Bullet seating depth effect, is it really?

[RDavies]

, but changing from jammed to jumped, always needs more powder to keep in the node.

Yes,
I had to add .5-.6gn to keep the same speed when switching to bergers "jammed versus jumped", should have read "jumped versus jammed"
Into the rifling= reduce charge for the same speed

[ovenpaa]

Moving from jammed to jumped *should* reduce initial chamber pressure so if you need to get back up you would add more powder so I agree with that, the thing is if you do then replicate the pressure and accordingly MV with say a jump of .010" do you see the same accuracy and if so is it not a better move to start with a jump and reduce potential pressure spikes?

This is one of the reasons I moved from VLD to Hybrids in my 7mm.

[RDavies]

Something I,m wondering about, is if you are running the low node, like I am, then maybe the jam gets to pressure up to where the powder likes to burn consistantly? Conversly, if you are pushing for a high node, then yes, the jumped Hybrids will be good for cutting peak pressures to a consistant, non peaky level. ??

[spud]

dont get hung up on fps nodes its the pressure nodes you want to concentrate on.

[ovenpaa]

My choice of hybrid was more based on the fact that they are not so sensitive to OAL so I was not going to end up putting 150 rounds up the barrel to find an optimum load as that is potentially 25% of the barrel life. With my F Open rifle I was trying to determine the optimum load in as few shots as possible which is never an easy thing to do.

Of course (moving off at a tangent now) this does mean I can never be sure in my own mind that I have the optimal load however if it can hold better than .5MOA at 600 yards then it should be good to go, I would apply this rule to most rifles other than bench resters who are looking for better than quarter MOA every time out. I think anyone that can hold the V at 1000 in their class is doing a lot more than just loading consistent and accurate loads.