Quick load velocity way off
can any of the guys that have quick load have a look at a load for me I have entered all my data and its saying my velocity should be 3133fps I fired the test load at the range and it cam out at 3422 measured by Labradar. my load details are
bullet 100 gr Speer BTSP #1408 cartridge .25-06 ack imp cartridge length is 3.180 barrel length 26" case capacity in h20 72.4 powder h4831sc charge weight is 58.0 gr I hear the program is pretty accurate but 269fps seems a bit extreme what data am I putting in wrong? |
My QL computes to 3160 MV.
Dave |
It's a calculation, not an actual measuring tool. I will trust my Magnetospeed over any calculation.
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here is the screenshot for it.
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Any Pressure signs as your velocity puts you over the safety limit, but who knows. No PS might be good to go.
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That load is is probably at max or over based on the load and velocity. An AI will usually get 100-200 fps over published non AI loads, you are almost 250 fps and 4 grains over published regular 25-06 load/speeds. That is very close to 257 Weatherby speed using a 26" barrel 100 grain bullet and H4831. I would be checking case head and rim expansion really close with that load.
Quick load is a great program but it is an approximation. The Chronograph is still far and away the best indicator of pressure. For an AI I start at 2 grains below published max for the non AI and work up till I get to 150-200 fps faster than max speed for the non-AI, adjusted for barrel length. You can push them faster but there is a real good reason Ackley blew up so many guns trying to get the last 50 FPS out of his cartridges. |
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I'd have a look at the labradar troubleshooting guide in this case. |
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As with any other Loading Manual predictions , start low and work up. |
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58.0gr avg 3422, QL 3418 58.5gr avg 3456, QL 3443 59.0gr avg 3469, QL 3468 this must be a variation in lot to lot burn rates? |
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It keeps H4831 with the default burn rate, etc |
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Can you accurately guess the pressures from velocity, or just come close? Can you accurately guesstimate the pressure difference between two different powders with the same MV ? For a man of your apparent reloading status, you should give it a try before dismissing it as an off-the-wall ballistic calculator. The guy that wrote the program is far more knowledgable regarding internal and external ballistics than all of us on this forum combined. Try it and find out for yourself. |
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I think the OP showed that example for three different charge weights. Fair 'nuff? |
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Your a real piece of work Elk ! |
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With default QL data, I get 3160fps
To get the results you measured, burning rate (Ba) has to be changed to 0.5034 and this is a 17% increase!!!! I have read somewhere, the Ba value cannot be changed more then 5%, as the simulation results would be meaningless. I don't know why the difference. Do you see pressure signs? If not, maybe another speed check with another chrony. |
there are no pressure signs, no case stretching/case head separation no cratering no sticky bolt no extreme recoil no blackening around the primer pocket. I also fired 7 shots at 52GR for fouling they averaged at 3195fps on the Labradar with a ES of 39 and a STD of 14.4
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QL Burn rates
Here you go Elk .. argue with Chris for a while. You might be able to get him straightened out.
http://www.the-long-family.com/Tunin...%20results.pdf |
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One big advantage to using Quick Load, if you adjust the burn rate and/or bullet weight to match your actual Velocity, put in an accurate H2O case capacity it spits out pretty accurate pressure numbers. This is not something you get just using just a Chronograph. Still need to verify it by checking over the case real good but I have never found a load that was adjusted to match the actual Chrono velocity, showed 50,000 to 60,000 calculated psi (depending on cartridge) or less to have high pressure signs of any kind.
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A chrono should give a true velocity of a fire arm especially a Labradar. Any load data we obtain may not match what our chrono tells us. There are to many variables in a fire arm to take load data as being what we will actually get. If the op is getting better then predicted velocities with no pressure take it as a bonus. Next time the velocities maybe way low and you may have pressure. Nothing man makes is 100% the same all the time.
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pregnant.. you either are, or you're not ! Which one ?:thinking-006: |
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Your average Chronograph readings have already taken in to consideration all the various discrepancies in that particular chamber, throat,barrel etc. and that particular load and that particular rifle, on that particular day (temp) I hope that's clear enough. Now, adjust the powder burn rate in QL to match those results. Document that particlar adjusted burn rate. Forever more,QL will produce excellent proximities to that velocity and pressure. If thats what you call fudging numbers, well, do it your way. I don't really care. |
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Of course I read it. What he meant by that is that if you arrived at a certain burn rate number with a clean barrel, then tried to duplicate it with a badly fouled barrel or some other difference the results could vary a bit. Maybe even a different barrel altogether for that matter.. That situation can be tweaked , or fudged if you will, by adding or subtracting a grain or three to the bullets weight to compensatefor the variance in MV and/or pressure. You can't do that with extremely large differences.For those of us who keep our rifles fairly clean it really doesn't present a problem. It works best when you want to get the QL predictions down to a foot or so of the original Chronograph average. |
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