POI from full to neck size

[SSE]

I have a 308 that shoots very well with both neck and f/l loads. It shoots a little better with just neck. My neck sized loads shoot about 2" higher and 1" to the right than f/l at 200 yards. That is more than I get with any other rifle. Just wondering if anybody else has this much POI between neck and f/l

 

[rkittine]

Have you chronografted the two different loads to see if you are getting different velocities due to differences in net case capacity?

Bob

 

[SSE]

Good idea. I did not think to chrono, it being same load. I will do that.

 

[mikecr]

Difference large or small is still a difference.
You should choose your sizing plan and do a load workup with it.

 

[SSE]

It is the size of the change that made me take note. 2" high and 1" right.

 

[RegionRat]

That is a dramatic difference, I agree.

You may need to investigate the sizing process more deeply. Is the same die being used? In other words, are you using the FL die and just backing it off, or using a different die to neck size? The important difference being the resultant neck diameter between two different dies can be dramatic.

Curious about the specific load, powder, charge weight, bullet, seating depth, etc. and what is the chamber or bbl? Is this a compression load for instance, or one with lots of space? Seated into lands, or jump?

ETA: this is another example of when a Chrono speed average and stats would be good to know.

 

[JFrank]

How much brass movement when FL sizing

 

[SSE]

Short range load, 308 125 gr. 47.0 Tac, not compressed, jumped. 2 dies,less neck tension with neck size than full length die.
Tight chamber in Krieger barrel. Fired brass needs almost no sizing. Have not had a chance to chrono the loads side by side yet. That will be my next step.

 

[JFrank]

I was at first thinking case volume has a hand your poi shift.

I've noticed the lighter neck tension has affected poi on my targets however the shot placement was not consistent.