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Just read an interesting article about the above thread title.

If (big if!) I understand it correctly you create the usual incremental series of increasing powder loads (within sensible limits) and fire at a vertically elongated target board (ex pecting the POI to rise as loads increase) & looking for a 'sweet-spot' where several loads group together..... this being the 'node' to do any fine tuning from.

My problem is that with at least two of my rifles (308 Win & 260 Rem) I see LOWER POI with increased powder loads despite an identical POA ..... much head-scratching and a little bit of internet research points the finger at barrel harmonics and the faster round leaving the barrel sooner and at a lower point in the recoil cycle...so it prints lower....anyone else see this in their rifles?

I see mine move right on the 7mm. I look for load increments that group closer than others.

ovenpaa wrote:I see mine move right on the 7mm. I look for load increments that group closer than others.

Thats pretty much what I do ... just makes for interesting reading to see if there are advantages to another method.

I know that I am tired, but are your findings not what you would expect? a more powerful load will require less elevation and as such must surely be flying straighter.

DM

What distance to you test over? Dependant on you sights i would say start at a minimum of 200m and ideally get out to 600 fairly quickly as it is easier to determine differences.

Dangermouse wrote:I know that I am tired, but are your findings not what you would expect? a more powerful load will require less elevation and as such must surely be flying straighter.

DM

Everything at 100 yards for initial testing and same POA.... I would have expected the more powerful load to shoot higher as it is shooting flatter .... instead during recent load testing my 308 shot lower with a higher charge.

Just seen Ovenpaas' post..... After adjustment for POI I move up the range distance and develop drop tables in the usual fashion..... IE Chrono & get a ballistics program (Quicktarget and Bulletflight) for theoretical scope come-ups and then field prove to confirm. That all works well ... I was just 'thrown' initially by the POI results... I'm used to it now!

If your bullet is travelling faster and is still climbing at 100 yards the impact poit will be lower

20series wrote:If your bullet is travelling faster and is still climbing at 100 yards the impact poit will be lower

are you saying a faster bullet shot out of a rifle with the same pitch will climb slower than one with a lighter load?

how is this possible?

seems wrong :/

As I said... I think that its due to a faster load exiting the barrel earlier in the recoil cycle (IE earlier in the barrel 'jump' so at a lower stage when bullet exits so it prints lower on target) PLUS (possibly) something to do with barrel harmonics .. IE it is at a different up/down vibration point as generated by that load. Thats as far as my theoretical knowledge extends!