Novice Quickload help with tuning the powder vs velocity

[AnthonyC]

Hi - I have searched both the forum and google with no success.

I have just finally bought Quickload and have read a fair amount on using it prior.

I have entered all my info for my 270 (lengths, capacity etc), per long family website I have also adjust the burn rate factor of the powder (H4831SC)

So with;
59.5gr chrono’d velocity is 3050fps (halfway between the nodes) (no wonder I’m getting inconsistent group sizes!)
60gr chrono’d velocity is 3110fps

If I adjust Quickload to suit the 1st load (59.5 @3050) it will only hit 3080fps for the second (not 3100).

Any ideas? I’m really hoping its a reasonable easy adjustment.

Thanks very much for any help.

 

[jimbires]

here is a link to a thread on the " weighting factor " adjustment . I've struggled with RL26 in quickload , but this weighting factor seems to bring things into believable outputs .

the first link in the third reply gives you a PDF chart .

https://www.longrangehunting.com/threads/quickload-over-bore-weighting-factor-formula.136923/

 

[MSS]

Wow. Totally reading up on this. Furthest I’ve gone is adjust ba factor.

 

[texasbilly]

I am intrigued by your questions and procedure. Are you trying to establish a scientific formula to solve your ballistics problem? If so, how do you factor in all of the variables of ballistics, rifle characteristics, shooter skills, temperature, etc., etc. As I stated, I am intrigued and interested.

 

[Bart B.]

Regarding the Long theory on barrel frequencies they vibrate at, he says:

The basic resonant (beam bending or “ruler on the edge of the desk”) mode of a cantilevered barrel (beam) made of steel at our typical lengths and diameters is on the order of 500 to 1000 Hz, give or take.

The average mechanical engineer in material rigidity work will use 4th order moment of inertia calculations to learn rifle barrel basic resonant frequencies they vibrate at are only a few to several dozen Hz. Long's theories are not based on realities. If your 270 barrel is a standard sporter profile, I can calculate its approximate resonant frequency with software given to me.

Good info on barrel vibration frequencies, mode 4 shows muzzle diameter change frequency in "Barrel harmonic movie" in:

http://www.varmintal.com/ahunt.htm

Regarding bore capacity.....

http://forum.accurateshooter.com/threads/300-norma-mag-barrel-life.3943664/#post-37138217

It will vary a little with powder heat index.

Your rifle and ammo won't produce the numbers Quickload does. Different barrel and component lot numbers between your stuff and what Quickload used. A 150 fps difference is not unheard of. Barrel times will be different.

Therefore, I suggest you try 3 or 4 loads one grain apart and use the one whose10-shot group is smallest.

 

[Zero333]

I LOVE Quickload.

 

[Murray Brook]

Hi - I have searched both the forum and google with no success.

I have just finally bought Quickload and have read a fair amount on using it prior.

I have entered all my info for my 270 (lengths, capacity etc), per long family website I have also adjust the burn rate factor of the powder (H4831SC)

So with;
59.5gr chrono’d velocity is 3050fps (halfway between the nodes) (no wonder I’m getting inconsistent group sizes!)
60gr chrono’d velocity is 3110fps

If I adjust Quickload to suit the 1st load (59.5 @3050) it will only hit 3080fps for the second (not 3100).

Any ideas? I’m really hoping its a reasonable easy adjustment.

Thanks very much for any help.

I believe your vel of 3080 is about as close as this program will get you.Remember there are certain factors that affect velocity that quickload does not take into account, The primer is one. Different make or standard vs magnum could make up for the 20 ft/sec. There are also discrepances in the vel the chronograph gives.