From Winchester to Lapua

[jpbaker]

Im picking up some new brass for a couple of my rifles, and I am a little concerned about having to do new load development.

My .308 right now is shooting Nosler Brass, and my .223 is using Winchester and a few Remington.

When switching over to Lapua brass, will I see a big difference in case capacity/pressures. I'm not looking forward to working up new loads.

TKS
JPB

 

[maynard]

Use the load you have now as a baseline, and use a Chrony. Match the velocity using the new brass. Testing done.

 

[c-fbmi]

Lapua is 10 gns heavier than W-W in 308, that I know for sure. However unless you are running redline that shouldn't make a whit of difference.

 

[Holleyman]

Another difference you'll notice is that Lapua has a square primer pocket that requires very little cutting to uniform, Winchester is a mess that requires a lot of work. The flash holes on Lapua are very true and I have yet to cut any major burrs off of the inside flash holes. Again, Winchester isn't even close to consistant, often with much swarf being removed.

 

[bigedp51]

Weigh your empty cases and then check the weight after filling them with H20 and this will give you the correct answer to your question. Bullet seating depth and case capacity have a big effect on chamber pressure.

The only difference below between these two Quickload charts is the case capacity of the cases, the bullet and powder charge are the same. The higher pressure chart is for a case with a capacity of 28.0 grains H2O and the lower pressure chart is a capacity of 30.6 grains of H2O.