Do you feel that OBT loading is worthwhile?

[fatelvis]

Just wondering if you guys load using QL and the OBT table and find that it does indeed provide a "shortcut" to an accurate load. Does it get you where you need to be accuracy-wise, or even close? Thanks

 

[LCazador]

I don't think it's a short cut. It can be added time in the end but then I don't think you should leave anything on the table when working for best accuracy and performance.

 

[Murray Brook]

I generally use the OBT when working up a new load. It gets me close most times, but rarely is it right on. It does save me some components in the long run, but your input into the program must be spot on.

 

[charlie b]

I found that using GRT (along with manuals) shows me where max pressure is at for the bullet and seating depth I am using. I then start 10-15% low and do a ladder to find the two nodes I am interested in. I've found the GRT calculated OBT is sometimes way off, so I basically stopped using it.

 

[kelbro]

I generally use the OBT when working up a new load. It gets me close most times, but rarely is it right on. It does save me some components in the long run, but your input into the program must be spot on.

Same here. The OBT calculated with GRT has been very close to a node on several occasions. Predicted high pressure within a couple of hundredths several times. I was quite surprised at how well it was able to model the loads.

 

[Martin52]

And same here, been using GRT for a few years now. Essential to input actual velocity data for the OBT calculation to predict the node/speed/pressure more accurately. Found it spot on for Berger 185 Juggernauts and 200.20x's. With 155's GRT seems to prefer ~ 2950-2970 fps, the target tells me 3020 fps for my rifle.

 

[kelbro]

And same here, been using GRT for a few years now. Essential to input actual velocity data for the OBT calculation to predict the node/speed/pressure more accurately. Found it spot on for Berger 185 Juggernauts and 200.20x's. With 155's GRT seems to prefer ~ 2950-2970 fps, the target tells me 3020 fps for my rifle.

That part was really interesting. GRT made an iniital prediction which was pretty close. After I shot the workup, I then input the measured velocities back into GRT and the new OBT that was calculated was within .1gr of my best group.

 

[Martin52]

Another thing, inputting actual velocities and running the OBT tab really helps if you are using small rifle primers. In my experience (.308), GRT predictions without actual data will generally reflect velocities from large primers as a 'base case' i.e. it will predict higher velocities compared to the same load with small primers.