QuickLoad vs Bullet Manufacturers Loading Data Delima

[Gordy]

I just purchased QuickLoad. Using Varget with a 155.5 .308 caliber Berger bullet, I can load up to 47.1 grains without going over the line into "Dangerous Load-Do Not Use" using QuickLoad. The Berger reloading data sent to me by Sinclair, who acts as their technical staff, shows the max load as 44.6 grains. That's a difference of 2.5 grains. I used the QuickLoad data, starting 10% below 47.1 grains to see if any pressure was put on the case as well as the primer. When I got up to the 47.1 cartridges, I had no pressure problems (the calculated pressure is 59,312 psi at 47.1 grains).

My question is this-why is Berger data so low? Am I OK to use QuickLoad to figure all my charge weights in the future? Help!

Gordy

 

[msnations]

Berger is probably being conservative - 55K psi perhaps? Nailing down the safe upper limit is practically impossible given the variability in barrels, powder, primers, etc.

 

[mikecr]

You can use QL, and calibrate it with chrono numbers. But no matter what, you have to validate your max load with a creeping up to it. NOTHING can predict this for certain.

 

[Forum Boss]

With QuickLOAD you need to measure your actual case capacity. It makes a big difference -- as does seating depth. With a printed load manual, they can't factor in case capacity and seating depth. Additionally with the .308 there are "normal barrels", "tight bore" barrels, and then the 5C and 5R variety that typically take more powder to reach the same velocity. Add to that you have significant lot to lot variances for Varget powder, plus small and large primer types. What does it mean? In the real world I have one friend shooting a "max load" of 47.0 grains Varget with 155.5gr bergers (small primers); another friend, shooting the same bullet, but loading shorter, in a tighter barrel, with lower-capacity brass and large primers, maxed out at 45.0 grains Varget. Two full grains difference!

Even with QuickLOAD you need to start low. It can be very useful, however, in showing how pressures can change with seating depth and different brass brands, with different internal capacity.

 

[RonAKA]

You may want to ask Berger. I've seen it posted that Berger also uses Quickload. If so they must be using different input parameters. In the end the pressure signs in your gun and cartridge are the judge of what works.