Quickload underestimating velocity

[timelinex]

I've been playing with quickload and its underestimating my velocities by alot. My setup is a 110ba using 92gr of retumbo (92.8 previously , lapua brass, 215m primers and 300 gr OTM bergers jammed into the lands. I get a velocity of 2805 from my chrono, and this velocity works well to estimate my drop at a mile. I'm fairly certain of the velocity as I have measured it on my CED m2 on multiple occasions and a friends oehler.

I took the time and input all my own measurements of case capacity and etc.. Maybe someone can check it over.



Anyways, it gives me an estimated velocity of 2672 which is pretty far off from 2805. The estimated pressure of 62k doesn't seem to far off as its showing it as a hot load, but not MAX hot. Even adjusting the starting pressure to theoretically set the pressure to way over saami max, the velocity never gets into the 2800's.

What am I doing wrong here?

 

[timelinex]

As for my 308, its funny that it estimates my velocity pretty accurately, however tells me that its a compressed load and 4k over MAX pressure. It is neither of those things, its a fairly high pressure load but there's still alot of room in the case when I shake it.

Something isn't adding up....

 

[eagernoskill]

Quickload

I've been playing with quickload and its underestimating my velocities by alot. My setup is a 110ba using 92gr of retumbo (92.8 previously , lapua brass, 215m primers and 300 gr OTM bergers jammed into the lands. I get a velocity of 2805 from my chrono, and this velocity works well to estimate my drop at a mile. I'm fairly certain of the velocity as I have measured it on my CED m2 on multiple occasions and a friends oehler.
I took the time and input all my own measurements of case capacity and etc.. Maybe someone can check it over.
View attachment 3597
Anyways, it gives me an estimated velocity of 2672 which is pretty far off from 2805. The estimated pressure of 62k doesn't seem to far off as its showing it as a hot load, but not MAX hot. Even adjusting the starting pressure to theoretically set the pressure to way over saami max, the velocity never gets into the 2800's.
What am I doing wrong here?

I replicated as best I could the load you have - Had to use the 300 Berger Hybrid but changed it.
I get 51,010 psi for 2,596 velocity I did notice my "Shot Initiation Pressure was 3,626 - unlike your which was 10,825 in the jpeg

The other thing I noted that the default H20 capacity for the 338 is 108 and when I did that instead of the 116.6.
you have I got 61,470 psi for 2,704 fps

When I loaded the default 300 Berger I noted the default Cartridge Length was 3.681 you have
The weighting factor you gave is 0.55

So I varied it as follows
1. Use default H20 case capacity
2. Check cartrdige Length
3. Vary the Weighting factor
4. Adjusted bullet length (to replicate you bullet)
5. Shot Initiation pressure

.. and and allow some "chrono" tolerance of say 20 fps

Using the above I got to 2,757 at 64,969 psi.

Remember the exact performance is determined by the chamber and barrel as well.

 

[X-fan]

Different bullets types, but of the same weight give different velocities....Same goes for barrels and chambers...They all make a difference.
Velocity and pressure however are inseparably connected...you can not have one without the other.

Berger list a max of 89.5grs of Retumbo for 2680fps. At 2800fps you are way over 60Kpsi..whether you can see the pressure of not or not does not change that is is there.
My rifle shoots the 300SMK over 94grs Retumbo for 2690fps for an averaged 58Kpsi pressure (I have pressure testing gear).

Other than some early prototypes I have not shot the 300OTM so I can't offer much more boots on the ground help.
I do assure you that you have all the pressure that you want..and then some.

Plug 2800fps in to your program and see what it tells you....70-75Kpsi I bet?

 

[timelinex]

I replicated as best I could the load you have - Had to use the 300 Berger Hybrid but changed it.
I get 51,010 psi for 2,596 velocity I did notice my "Shot Initiation Pressure was 3,626 - unlike your which was 10,825 in the jpeg

The other thing I noted that the default H20 capacity for the 338 is 108 and when I did that instead of the 116.6.
you have I got 61,470 psi for 2,704 fps

When I loaded the default 300 Berger I noted the default Cartridge Length was 3.681 you have
The weighting factor you gave is 0.55

So I varied it as follows
1. Use default H20 case capacity
2. Check cartrdige Length
3. Vary the Weighting factor
4. Adjusted bullet length (to replicate you bullet)
5. Shot Initiation pressure

.. and and allow some "chrono" tolerance of say 20 fps

Using the above I got to 2,757 at 64,969 psi.

Remember the exact performance is determined by the chamber and barrel as well.

The thing is, I measured everything an the data you see on there is what I actually measured! So it should apply to me. The only thing that isn't measured and I used as instructed was the weighting factor and the shot initial pressure.

Different bullets types, but of the same weight give different velocities....Same goes for barrels and chambers...They all make a difference.
Velocity and pressure however are inseparably connected...you can not have one without the other.

Berger list a max of 89.5grs of Retumbo for 2680fps. At 2800fps you are way over 60Kpsi..whether you can see the pressure of not or not does not change that is is there.
My rifle shoots the 300SMK over 94grs Retumbo for 2690fps for an averaged 58Kpsi pressure (I have pressure testing gear).

Other than some early prototypes I have not shot the 300OTM so I can't offer much more boots on the ground help.
I do assure you that you have all the pressure that you want..and then some.

Plug 2800fps in to your program and see what it tells you....70-75Kpsi I bet?

Everyone I know uses 92-94 gr of retumbo behind the 300gr Bergers.... I'm not saying that doesn't mean we are all over 'book' pressure, but rather that the platform allows it safely.

 

[One-Eyed Jack]

Three suggestions:

1. The cartridge inputs should be actual measurements of your round, made as accurately as you can. Don't use the nominal values if you can measure your cartridge.
2. Some barrels have less friction than the nominal friction model, you can adjust the model to get closer to your chrono measurement. In my experience, a fast 308 barrel might give 50fps more MV than QL with accurate inputs.
3. There is a possibility that the powder you are using has several percent more or less energy than the nominal power burning model. Varget, in particular, has been noted to have some variability in the past, although I don't know whether Hodgdon has made it more consistently in the last few years.

I've found QL to be remarkably accurate or close, considering the number of variables that affect MV. Are you using the powder update disk? I don't know if the update would affect your calculated result, but it's worth the price to get the disk.

 

[MALLARD]

Personally I would ignore pressure and focus on tweaking burn rate factor to match the velocity of your empirical results. I have a machine that measures pressure and I never could get the pressures from my machine to match quickload. I believe this is the result of the inadequacies of quickload.

 

[timelinex]

So what values should I tweak to match my velocity to the ql velocities? Should I play with the weighting factor or powder numbers? Mallard, I'll try tweaking the burn rate factor. I've read you can play with all of them 5% to make it work, but I would deff need to change it by more than that to make up the 100+ fps. I had to adjust the burn rate 20% to get it up to 2800, and the pressure is through the roof at 85k.

 

[timelinex]

I have had two charges that I have worked with in the past. 92.8 previously and 92gr now. 92.8gr showed good accuracy, but I decided to try lower as it was a pretty hot load. I found that 92gr showed just as good accuracy and I only sacrificed 15 FPS. I tried to play around with the OBT formula, to find my nodes according to that theory. I had an interesting find.By adjusting the burn rate by 5%, according to quickload, I was at within .5 a % of a node at both charges and the velocity only differed by about 15fps between the two charges, just like in real life. The only discrepancy is its showing exactly 100fps less.

 

[jfields]

Very interesting stuff! I too am using 92 grains of Retumbo and the 300 OTM Hybrid, although I am not even close to the lands at 3.69 OAL. This is for my 110BA, as well. I have played with QL ad nauseum trying to get usable results to no avail. The part that bothers me the most is the difference between the default H2O capacity and my measurements. I have weighed dozens of cases, and they always measure within .1 of 116 grains water capacity. The default is 108! That seems like a pretty big difference to me. Am I wrong?

-Shaky

 

[timelinex]

Very interesting stuff! I too am using 92 grains of Retumbo and the 300 OTM Hybrid, although I am not even close to the lands at 3.69 OAL. This is for my 110BA, as well. I have played with QL ad nauseum trying to get usable results to no avail. The part that bothers me the most is the difference between the default H2O capacity and my measurements. I have weighed dozens of cases, and they always measure within .1 of 116 grains water capacity. The default is 108! That seems like a pretty big difference to me. Am I wrong?

-Shaky

Your not alone, I'm at 116gr as well. Have you measured your velocity, it would be interesting to see what speed yours is coming out at. However, jammed into the lands or mag length rounds make a big difference velocity wise (and accuracy wise for me).

I gotta say, I'm pretty disappointed with QuickLoad. I know its garbage in garbage out, but I've put in everything as accurately as possible. I also understand that barrels make a difference. However the allure of the program is to accurately predict data, if it doesn't do this, for whatever reason, then its just a good way to waste some time. I suppose the only good thing is that it might help you find 'compatible' powders for a cartridge, however thats information is plastered all over the internet.

 

[jfields]

My velocity is 2750 with 92 grains of Retumbo at 3.69 OAL. This is checked with a Magnetospeed chronograph. I Chronoed five shots that had an ES of 5 FPS! That's the best I have personally ever seen. If I could get photobucket to work, I would post a pick of a three shot group shot at 300 yards that measured .668"! I was checking a few different loads because I just got my new AAC Titan and I was sure accuracy and POI would change. The can also seems to bump up the pressure a bit. I moved from 93 grains to 92 and would still stick the occasional case if I was shooting quickly. As long as I let things cool down periodically, I had no failures to extract.

What OAL are you using, Timeline?

I got photbucket to work in another browser.

-Shaky

 

[Heman]

Weighting factor

Double check the case dimensions and see what weighting factor it will calculate for you. Some of the stock values are way off for example the .223 should be .51 I think and default is .60 or somthing. The .55 value you show may be close but have it recalculate that for you.

 

[timelinex]

My velocity is 2750 with 92 grains of Retumbo at 3.69 OAL. This is checked with a Magnetospeed chronograph. I Chronoed five shots that had an ES of 5 FPS! That's the best I have personally ever seen. If I could get photobucket to work, I would post a pick of a three shot group shot at 300 yards that measured .668"! I was checking a few different loads because I just got my new AAC Titan and I was sure accuracy and POI would change. The can also seems to bump up the pressure a bit. I moved from 93 grains to 92 and would still stick the occasional case if I was shooting quickly. As long as I let things cool down periodically, I had no failures to extract.

What OAL are you using, Timeline?


I got photbucket to work in another browser.

-Shaky

My OAL is around 3.826, so considerably longer. This works out to be about .015 jammed into the lands. I have to single feed them , which is fine by me considering I don't shoot it any faster than I can manually feed anyways. Thats great that you get such low ES's, I'm glad im not the only one. Jamming them into the lands, I get anywhere between an ES of 1 and 8 for 5 shot groups (Yes 1!). To be fair, thats much lower than the proposed accuracy of our chrono's, so can't be too sure how accurate those ES's are. However when I backed them out to magazine length, my ES's jumped to 20-30 fps.... so I believe it.

I'm waiting on a 338BA thunderbeast can, so I will have to do a bit of load development for that soon.

Its good to see that you are getting similar results as me, and its not just my testing that showed such high velocities. Your 2750 is about right, considering jamming the bullet into the lands buys some velocity and pressure. I'm impressed with the velocities that these 110ba's produce. My friends surgeon and AI are both producing between 2725-2750 and its closer to the max pressure.

 

[timelinex]

Double check the case dimensions and see what weighting factor it will calculate for you. Some of the stock values are way off for example the .223 should be .51 I think and default is .60 or somthing. The .55 value you show may be close but have it recalculate that for you.

Are you talking about the cross sectional bore diameter? I've already measured and inputted my specific case length and capacity. How do I get it to calculate the weighting factor. I only see an option to put my own number in for it and hovering over it provides recommendations.