Massive difference between Official load data and quick load
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Shotgun572013
Well-Known Member
A quick word guys. I noticed a post on a forum the other day from about ten years ago where an ( experienced ) reloader was recommending a newbie a load which was a good two grains over the max in my Nosler reloading book. I don't know if he's still with us !!!
The key to Quickload is tuning your powder burn rate to both chrono data and validated trajectories from drop testing.
Just today I had a really good example of this. 6mm Creedmoor.
1. I measured a random selection of 10 bullet lengths and averaged.
2. I measured the water capacity of 10 fired cases with their spent primers obviously still in place, and averaged. With overbore cartridges make very sure that you’ve got all the air bubbles out.
3. I calculated the weighting factor using the equation from wherever I got it from...
4. When the 10 cases were dry I checked their lengths, and averaged and also doublechecked that my COAL was entered correctly and not the SAAMI default.
5. I selected my powder type (H4350) which had already been tuned to .243 Winchester and 6.5 Creedmoor, and saved in QL as a custom powder. It is a fact of life that powder burn rates vary from lot to lot.
6. The model velocity was 2,940fps.
I loaded five bullets using five of the 10 dry cases, now neck sized only and with a fresh primer. The average muzzle velocity over the chrono was.... drum roll... 2,936fps.
I am pretty confident that if fellow Quickload users follow exactly the same process they will see similarly close representations of reality. My .308 with Varget was the same, give or take. The secret being that by the time I got to model my current bullet I had already tuned the powder several times, each time the amount of change to the burn rate lessens to the point where you really are making very small changes, or none at all.
I try to do all my load development and powder testing at the hottest time of the year rather than the coldest, for the reasons that we understand. When winter shooting I am very careful to set my ballistics app according to the meteorological and altitude conditions in which I’m shooting. This compensates for the drop in oompff from the colder temperatures. I honestly couldn’t tell you how much of a change it makes because I don’t really pay any attention to it, the only output I am interested in is clicks.
I should emphasise again the importance of not just using your chrono data. I have found that sometimes it’s very close and other times it’s a bit off. By off I mean I will go and do a low altitude drop test and the ballistics app recalculates the muzzle velocity required to achieve the measured trajectory. Sometimes the recalculated muzzle velocity is a fair few feet per second off the chrono average, like 30 or 40fps. But the validated trajectory from drop data always works. (If I cannot do a low altitude test then I make damn sure that I set the barometric pressure, altitude and temperature correctly. Don’t you just love smart phones.)
The other thing the drop test does is compensate for any differences in BC. I find overall that the ELD bullets actually fly better than what it says on the box.
These small differences in velocity add up, but by the time you end up with a number you are happy with and hits the little gong, you can tune your powder burn rate. This works really really well as long as you stay within the same powder lot. I think this is easier for us to do than it is for you guys because there is no limit to how much powder we can carry here. You fellas probably have a limit?
Just today I had a really good example of this. 6mm Creedmoor.
1. I measured a random selection of 10 bullet lengths and averaged.
2. I measured the water capacity of 10 fired cases with their spent primers obviously still in place, and averaged. With overbore cartridges make very sure that you’ve got all the air bubbles out.
3. I calculated the weighting factor using the equation from wherever I got it from...
4. When the 10 cases were dry I checked their lengths, and averaged and also doublechecked that my COAL was entered correctly and not the SAAMI default.
5. I selected my powder type (H4350) which had already been tuned to .243 Winchester and 6.5 Creedmoor, and saved in QL as a custom powder. It is a fact of life that powder burn rates vary from lot to lot.
6. The model velocity was 2,940fps.
I loaded five bullets using five of the 10 dry cases, now neck sized only and with a fresh primer. The average muzzle velocity over the chrono was.... drum roll... 2,936fps.
I am pretty confident that if fellow Quickload users follow exactly the same process they will see similarly close representations of reality. My .308 with Varget was the same, give or take. The secret being that by the time I got to model my current bullet I had already tuned the powder several times, each time the amount of change to the burn rate lessens to the point where you really are making very small changes, or none at all.
I try to do all my load development and powder testing at the hottest time of the year rather than the coldest, for the reasons that we understand. When winter shooting I am very careful to set my ballistics app according to the meteorological and altitude conditions in which I’m shooting. This compensates for the drop in oompff from the colder temperatures. I honestly couldn’t tell you how much of a change it makes because I don’t really pay any attention to it, the only output I am interested in is clicks.
I should emphasise again the importance of not just using your chrono data. I have found that sometimes it’s very close and other times it’s a bit off. By off I mean I will go and do a low altitude drop test and the ballistics app recalculates the muzzle velocity required to achieve the measured trajectory. Sometimes the recalculated muzzle velocity is a fair few feet per second off the chrono average, like 30 or 40fps. But the validated trajectory from drop data always works. (If I cannot do a low altitude test then I make damn sure that I set the barometric pressure, altitude and temperature correctly. Don’t you just love smart phones.)
The other thing the drop test does is compensate for any differences in BC. I find overall that the ELD bullets actually fly better than what it says on the box.
These small differences in velocity add up, but by the time you end up with a number you are happy with and hits the little gong, you can tune your powder burn rate. This works really really well as long as you stay within the same powder lot. I think this is easier for us to do than it is for you guys because there is no limit to how much powder we can carry here. You fellas probably have a limit?
We are limited to a total max of 15Kg of powder including in ammo and primer explosives here in UK.
Dodgy I'd like to see an example of all the values an calculations to correct the powder burn rate all in one document. Have you got it on record? I'd like to give it a try and am a "monkey see, monkey do" kind of chap.
Ian
Dodgy I'd like to see an example of all the values an calculations to correct the powder burn rate all in one document. Have you got it on record? I'd like to give it a try and am a "monkey see, monkey do" kind of chap.
Ian
The part of this process that guys find hard to do, but it really is super critical, is the drop test. It can be difficult to find a clear line of sight in excess of 300 m. Doesn’t have to be in nice increments of 100 obviously but it is important that it is a good distance away. I like to do it at about 300 and 500m, I have an old door that I cart around and set up on metal stakes.
Morning Gents,
QL. Weighting Factors for different calibres are listed by Pierre Van Der Walt - 2016; he's done all the maths; I found this very useful.
link:- http://www.mamba-reloading.co.za/QL Weighting Factor.xls
Best Regards
Roy
QL. Weighting Factors for different calibres are listed by Pierre Van Der Walt - 2016; he's done all the maths; I found this very useful.
link:- http://www.mamba-reloading.co.za/QL Weighting Factor.xls
Best Regards
Roy
I'm learning that very thing now working up a load for my Mauser M12! Both Sako and Norma factory 120gr cartridges chrono at 2710fps (average) through the 20" barrel.
Alliant data for 6.5x55, 120gr bullet, using RL16 states the max powder load as 41grains. So, on the basis of "it'll be because of old 6.5 military rifles" I started my load at 40.7gr then went up in .3gr increments, 1 shot at a time over a chrono.
Have now reached 44.3gr giving 3735fps, with absolutely no signs whatsoever of excess pressure. I'm not going any higher as there is a node with 43.7gr at 2675fps.
So, in MY rifle (and I know all rifles behave slightly differently) the discrepancy between published maximum data and actual data is at least 3.7grains of powder!
Great stuff if you are a manufacturer of Powder or Bullets!
Last edited:
Smellydog
Well-Known Member
Absolutely. Except for hornet all my reloading ended up 2gn+ on book max.
It make sense really. They going to play it safe, not safe as in shooter safe, no safe from any blame. And so it goes...
if you are getting 3735 FPS with a 120 gr bullet you are massively over pressure
If you’re only getting 2675 with a 120 then a change of powder may be an idea
yes bore diameter, stating the obvious. Bigger hole, lower pressure slower velocity. not all barrels are equal.
Bullets also vary in diameter.
edi
Thank you I see my mistakeif you are getting 3735 FPS with a 120 gr bullet you are massively over pressure
If you’re only getting 2675 with a 120 then a change of powder may be an idea
. Should have written 2735fps.A change of powder is an option, but with 3 tubs of RL16 (it works well in my .243) I thought I'd give it a trial. I zero at 100m and measure the drop at 200m and 300m then dial the range on my 'scope. So 2675fps with a good case fill, good obturation and good groups will do as long as the Ballistic Tip expands out to 300m.
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