QuickLOAD Advice

[Roninco]

How much do you adjust burn rate factor (Ba) to true the actual muzzle velocity (MV) to QuickLOAD predicted velocity? Is there a guideline as to how much one should limit the amount of correction? One recommendation I read was no more than 5%. My predicted MV is 165 fps slower than actual. In order to reach my actual MV I must increase Ba by 10%. Is this too much of an adjustment or do I have an issue somewhere else?

I have accounted for the common variables such as COAL, barrel length, water capacity, and actual temperature:
6mm Creedmoor
108g Hornady ELD-M
COAL: 2.788
24" barrel
52.9g water (Hornady brass)
39.6g H4350
44 degrees F

Default Ba=0.5009 and weighting factor 0.5
Predicted MV=2778 fps
Actual MV=2943 fps

If I adjust Ba to 0.565 and the weighting factor to 0.4 the predicted MV becomes 2943 fps.
Advice and recommendations welcome. Thanks.

 

[ShtrRdy]

I recently was having the same sort of trouble. I was having to adjust Ba by 10%, or a little more, to get QL to match what I measured with a Magnetospeed. At this time I'm thinking my main problem is the powder drying out which causes two problems. 1. The powder granules are a little lighter so when you measure out a charge weight you get more granules. And 2. Dryer powder has more energy than damp powder. This last point is something I learned recently. I live in a dryer climate and don't have any sort of climate control on my reloading room.

Do you enter a bullet length?

 

[Roninco]

Yes, bullet length 1.264" +/- .002"
I too live in a dry climate but loading area is about a constant 70 degrees with low humidity.

 

[Hawk in WY]

My immediate thought is you are into the lands, but your COAL of 2.788 suggests you calculated that distance.

The other option is the weighing factor where QuickLOAD recommends 0.33 for overbore bottleneck cases. I suppose 6 CM qualifies.

That brings the calculated velocity up to 2787 so not much difference.

I shoot mostly all copper hunting bullets which require a change in shot start pressure of 6525 but this would seem to not apply with the 108's.

Powder burn rates will vary as much as 10% from lot to lot, but a 10% change in burn rate from what QuickLOAD obtained probably from the powder manufacturer says they must have had a particularly slow lot.

The velocity of 2943 would seem to be well below pressure but remember QuickLOAD is only an estimate.

I would adjust the burn rate and come up to 41.0 gr which should put you on a node.

Let us know how that shoots.

 

[can1010]

have you tried a load workup with a different bullet in the same weight class to verify your BA and weighting factor changes? does the pressure signs match what QL predicts for pressure? reason for asking is because i have been raising the shot start pressures on hornady bullets because of the long bearing surface. i seen this when going from berger hybrids to elds and the BA was way off but by using shot start pressure i was able to then keep the same BA and weighting factor

 

[Hawk in WY]

Predicted velocities are reasonably close to actual with cup and core bullets and the default starting pressure.

I'm seeing significant differences using the default starting pressures with all copper bullets. Increasing the starting pressure to 6525 put me reasonably close to actual so that is what I now use.

I guess that means the answer to your question is yes.

I can't really comment on pressure signs because my experience is pressure signs don't appear until well over safe pressures. I have not found signs of pressure if QuickLOAD predicts less than max pressure if the predicted velocity is close to the actual. Velocity is a much better sign of pressure than the usual suspects.

Hope that helps.

 

[Mikecr]

I doubt a big powder adjustment is needed.
Have you tried other QL 24cal barrels (differing cross sectional bore area)?

 

[nksmfamjp]

I doubt a big powder adjustment is needed.
Have you tried other QL 24cal barrels (differing cross sectional bore area)?

I'm not sure who this is directed at….I have't adjusted Ba yet as it seems to be a property of the powder which I cannot single out. I do adjust what I can measure. I adjust that case ratio occasionally.

im trying to figure out start pressure for monos vs cup n core.

 

[Roninco]

I doubt a big powder adjustment is needed.
Have you tried other QL 24cal barrels (differing cross sectional bore area)?

No. Would I keep the default Ba and adjust cross-sectional bore area until MV matches?

 

[ShtrRdy]

I doubt a big powder adjustment is needed.
Have you tried other QL 24cal barrels (differing cross sectional bore area)?

How do you select other QL barrels?

 

[Redfoot Ranch]

How much do you adjust burn rate factor (Ba) to true the actual muzzle velocity (MV) to QuickLOAD predicted velocity? Is there a guideline as to how much one should limit the amount of correction? One recommendation I read was no more than 5%. My predicted MV is 165 fps slower than actual. In order to reach my actual MV I must increase Ba by 10%. Is this too much of an adjustment or do I have an issue somewhere else?

I have accounted for the common variables such as COAL, barrel length, water capacity, and actual temperature:
6mm Creedmoor
108g Hornady ELD-M
COAL: 2.788
24" barrel
52.9g water (Hornady brass)
39.6g H4350
44 degrees F

Default Ba=0.5009 and weighting factor 0.5
Predicted MV=2778 fps
Actual MV=2943 fps

If I adjust Ba to 0.565 and the weighting factor to 0.4 the predicted MV becomes 2943 fps.
Advice and recommendations welcome. Thanks.

In the version I am running the default Ba is 0.5130 and I run v3.9 and my latest update is 12.31.20.

I generally don't adjust & true up the QL default numbers for a cartridge until I am able to measure the water weight in fire-formed cases but some of the default 6 CM numbers can be 'trued' prior to loading a round. For the default 6 CM water weighting I adjusted to .45 prior to looking for powder choices for a specific projectile. The water weighting formula I use is - (Cross-sectional Bore Area/Case Capacity)*500.

And yes, I have adjusted Ba by 10%+, once all other known input factors have been trued with real world data, on specific lots of powder before to align with LR and MS MV results.

 

[Carey Farmer]

Ten percent adjustment of Ba seems like an awful lot. That's the difference between Retumbo and H1000. Don't think I've ever seen that much variation between lots of powder.

QL says to add 7200 psi to shot start (initiation) pressure if the bullet is seated to touch the lands. My experience is that's a good number for bullets seated anywhere close to the lands.

 

[Roninco]

Ten percent adjustment of Ba seems like an awful lot. That's the difference between Retumbo and H1000. Don't think I've ever seen that much variation between lots of powder.

QL says to add 7200 psi to shot start (initiation) pressure if the bullet is seated to touch the lands. My experience is that's a good number for bullets seated anywhere close to the lands.

I'm 0.030" off the lands so not sure that applies?

 

[Willys]

QL can be way off at times. Retumbo gives really crazy numbers with QL at times.
Just adjust until QL matches your velocity ( how are you measuring that???)