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QL v3.6 just arrived and its conflicting info

 
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  #1  
Old 05-29-2010, 07:07 PM
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QL v3.6 just arrived and its conflicting info

Ok my quickload v3.6 just arrived and I already played with it enough to make my brain hurt. Actually the program seems simple enough however one thing has me a little confused. I have always been under the impression that seating a bullet closer to the lands or increasing the cartridge length will increase preasure.

So I start dropping in my load info to see what the program gives me. I already have some retumbo loaded up behind the 150 Bergers so I wanted to check what QL would give me for preasure and velocity. I know what the seating depth is and the OAL so I entered that info as well (2.895).

After I got all the data I thought I would see what happens to the preasure by reducing the OAL, seating the bullets further into the case and creating a little more jump (2.695)

To my surprise preasure increased and so did the velocity? HUH? The only thing I changed was to reduce the OAL from 2.895 to 2.695. Presure and velocity went from 56524psi 3079fps to 62591psi 3162fps. What am I missing here?

I will post screen shots as soon as I figure out how.


Last edited by datsjeep; 05-29-2010 at 07:17 PM. Reason: pic added
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Old 05-29-2010, 07:41 PM
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Re: QL v3.6 just arrived and its conflicting info

By seating the bullet farther into the case by .2" you readuced the case capacity and therefore increased the pressure
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Old 05-29-2010, 08:05 PM
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Re: QL v3.6 just arrived and its conflicting info

OK, it also does it if you are only using 95-99% of case. Is that normal? I am still really confused by this. I have not found a single scenerio where seating the bullet closer to the lands will increase preasures in the QL program
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Old 05-29-2010, 08:05 PM
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Re: QL v3.6 just arrived and its conflicting info

Quote:
Originally Posted by jwp475 View Post
By seating the bullet farther into the case by .2" you readuced the case capacity and therefore increased the pressure
Exactly.

To further expound.....

You will need to modify the start pressure setting to account for pressure differences unique to your rifle/throat/bullet combination when changing seating depths. That is not an automatic feature...the user will need to input this.

A method I've used successfully, is to load a string of rounds at varying charges, at all the same seating depth.

Record the velocities for the string.

Then use the case weighing factor/start pressure to "calibrate" QL for your rifle, until you can plug in the lowest charge and see a velocity that matches what you saw for that charge, and then do the same with the high charge.

When I'm able to input the "low charge" of my string, and the "high charge" of the string, and see that both velocities are close to what the chrono saw....then I feel good about the start pressure/case weighing factor for that powder/bullet/seating depth combination.

You then should be able to correlate the case weighing factor/start pressure figure to other powders, but not seating depths....if you change the seating depth, you'll need to make a change to start pressure once again.

This all assuming of course, you can trust your chrono results, and didn't forget to account on the effects of temperature can have with your powder

Reminder/disclaimer....QL is not a substitute for a pressure barrel in a laboratory with a strain guage. One must exercise caution, especially when operating at the upper performance levels IAW published loading data when available.

Good luck!
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Old 05-29-2010, 08:32 PM
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Re: QL v3.6 just arrived and its conflicting info

That makes sense, you adjust both the wighting factor and the shot start pressure. How do you determine which one to move and how much to move them?
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Old 05-29-2010, 11:40 PM
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Re: QL v3.6 just arrived and its conflicting info

QL sees the Case weighing factor is an "efficiency" factor, specifically a relationship between case capacity and bore diameter.

.40 is a good place to start for the 338 Edge, and a 300 RUM Improved seemed to work with .36 with most loads/powders.

I would look at your case and compare it's relationship to one of those as a benchmark, and then adjust to start.

Lower case weighing factor number, equals less total pressure, but more velocity with a given powder charge/bullet weight.

Higher case weighing factor number, equals more total pressure, but less velocity....

Start pressure numbers are just like you'd think....

Higher start pressure, more total pressure and more velocity for a given scenario.

Lower start pressure, less pressure and less velocity for a given scenario.
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Old 05-30-2010, 12:08 AM
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Re: QL v3.6 just arrived and its conflicting info

I am very interested in acquiring Quick load and was reading your thread when I realized that you have 72.5 gr of Retumbo under a 150 Berger! Not trying to be nosy but that will lock up the bolt on my 270 WSM with 140 Bergers, just wanted to give you a heads up just in case. If you can safely light it in your rifle it should be good for over 3200fps thought.
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