QL issue...?

[nightwalker]

I have used an old version of Quick Load for years (the one on a floppy Disc - do new computers even have an opening for these now?), and my actual muzzle velocity readings have always been close (within 20-30 fps) to the predictions QL has said.

Recently I upgraded to V3.6 of QL, so that I can enter my 6.5x55AI cartridge into it to get load predictions etc.

My load is 6.5x55AI, 50gr N160, 142gr SMK

Now after reading up about the various "tweaks" to QL eg - actual bullet length (1.359 for 142gr SMK), case capacity H20 in grs (62.60grs), barrel length (22.5"), cartridge length (3.125") and actual temperature (60 F) - QL is 166 fps slower than what my chronograph says (chrony says 2837fps, QL says 2671fps)??

So why is this???

Anybody care to check on my results with any other load predictor or offer an explanation, not bothered if chrony is for the bin (CED), but with its muzzle velocity readings my drop charts have always been about bang on, out to 1200 yards?

Very puzzling??

Regards NW

 

[wooger]

Do you have actual dope that supports your chrono? I'm using a recent version of QL and have found that the velocity prediction in right on for some of my cartridges and the far off for others just like you are experiencing.

N/M I just saw the bottom of your post, sorry.

 

[nightwalker]

Maybe I am not alone in not fully understanding what all the buttons and tweaks do on QL to get an accurate prediction?

On another forum altering the "weight factor" to a lower number was suggested, anyone care to expand on this please?

Regards N/W

 

[mikecr]

No, don't mess with weighting factor until you find the problem.
You didn't mention the POWDER, and starting pressure.

 

[nightwalker]

Yes the powder is viht N160, 50grs (first post)

How do I work out starting pressure?

 

[Jay Christopherson]

Maybe your powder lot is a bit faster than what QL has. Try tweaking the burn rate (Ba) a bit to get your numbers to match up.

 

[TheSnake]

Maybe your powder lot is a bit faster than what QL has. Try tweaking the burn rate (Ba) a bit to get your numbers to match up.

When messing with burn rate, how do you know when you have gone too far? What is the vareance of powder burn rate, give or take what percentage for any given powder?

If someone offered an online training class for advanced QL usage, I would pay to go to that and I bet others on this site would too.

 

[Jay Christopherson]

I know I have gone too far when one load matches up, but the others don't. For example, if I can match the velocity for X number of grains by modifying the burn rate, but increasing (or decreasing) by a half grain or something doesn't match up with the actual data, I know that my issue is not burn rate- or at least, there is some other factor at play as well.

Usually by the time I start messing with burn rate, I've already verified (and re-verified) all other static factors like case capacity, cartridge OAL, bullet length/weight, etc... by the time I get to burn rate, I rarely have to modify it very much and when I do, it matches up pretty precisely at various powder loads (all other variables being unchanged). I most often have to modify it when changing powder lots and usually by a few percentage points at most.

There's no hard and fast rule for variance (that I know of), just like there is no hard and fast rule for bullet variance between lots of the same type.

Maybe your powder lot is a bit faster than what QL has. Try tweaking the burn rate (Ba) a bit to get your numbers to match up.

When messing with burn rate, how do you know when you have gone too far? What is the vareance of powder burn rate, give or take what percentage for any given powder?

If someone offered an online training class for advanced QL usage, I would pay to go to that and I bet others on this site would too.