quick load?

[Gregg C]

Here is a screen shot of a 300 WM load I made using the overbore related weighting factor. The Barrel time is 1.256. From the tables node 5.5 would be 1.266 ms. This is a 0.8% difference. This is a 5 shot target at 100 yds with this load. Changing the powder weight a bit in either direction does not give this result. I would love to see someone else provide some kind of result comparing OBT barrel time with a target result. I have things like this for all my rifles. Anyone who wishes can take this data and run it through Gordons. Gordons uses a single Seibert factor for all examples of a given cartridge. I change the weighting fiactor for any cartridge example with a different water case capacity.View attachment 650187View attachment 650188

 

[Gregg C]

@VarmintBob , I'd like understand how you did that. True velocity after finding load that shot good, then use OBT from that ? If you don't mind, walk me through the process , please.

 

[VarmintBob]

It took me about 7 years to develop a procedure. It starts with QL finding a barrel time starting point. Then shoot a few groups. Load development takes me about 15 shots now. I'm not willing to spill all that into a public firum.

 

[cdherman]

QL is not magic. As for barrel timing etc etc. I think that is why we shoot groups. But QL allows you to make a bunch of basic calculations. It can give you density measurements so you have an idea of case fill rates. You can play with various known bullet profiles and seating depths. It does NOT however help you with bullet jump. It can give you guestimates of muzzle velocity, based on your barrel and compare various powders. It can give you ideas for cartridges that you have little data for.

IT IS ABSOLUTELY NOT A TOOL FOR A NEW RELOADER TO USE. A new person to reloading should go by published books (and read the darn thing too) first.

 

[VarmintBob]

I find bullet jump to be a minor contribution to making a load work well. I should have a new load done today. I shot 4 bullets yesterday to calibrate the powder. I'll shoot 3 groups today and we'll see what comes out of it. 62gr ELD-VT in a .223. New bullet for me in .223. QL is not magic. It is an internal ballistics model. If you know how to use it, you can very accurately predict what a set of components will do before you shoot. That is the purpose of a model.

 

[Songdoger]

I love QL! I have input all my old accurate loads prior to QL and adjusted BA factors, case capacities and temps to match velocities. The barrel times were incredibly close. It's also nice to see how a good winter load needs to be adjusted for summer loads. Some powders have terrible temp sensitivity even when 5k below max pressures let alone being on the edge of max.

 

[VarmintBob]

The reason I don't buy temp insensitive powders anymore. I have also found that due to the huge differences in chamber sizes from one rifle to another that the only powder weight data in a data book that has any utility is the starting load.

 

[VarmintBob]

The reason I don't buy temp insensitive powders anymore

I shot the following after working out where node 3 would be with AR-Comp and 62gr ELD-VTs in a .223 bolt action. I was expecting to see a barrel time node around 3195 fps. I shot the 4 at the large diamond to get velocity numbers over a range of powder loads. 22.5 gr to 24 gr. That let me calibrate the powder/bullet combination. I guessed (using QL) that 24.5gr was going to be about node 3. So I shot 3 groups of 3. 24.4gr, 24.5gr and 24.6gr. The 24.5gr group is the upper right. All 3 groups had a flyer but the smallest spread was 24.5gr which what I was expecting. I'll shoot a few more of these but I suspect that upper right group is barrel time Node 3. So a 13 shot load development. I plan to go do the same thing with Stabal-Match and see if I can get a bit better group out of it