Home Forums Reloading Reloading Software Just got my QL up and running.......pretty cool!

nsaqam,

I like to run about 2,500 to 3,000 psi below SAAMI MAP, in general. I also don't use QL load data as gospel but as an additional source of reloading data. I've had some very accurate predictions come out of QL and some less so. But it's nice for a particular combination where actual tested data is a bit shallow. It can also help determine a theoretical "optimum powder" as Ken has pointed out (one of my favorite features as well).

Have fun with it.

Azar,

Thanks for that as that was where I've been running my pressure limits, 2 to 3K below MAP.
I'm relatively prudent about working up to max loads but I'll admit that I'm a fan of velocity and I'll generally try to wring the potential out of the cartridges I load for.
Sometimes I find that I have to back off a bit after I find pressure but more often I find acceptable accuracy up at the top.
Silly as it may be, and it is, I'll sacrifice 1/4 MOA for an extra 200fps. Mostly though, that has not been required.

I'm much more interested in down-range velocities than I am in muzzle velocities.

Muzzle velocities don't last. The faster a bullet starts, the faster it slows down.

Just for kicks, I just now ran the numbers� for one of my favorite cartridges with the same cartridge, same bullet, same everything except muzzle velocity and Pmax.

The bullets' BC is 0.473. The two muzzle velcities are 3,850 ft/sec and 3,500 ft/sec.

The difference of 350 ft/sec in muzzle velocities dwindles to 122 ft/sec at 500 yards and to 101 ft/sec at 1,000 yards.

The difference in Pmax is 60,000 lb/sq in. minus 50,000 lb/sq in. = 10,000 lb/sq in.

"Sacrificing" 350 ft/sec at the muzzle doesn't cost me that much out there where the bullets meet prairie dogs and coyotes.



�using Oehler's "Ballistic Explorer" software

OK, some specifics �

� Muzzle velocities were 3,850 and 3,500 ft/sec (slower is 90.9% of faster)

� Velocities at 500 yards were 2,752 and 2,630 ft/sec (slower is 95.6% of faster)

� Velocities at 1,000 yards were 2,009 and 1,908 ft/sec (slower is 95% of faster)

That's really interesting, Ken.

Thanks for pointing that out.

I just ran some numbers through the JBM Ballistic Calculator for the 162gr Amax using the Litz BC numbers and stopping at 1000 yards.

First load starting at 3000fps and the second at 2750fps.

At 100 the MV advantage is 244fps.
@100 it's 244fps.
@200 it's 237fps.
@300 it's 230fps.
@400 it's 223fps.
@500 it's 215fps.
@600 it's 208fps.
@700 it's 201fps.
@800 it's 196fps.
@900 it's 190fps.
@1000 it's 180fps.

Yes, the faster starting bullet loses velocity more quickly but it maintains a 200+fps advantage out to 700 yards.
That's significant to me, if only in my mind.

Sorry if this is a stupid question, but I've been playing
with QL and can't help but wonder -

which is more believable, the psi shown for the
charge weight I'm using, or the psi shown at the
velocities I'm actually seeing?

psi for velocities actually seen, assuming you have good reason to believe your chrono.

Are you adjusting QL to your fired case capacity?
Are you actually asking whether to modify Ba?

Thank you for the reply.

Yes, have weighed several fired cases level full of water
and adjusted (it was slight)

not sure about the last question? I believe I recognize you
are talking about the burn rate factor?

Correct.

Let me offer my experience with QL, so that you have some context against which to evaluate my original reply to you--

I find QL very entertaining. I enjoy the alternative powder suggestions it is able to provide, and I really appreciate having % case fill info. On a couple of occasions, it has been _dramatically_ far off in its predictions. Be careful with it; it can be very fun, but in no way would I use it as a replacement in isolation for pressure-tested data.

If you really want to get your money's worth for that software, I'd suggest you look into Chris Long's Optimum Barrel Time method for predicting an accuracy node based on QL's calculated barrel time. It doesn't always work this neatly but it has reduced the total of number of rounds I've fired before I set to tweaking seating depth to just a handful, sometimes as few as 12.


It also increases wind drift, shortens the max point blank range, shortens the danger space and magnifies the effect of shooter errors in range estimation and holdover.

And no matter how many figures the faster bullet loses, no matter how far they fly, it'll still be faster.

Worship of muzzle velocity commonly leads to the use of a lighter bullet for the sake of its higher muzzle velocity.

A few years back, I used Oehler's "Ballistic Explorer" to compare
(a) the justly respected .220 Swift factory load (presumably at 60,000 lb/sq in. or higher) with the 50-grain A-max
to
(b) my bigger .220 Howell with the 75-grain A-Max at a tad less than 50,000 lb/sq in.

Just reran the same comparison.

� at the muzzle
50-grain � 3,850 ft/sec
75-grain � 3,500 ft/sec (350 ft/sec slower}

� at 500 yards
50-grain � 2,282 ft/sec
75-grain � 2,630 ft/sec (348 ft/sec faster)

� at 1,000 yards
50-grain � 1,227 ft/sec
75-grain � 1,908 ft/sec (681 ft/sec faster)

That's right � at a tad past 200 yards, the "faster" 50-grain slows to the same down-range velocity as the "slower" 75-grain, and from that distance on farther down-range, the "slower" 75-grain is increasingly faster � with all the other benefits of its higher velocities and higher ballistic coefficient (energy, time of flight, wind deflection, trajectory) � despite its lower Pmax and MV.

Muzzle velocity, all by itself, does not tell all that there is to know about down-range performance.

Not for me.
I just want a higher MV with the same exact (heavy in my comparison above) bullet and I'm willing to drive my P-max up near SAAMI MAP to get that higher MV.

Wow that is good stuff XL and I just skimmed it.

I'll be downloading that tomorrow.

Dr. Howell, if you raised the Pmax to 63K on your .220 Howell, to what velocity could you drive that sleek 75 Amax?

Not enough to be worth it.

I just ran the numbers for the .220 Howell with a Pmax of 63000 using the 75 Amax out of a 24" barrel and I got a max MV 3464fps and 63Kpsi.
With a Pmax of 50K QL showed me a max MV of 3250fps.

So according to QL anyway it appears that 200+fps would be gained from a 13K increase in pressure.

Just some cogitating on my part and I fully realize that 50Kpsi max was part of the design parameters for this cartridge.

XL5, I've used QL in conjunction with the OBT hypothesis. It has been distinctly un-useful to me in that application. The Optimal Charge Weight (OCW) development method has been _dramatically_ more efficient and effective for me.

I will acknowledge that QL was much closer when I used single-base extruded powders (i.e. the old Canadian IMR-4198 in metal cans). With the powders I normally use, however, there is more than one powder-cartridge-bullet combination with which there is NOTHING I can do to make the various numbers square. So, QL (and therefore OBT) remains an entertaining diversion that is not used by me for such practicalities.