QuickLoad variance

[Mike AVM]

I'm looking for general comments and consensus on the variance I experience using QL. I have two 300 Win Mags, one Kimber 8400 (26") and the other a Ruger with a 24" barrel. I use Hornady cases, albeit separate lots for each rifle, separated at purchase and never fired in the other rifle. With the Kimber and H1000, whether 180 or 200 grain loads, QL is pretty accurate regarding velocity. With the Ruger, my H1000 predicted velocity is 50-90 FPS faster than actual. I use the same chrony, a Labradar, on the same day with the same conditions. I have to significantly adjust Ba in QL to get the Ruger velocity to match. I primarily use QL to get barrel time and ensure that predicted pressure isn't too high. I've seen some predicted pressures quite high from reliable reloading manuals, primarily Nosler.

My question is have others seen a dramatic change from rifle to rifle for a given powder? I always have to shoot then adjust for RL-26. While great at giving higher velocity with less apparent pressure, from rifle to rifle it requires quite a bit of adjustment. Any thoughts appreciated.

 

[NWPilgrim]

One parameter that QL does not factor in is chamber size. A looser chamber I would think would give slightly lower velocity and lower pressure. Other factors not incorporated are actual barrel dimensions of lands and grooves, smoothness of barrel, etc. You input the nominal characteristics but that is assumed to be some average quality. Actual barrels will differ in exact measurements.

This is why QL constantly displays the warning to the effect that it is an approximate predictor of internal and external ballistics, and not to be used as an absolute predictor. It factors in things like barrel length but not the micro characteristics of the chamber and barrel. I only use QL to explore possibilities and get me in the small ball park of what I want to test. Then I cross-reference as similar loads as possible in multiple manuals (bullet and powder mfgrs). Then I do my work ups. My testing in my rifles is the ultimate truth. I think you are mis-applying QL to try to predict down to less than 50fps. Re-read the warnings in QL and see if you are taking that to heart or not.

 

[JimKirk]

It works that way in real life gun usage too ... So many variables that can and do add up to the total picture when comparing two identical gun ... much less comparing totally different guns ...

 

[Sofie007]

Actually I'm surprised that it's within 90 FPS!