Velocity drop with neck sized from virgin Lapua

[rodkayak]

I neck sized 100 Lapua 6.5 x55 virgin cases. Once they were fired, I neck sized them again but there seems to a mv drop as they are now shooting we'll below the neck sized virgin brass impact point at all ranges. Is this normal please?

 

[Milk no sugar please]

Normal. The cases started out life at CIP spec and you have fireformed it to your chamber increasing its internal capacity. The same powder charge has more space now so there is less pressure and as a result, velocity. Full length size your cases.

 

[Scuffy]

Or tweak load in neck sized brass

 

[rodkayak]

Normal. The cases started out life at CIP spec and you have fireformed it to your chamber increasing its internal capacity. The same powder charge has more space now so there is less pressure and as a result, velocity. Full length size your cases.

Makes sense

 

[rodkayak]

Or tweak load in neck sized brass

It's dropped 4 cm at 100m. I will load with an extra grain of powder. Thank you.

 

[Utectok]

It's dropped 4 cm at 100m. I will load with an extra grain of powder. Thank you.

If it’s dropped that much at 100m it’s not a drop in Muzzle Velocity because a drop of that much at 100m will be a huge drop in MV. 50-100fps is barely detectable at 100m with normal dispersion. And I do not believe you could have dropped anything more than that. Borrow a chronograph and test the load or shoot it to 300m plus then calculate the speed via drop.

 

[Utectok]

Also don’t neck size no one does these days

 

[palo]

It's dropped 4 cm at 100m. I will load with an extra grain of powder. Thank you.

I would zero it again at 100m then check your drops at distance before adjusting the load.

 

[Utectok]

It's dropped 4 cm at 100m. I will load with an extra grain of powder. Thank you.

I’m not sure a “stick another grain in” is the correct approach to reloading. Advisable to take a more precautionary approach.

 

[rodkayak]

I’m not sure a “stick another grain in” is the correct approach to reloading. Advisable to take a more precautionary approach.

I have backed off from higher loads already and have already safely used 1 extra grain of powder

 

[Jagged77]

Do you have some of the virgin cases to shoot alongside the once fired neck sized cases? If you’ve shot them all and no longer have a reference point then maybe your zero has shifted or something else is awry with your set up.

 

[finnbear270]

I’m not sure a “stick another grain in” is the correct approach to reloading. Advisable to take a more precautionary approach.

Rod kayak, This^, You been chatting with Kenbro?