Lower than expected velocity

[4xtrak.chmp]

Newbie here, new to reloading,new chronograph user.
According to the hornady reloading info a 147gr.ELD 6.5 creedmoor loaded with 41.2 gr. of IMR 4831 should have a MV of 2600 fps. I am getting an average of 2536.
With this same data loaded into the Quick Load program along with Maximum case capacity overflow in h2o at 53.4 and a barrel length of 26 inches it thinks my velocity should be 2710.
My chronograph is 15 feet away from the muzzle and even though it is entry model( caldwell) I do believe it is giving me realistic readings. I have shot some factory rounds and several rimfire rounds through it that make me trust what it is telling me.
So here is my concern. I am ready to start loading my rounds closer to my lands and I need to believe my quick load program so i can trust the pressure numbers more importantly than the velocity numbers. If in reality my MV is 175 fps slower than what QL is then i wonder where my pressures are really at? I understand there are lot of variables that go in to that program but that seems pretty far off. Am I concerned over nothing? Could use some advice from more experienced loaders.

 

[Steel head]

I’m not surprised.
H4831 is a fantastic powder but it’s not optimal at all for 6.5CM.
You just can’t stuff enough of it in to get up to speed.


H4350
IMR4451
R16 (especially if you want speed)
These should get you to 2700 or beyond.
I get 2800 with my 260 with 147’s using R16.

 

[Cascade Hemi]

Velocity begins dropping as soon as the bullet exits the barrel. Predicted velocities are from the muzzle so velocities 15' away at your chronograph will be lower. You're probably closer to 2550 at the muzzle which isn't very far off of the data.

There is always variation between predicted velocity and measured velocity; if you don't have pressure signs and accuracy allows it, you have some case capacity to continue working up. I plugged your information into QL and got a prediction of 2609fps. Your load looks pretty mild and should to have some room before reaching max pressure. IMR4831 loaded to 2.80" will compress around 42.5gr.

It may be helpful to start by doing a simple single round pressure ladder in .2gr increments until you reach case capacity or see pressure signs. Once you find your limits then back down and do your work up knowing you hard stops.

 

[spife7980]

For a new loader I would take the quick load with a grain of salt, to get really good data from it youll need to measure case capacities, true up the powder profile etc, usually thats bit advanced for a new reloader who just wants to make something functional and safe. And each price of brass bullet etc can vary which make getting solid data even tougher. Not impossible, there is just a bit more to it than simply entering data like its a generic reloading book.

So just like with a ballistic calculator you need to get all the good data up and then true quickload to match.

It may be helpful to start by doing a simple single round pressure ladder in .2gr increments until you reach case capacity or see pressure signs. Once you find your limits then back down and do your work up knowing your hard stops.

I would start here to get real world tangible results and work from there. People have been successfully loading without computers for a long long time.

 

[4xtrak.chmp]

I appreciate the replies. I will take all the suggestions and go from there . I was hoping that i was over thinking things. Just don't wanna get myself in trouble when I start lengthening the cases. The COL i should say.

This forum seems to be loaded with info/tips and very knowledgeable people on the whole process. I look forward to learning about everything as I go along.

 

[918v]

QL is a specialized tool that requires you to know what you’re doing. Did you measure your actual fired case volume? Did you adjust the burning rate in QL to match your chrono velocity?

 

[straightshooter1]

Newbie here, new to reloading,new chronograph user.
According to the hornady reloading info a 147gr.ELD 6.5 creedmoor loaded with 41.2 gr. of IMR 4831 should have a MV of 2600 fps. I am getting an average of 2536.
With this same data loaded into the Quick Load program along with Maximum case capacity overflow in h2o at 53.4 and a barrel length of 26 inches it thinks my velocity should be 2710.
My chronograph is 15 feet away from the muzzle and even though it is entry model( caldwell) I do believe it is giving me realistic readings. I have shot some factory rounds and several rimfire rounds through it that make me trust what it is telling me.
So here is my concern. I am ready to start loading my rounds closer to my lands and I need to believe my quick load program so i can trust the pressure numbers more importantly than the velocity numbers. If in reality my MV is 175 fps slower than what QL is then i wonder where my pressures are really at? I understand there are lot of variables that go in to that program but that seems pretty far off. Am I concerned over nothing? Could use some advice from more experienced loaders.

As mentioned in a previous post, your Chrono is not measuring true MV since it's 15ft away. So, you add that to your chrono that of itself is not giving you a particularly accurate reading and so you can be off by quite a bit on what your actual MV is. For QL, powder burn rate is not uniform from one lot to another (even at the same temperature), so this is often adjusted by matching your actual MV measurements to QL's calculations (assuming you have all the other variables input correctly).

So, with all these variables, it's best to just start off by focusing what you're getting on paper. You can simply
increase your COAL by increments until you touch the lands to see where length works for you. Just pay attention to any pressure signs and record all you loading and chrono info to build your data base for future reference. When you've accumulated a bunch of data, you'll then be better at using tools like QL for future load development.

PS: would highly recommend getting a MagnetoSpeed or LabRadar chrono if you can afford it. This way you'll get actual MV numbers that are pretty accurate.

 

[TxWelder35]

I’m not surprised.
H4831 is a fantastic powder but it’s not optimal at all for 6.5CM.
You just can’t stuff enough of it in to get up to speed.


H4350
IMR4451
R16 (especially if you want speed)
These should get you to 2700 or beyond.
I get 2800 with my 260 with 147’s using R16.

This. I would also suggest a different powder. Leaving a lot of capability on the table using that powder. You will easily gain 200fps with a better burn rate

 

[DownhillFromHere]

Your muzzle velocity 15 feet out will be less than 10fps lower than at the muzzle.

I say this based on LabRadar-measured velocities of the 147gr ELD-M, which, in the series I looked at, the 2773fps MV dropped an average of 14fps from muzzle to 10 yards, 34fps@25 yards (LabRadar can be programmed to report, in addition to MV, five downrange velocities as far as the unit can "see" the bullet).

I had a Caldwell chrono before I got the LR. Other than being a pita to use, its accuracy was fine. Even after I put a 9mm bullet through the top of the display screen, although it did stop "talking" to my phone afterward.

 

[4xtrak.chmp]

QL is a specialized tool that requires you to know what you’re doing. Did you measure your actual fired case volume? Did you adjust the burning rate in QL to match your chrono velocity?

I did measure the case volume but I dont know how to adjust the burn rate.

 

[4xtrak.chmp]

I just did get my hands on some h4350 last week which is why i didn't try it in the first place...hard to find at the moment. Trying that is in the near future.

 

[straightshooter1]

I did measure the case volume but I dont know how to adjust the burn rate.

Click on the icon to the right of it (kJ/jg) then you can change the burn rate as well as the Temperature above "Apply& Calc"

 

[918v]

I did measure the case volume but I dont know how to adjust the burn rate.

Click on the little icon in the upper left corner of the powder data window, then click into the Burning Rate Factor box and change it incrementally until your velocity lines up with your chrono. IMR 4831 is .4421. Change it to .4521, .4621, etc

 

[4xtrak.chmp]

I will check that out... I surely do thank you for the info

 

[4xtrak.chmp]

I had to go from .4421 to .4021 to get it inline with my numbers! I wasn't aware that I needed to do that but thats awesome you guys taught me that Thankyou

 

[straightshooter1]

Click on the little icon in the upper left corner of the powder data window, then click into the Burning Rate Factor box and change it incrementally until your velocity lines up with your chrono. IMR 4831 is .4421. Change it to .4521, .4621, etc View attachment 7328949

Hmmm??? Interesting that the icon is at a different location on your QL app.

 

[straightshooter1]

I had to go from .4421 to .4021 to get it inline with my numbers! I wasn't aware that I needed to do that but thats awesome you guys taught me that Thankyou

You might find the attached of some use as you go to select powders to use.