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Quickload & OBT prediction with 230gn .30 bullets

chobham

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Full Member
Minuteman
Sep 13, 2012
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I've had some very good results using Quickload to work out optimal loads for my .308 rifles with 155, 175 and 185 bullets. I'm now trying to get 230s working in my 32" 10-twist barrel but things aren't going to plan...

I'm using Berger 230 Hybrids in Lapua brass with Reloder 17. The OAL is around 3.22" (barrel has been chambered specifically for the heavy Bergers).

A couple of days ago I tried loads from 41.6gn to 45.5gn of R-17 and every shot was chrono'd. When I plugged the results into Quickload and adjusted the Ba variable to match the measured MV of one of the loads, I find that when I then change the charge weight to match one of the tested loads, the predicted MV is way out. I've tried tweaking bullet weight and weighting factor but I can't find any way to make the velocities tie up with my test data across the range of loads I tested.

This means I can't currently use it to work out loads based on the OBT method.

Does anyone know why this is going wrong and whether there's something else I should be doing to get this to work with this bullet/powder combination?

I've double checked the bullet measurements and case capacity to make sure they're spot on.

Here's an example of what I'm getting:

Load Actual MV QL MV with Ba changed to match 41.6 load
41.6 2257 2257
43 2355 2328
44 2430 2379
45 2500 2429

If I correct the Ba to match the 45gn load I get this:

Load Actual MV QL MV with Ba changed to match 45 load
41.6 2257 2337
43 2355 2405
44 2430 2453
45 2500 2500

I don't know what to try next, other than to go back to ladder tests and group tests to try and find the nodes.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

Are you jumping or jamming your bullets? If jamming, you need to up your start pressure.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Temp9</div><div class="ubbcode-body">Are you jumping or jamming your bullets? If jamming, you need to up your start pressure. </div></div>

With these test loads, the bullet is 'soft seated' in the rifling, but I tried upping the start pressure to see if that helps to bring things back into line, but it makes it worse if anything.

The predicted velocities in QL are diverging away from the actual velocities measured (from the point where I have matched the QL velocity with measured velocity by adjusting Ba) in a straight line, so actual and predicted velocities are linear as the powder charge changes, but increase/decrease at different rates.

The fact the measured velocities are linear, leads me to believe that my measured data is accurate enough. I just can't see why the QL data diverges and what might cause this.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

Would you mind posting necessary information here, like seating depth and fired case capacity? I'd like to play with it to see if I can get it to perform properly.

Also, get in contact with the guys at Neconos (the QL guys). Maybe they know something we don't.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

No problem.
Here is my starting load, before tweaking the burn rate. Actual MV was 2257. Quite a bit away from QL's 2374 fps.

ql1.jpg
 
Re: Quickload & OBT prediction with 230gn .30 bullets

I did a bit more searching last night and found a mention that Quickload had a data update around June this year, which might include a better model for the Reloder powders.

I checked in May when I first looked at the heavy Bergers because they weren't in there and at the time I know I had the latest data, but now I'm wondering if I get this data update it might improve the results I'm getting with R-17.

I'll check today.

Did anyone here get the data update and how would I know if I already had it? Are the 215/230 Hybrid Bergers in it?

ETA - seems from what I've heard elsewhere that the RL-17 model was not accurate in the previous data and that the latest data upgrade may improve this and does add the new heavy Bergers. Hoping to get the update in a week or so and I'll report back my findings.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

I think I have the more recent version. It has the heavy Berger Hybrids. My results mirror yours almost exactly (within a few fps). I got my numbers a little bit closer by using the "Setup long barrel friction" with a setting of "4350 psi". Modifying the Ba to "5152" with that setting gives a low velocity of 2257fps and a high velocity of 2449fps.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

i have a pressure trace machine that measures my internal ballisitics

Quickload has never matched my pressure trace in these 4 area's.

velocity
time to max pressure
max pressure
exit time

<span style="text-decoration: underline">at best QL</span> and the PT machine, will match 3 of those area's , but not the forth. Usually quickload will only match 2 of these areas, generally velocity and time to pmax. Which is... useless for the most part.

sometimes quickload is only off by a marginal percent , other times, an unacceptable percent. I dont trust quickload for shit other then getting me started, or giving me ideas. Its to theoretical. Better off determining nodes from paper tests, then looking at QL outputs.
 
Re: Quickload & OBT prediction with 230gn .30 bullets

My faith in Quickload has been restored!

Did a lot more range testing today across a wider load/velocity spread and carried out group testing while chrono'ing every round.

The results are summarised in this graph:

230gn-bt-comparisons-corrected_zps087b0b02.jpg


The yellow line graphs the velocities against powder charge using the default powder data in Quickload.
The green line uses the same powder charge numbers but the Ba variable has been tweaked down to match one of the actual velocities I measured.
The red line is the same powder charge numbers but all the velocities are actual ones measured today.
As you can see, with the Ba tweaked, the actual and predicted velocities are a very close match, particularly once I get above approx. 44.2 grains.

I've concluded from this that the main reason the previous results didn't add up was because I simply didn't have enough data across a wide enough load spread. My previous tests were with loads between 41.6 and 44 grains of R-17. As you can see from the graph, my data at the lower charge rates was obviously inaccurate, so it looked to me as though the real vs. predicted velocities would diverge as the charge weight increases, but once I added more data, it matches well.

At this point, it's probably a good idea for me to remind everyone that this load is based on my component/rifle combination and should not be used by anyone else without working up to it and checking for signs of over-pressure as you do.

I hope my experience with this has been useful to other QL users. Feel free to look for any mistakes I might have made in my interpretation - I'm still learning!
 
Re: Quickload & OBT prediction with 230gn .30 bullets

Interesting. What would the change in the slope of that line represent? Is that the point where you achieve 100% powder burn? Obviously, it's an area that QL is predicting, so it has to have some significance, right?
 
Re: Quickload & OBT prediction with 230gn .30 bullets

Ah, hold on. I've just spotted that the X-axis on my graph isn't linear, so that would account for the ramp-up. I'll change it and re-post. Changed the graph and text in the above post. All seems as it should be now!