's not a one hole group that is.

[AtlLaw]

Is it really that simple?

AH HA!     Another meaningless and statistically insignificant test in the making!  Let's see...    I can load three batches of ammo, all the same except for ...          Nevermind, I agree with Bill... 

[Silvertp]

Somebody is pulling your leg.

Two touching and one wide is more often a bedding issue or a bad load with wide variance in velocity. An equalateral triangle is what you want your group to look like assuming it's not a one hole group that is.

I thought that might be the case.  If it were that easy to read a group and improve it, everyone would know about it.

Typically I pick my bullet and two or three good powders to use in working up loads.  Once I get something that shoots good, then I play with COL.  Ive actually improved groups from 1 1/2 inch to 3/4 inch just by moving the bullet closer to the lands.

Silvertp

[Graybeard]

Most tend to do that but honestly it's likely you could have done the same by moving further from the lands tho most find that hard to believe. Accuracy has more to do with barrel harmonics than it does how far the bullet is from the lands. Once you reach that magic spot that gives proper barrel harmonics you get good accuracy. I'm not one who believes there is but one spot where those harmonics come together for accuracy but if you find one I don't recommend wasing time looking for another.

[BruceP]

I agree with Bill on this one. To keep things simple. (at least in my mind) I always start close to the lands then seat bullets deeper as I go. That way I only have one direction to move and I dont have to wonder if the sweet spot is in the opposite direction of the way I'm moving. Also like bill I don't think that there is always onle one sweet spot as I have seen groups open at first when seating deeper then start to tighten as I kept going.

Bruce