Quick load velocity way off

[Dubious]

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?

[Davey Boy]

My QL computes to 3160 MV.
Dave

[elkhunter11]

It's a calculation, not an actual measuring tool. I will trust my Magnetospeed over any calculation.

[Salavee]

Originally Posted by elkhunter11

It's a calculation, not an actual measuring tool. I will trust my Magnetospeed over any calculation.

Just curious as to why you would state that. A combiation of QL and a good chronograph trumps guessing your pressures off a chronograph alone.

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.

[elkhunter11]

Originally Posted by Salavee

Just curious as to why you would state that. A combiation of QL and a good chronograph trumps guessing your pressures off a chronograph alone.

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.

Using the OPs example, if Quickload calculated a velocity of 3133fps, and a proven chronograph such as a magnetospeed was reading an average of 3422fps, what would you estimate the actual velocity to be? Don't try and deflect the question or change the topic, just answer the question.

[Salavee]

Originally Posted by elkhunter11

Using the OPs example, if Quickload calculated a velocity of 3133fps, and a proven chronograph such as a magnetospeed was reading an average of 3422fps, what would you estimate the actual velocity to be? Don't try and deflect the question or change the topic, just answer the question.

The anwser is simple. If QL burn rates for a specific powder are modified to coincide with actual chronograph results for a specific load and rifle and kept for future reference they will be be almost dead- on for future loads and similar temperatures. You have the sequence backwards.

I think the OP showed that example for three different charge weights.

Fair 'nuff?

[Davey Boy]

here is the screenshot for it.

[Davey Boy]

Any Pressure signs as your velocity puts you over the safety limit, but who knows. No PS might be good to go.

[Dean2]

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.

[huntingfamily]

Originally Posted by Davey Boy

My QL computes to 3160 MV.
Dave

Mine as well. This is a low pressure/low velocity round.
I'd have a look at the labradar troubleshooting guide in this case.

[Salavee]

Originally Posted by huntingfamily

Mine as well. This is a low pressure/low velocity round.
I'd have a look at the labradar troubleshooting guide in this case.

The burn rates in QL are simply approximations. You have to adjust them for your particular load. That can only be done with a chronograph. Once the burn rate is adjusted to your MV average you will find QL to be extremely accurate for that load combo rifle and temperature.
As with any other Loading Manual predictions , start low and work up.

[Salavee]

Originally Posted by Salavee

The burn rates in QL are simply approximations. You have to adjust them for your particular load. That can only be done with a chronograph. Once the burn rate is adjusted to your MV average you will find QL to be extremely accurate for that load combo rifle and temperature.
As with any other Loading Manual predictions , start low and work up.

Adjusting the burn rate for H4831sc (ba) up to 4500 (Default is 4300) I show a MV of 3244. Pressure at 52139 psi. Probably very close.

[Dubious]

Originally Posted by Salavee

Adjusting the burn rate for H4831sc (ba) up to 4500 (Default is 4300) I show a MV of 3244. Pressure at 52139 psi. Probably very close.

you nailed it adjusting the burn rate of h4831sc to .5040 matches my recorded data for other charges I fired very closely.

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?

[gunluvr]

Originally Posted by Dubious

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?

Changing from one brass manufacturer to another can lead to a large discrepancy in velocity. With one of my 308 rifles I see a difference of well over 100 fps between Win brass and RP brass. So your results may be due to choice of brass (or size of your chamber if you're fireforming your AI from regular 25-06 brass).