QuickLoad vs Bullet Manufacturers Loading Data Delima

[Gordie]

I just purchased QuickLoad. Using Varget with a 155.5 Berger bullet in .308 caliber, I can load up to 47.1 grains without going over the line into "Dangerous Load-Do Not Use" using QuickLoad. The Berger reloading data sent to me by Sinclair, who acts as their technical staff, shows the max load as 44.6 grains. That's a difference of 2.5 grains. I used the QuickLoad data, starting 10% below 47.1 grains to see if any pressure was put on the case as well as the primer. When I got up to the 47.1 cartridges, I had no pressure problems (the calculated pressure is 59,312 psi at 47.1 grains).

My question is this-why is Berger data so low? Am I OK to use QuickLoad to figure all my charge weights in the future? Help!

Gordie

 

[918v]

They may have used heavier brass with less internal capacity. I can tell you that 44.4grs of varget under a 168gr A-Max is perfectly safe in a Winchester case, so 44.6grs under a 155 is kinda light unless they used FC or some military flavor.

 

[SilentVectorX]

They may have used heavier brass with less internal capacity. I can tell you that 44.4grs of varget under a 168gr A-Max is perfectly safe in a Winchester case, so 44.6grs under a 155 is kinda light unless they used FC or some military flavor.

Exactly! You HAVE to get an accurate measure of your internal case capacity for QL to really be accurate.

Make sure when you measure weight in grains of water capacity, you:
-Use a fired case from the exact gun you will be using
-Trim and measure the case, plug the info into your case specs in QL
-Ensure there's no tumbling media or debris in the case
-Fill to a domed-up meniscus but don't actually overflow the case mouth
-Measure at least 5-10 cases, your call on if you want to use the minimum (worst case, higher pressure) value or average ICC for your final load data

 

[MEHavey]

From Hodgdon's site:

155 GR. SIE HPBT Varget .308" 2.775"OAL
MIN:44.0gr 2,759fps 41,300 CUP
MAX: 47.0(Compressed) 2,909fps 49,400 CUP

(Note the CUP is not psi, and that Hodgdon is considered the high-end of pressure standards). QL is pretty good on predicting bottleneck cartridge performance, but it needs good input (case capapacity & OAL matter).

Now you see why multiple data sources helps in judging where "truth" (in quotes) lies. (no pun intended) and why a chronogrpah helps even more.

 

[243winxb]

My question is this-why is Berger data so low? Am I OK to use QuickLoad to figure all my charge weights in the future?

The difference in bullet bearing surface & jacket thickness will make different pressures. Use a starting load and work up as always using a firearm, not a program.

WARNING: QuickLOAD is a computer simulation of centerfire cartridge performance. YOU MUST NEVER just "plug in the numbers" and use QuickLOAD's output for a load recipe. That is foolish and dangerous. There are many reasons why the data QuickLOAD generates may not be safe in YOUR gun. Before loading live ammunition, you should always check with the powder-makers' most recent load data. In fact, you should check multiple sources if possible, and consult with individuals who actually load for that cartridge. Sierra Bullets offers free load maps which, in general, are fairly conservative. Even when using manufacturers' load data, start 10% low and work up. Differences in brass, primer brand, and seating depth can make huge differences in pressure. Always reload conservatively and always double- and triple-check QuickLOAD's output against reliable load data supplied by the powder-makers.

http://www.6mmbr.com/quickload.html

 

[MEHavey]

...QuickLoad. Using Varget with a 155.5 Berger bullet in .308 caliber, I can load up to 47.1 grains without going over the line ...calculated pressure is 59,312 psi at 47.1 grains).

Notwithstanding my comments above (which favor Quickload for understanding what's happening under different conditions), I get different numbers:



Where in what you see do we have different assumptions?

~~~~~~~~~~~

BREAK, BREAK: QuickLoad will also expose dramatic changes in pressures for different bullet designs. Hodgdon's data is for a Sierra 155 HPBT. That is a very different bullet design from Berger's 155.5 MT-BT #30416. QL predicts 58,500psi for the Sierra bullet, considerably different from Berger's which appears to be 7,000psi higher.

 

[243winxb]

Comparing CUP to PSI, how does that work? Meaningless?

 

[RidgwayCO]

Some questions:

1) Did you chronograph your test loads in working up to 47.1gr?
2) If so, how does their velocity compare to what QuickLOAD predicted? If not, how do you know if QuickLOAD is even in the ballpark?
3) Did you enter your actual measured case volume into the program?
4) Was the powder compressed? QL predicts 110% of case capacity, which should give significant compression.

These are all areas that need your attention when working with QuickLOAD.

 

[ranger335v]

"My question is this-why is Berger data so low? Am I OK to use QuickLoad to figure all my charge weights in the future? Help!"

I can help. Use Quickload, etc, when it matches load book data. When there's a difference, follow the book. And that means use ALL of the book, especially the part where it says, "start low and work up slowly to max unless you see excess pressure signs sooner." Do that and you will be safe. Ignore that and no one will be safe.

Anyone attempting to "pressure test" reloads by computer projections will also be deluded by computer projections saying human's exhaling CO2 is melting the polar ice caps. In both instances, the computers are interesting to play with but if you want to know what the heck is going on, do the field experiments neccessary, computer projections are just that and no more.

 

[LubeckTech]

The thing to remember about QuickLoad is that it is NOT a loading manual but it IS a very valuable tool not only for load development but for learning about reloading. It is an invaluable tool for powder selection and can often answer the question why don't I see a load for that bullet-powder-cartridge combination. Safely reloading rifle cartridges is requires great care and in addition to QuickLoad you need a good manual or two and they may not always agree. Cartridge capacity can be a big factor as it effects pressure so what is a safe load in one brand of brass may not necessairily be safe in another as case thichnesses can vary. For safe and consistant rifle loads it is a good Idea to sort brass by headstamp or measure and sort brass by capacity - that may be going a bit far but it can't hurt .Just because QuickLoad says a load generates pressure well below the maximum pressure does not mean the load is safe. It is important to observe the MINIMUM load as well as the maximum loads in the manual. Too light a load with the wrong bullet in the wrong case can cause a pressure spike that can destroy a gun and possibly injure the shooter and/or bystanders.

 

[Clark]

My Varget gets a loose primer pocket with a 308 type case head [243] at Quickload 77kpsi while there is no extractor groove expansion at all that I can measure at Quickload 72kpsi.

This pressure prediction is consistent with other experiments that were chronographed, and so means when I shoot it over a chronograph, the predicted velocity and the measured velocity will be very close.

Contrast that with my jug of H4350, that is always a couple grains wimpier than the QL library of constants for H4350 would predict.

Of course, the military 308 brass has room for 4 gr less powder than the commercial brass, and that must go into QL.

 

[caster44]

Quick Load issues

I also have quick Load and have found several instances where that data
does not agree with my real world facts. About half the time this can be resolved by corrections in bullet seating depth. Case volume seams to be part
of most of these issues. Recently I have been on a project to develop loads
for Alliant 2400 in .45 ACP +P revolver. There is almost no info available to start a project like this. Using Quick Load I completed this project in about a
week. I am very happy with the results.

 

[Gordie]

Thanks for the response to my inquiry. I'll try to answer your questions below.
1. I started 10% below the 47.1 and looked at 10 different cases and primers (1% increments and 5 cases at each level) for pressure problems.
2. I measured 12 cases with water and came up with an average capacity of 56.36 grains. The cases were trimmed and prefired in my rifle.
3. The 12 case lengths averaged 2.008"
4. The average actual cartridge length is 2.894"
5. My barrel length is 22.75"
6. Measured actual average bullet length is 1.240"
7. Chronograph velocity was 2933fps. Quickload estimate showed 2822 (?)
8. Actual average C.O.A.L. is 2.894"
I hope this gives you enough information for those who want to check my calculations and those who wanted to know what I did to set this up. If anyone has any additional information they need to know, let me know and I will respond tonight. Thanks for your interest

Regards,

Gordie

 

[rcmodel]

Quickload data is a computer generated estimate.

Reloading manual data is a scientifically tested fact from actual pressure testing in a pressure barrel.

Take your pick.

rc

 

[243winxb]

Gordie, you seem to have a good handle on the process of reloading. Can't have to many tools or information. Where i see some handloader get in trouble, is this. Loading 1 brand of bullet at a maximum powder charge, then substituting another bullet brand, same weight, without reducing the maximum charge & working up. Same might be said of any component.

 

[918v]

Pressure barrels are not your firearm. Speer's, Hornady's, and Sierra's test firearms are not your firearms. Always work-up from min to max. Use QL to see what's going on inside a theoretical scenario, but not as a max pressure gauge.

 

[RidgwayCO]

Gordie, I always get concerned when a load outperforms a QuickLOAD computation. The reason is because velocity has to result from pressure, and higher velocity indicates higher pressure. To get your 2933 fps, QuickLOAD says you need 67,391 psi (from 49.02 gr of Varget) from your 22.75" barrel. My suggestion is to back off the gas pedal some, to 2800 fps or less...

Plus, to concur with what rcmodel said above, Hornady lists a maximum of 44.9gr of Varget with a 155gr bullet. This results in about 2700 fps from a 22" barrel. I'd be very hesitant to accept a higher velocity based strictly on QuickLOAD. YMMV.

 

[ollifl]

Surprisingly, nobody said lawyers and liability....

 

[Clark]

..Reloading manual data is a scientifically tested fact..
rc

This is why I don't drink coffee over my keyboard.

 

[steve4102]

Not sure what you pluged into your QL program , but my calculations puts your 47gr Varget load at over 65K psi.

Cartridge : .308 Win.
Bullet : .308, 155.5, Berger M T BT
Cartridge O.A.L. L6: 2.800 inch or 71.12 mm
Barrel Length : 5.0 inch or 127.0 mm
Powder : Hodgdon VARGET

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 88 37.60 1267 555 33695 25036 59.1 0.599
-18.0 90 38.54 1306 589 35988 26398 60.7 0.581
-16.0 92 39.48 1345 625 38438 27806 62.3 0.562
-14.0 95 40.42 1386 663 41061 29260 63.9 0.542
-12.0 97 41.36 1428 704 43868 30757 65.5 0.523
-10.0 99 42.30 1471 747 46875 32299 67.2 0.504
-08.0 101 43.24 1515 792 50095 33880 68.8 0.486
-06.0 103 44.18 1560 841 53523 35502 70.5 0.469 ! Near Maximum !
-04.0 106 45.12 1607 892 57192 37159 72.2 0.452 ! Near Maximum !
-02.0 108 46.06 1655 946 61134 38851 73.9 0.436 !DANGEROUS LOAD-DO NOT USE!
+00.0 110 47.00 1704 1002 65372 40574 75.5 0.420 !DANGEROUS LOAD-DO NOT USE!
+02.0 112 47.94 1754 1063 69936 42324 77.2 0.405 !DANGEROUS LOAD-DO NOT USE!
+04.0 114 48.88 1806 1126 74859 44095 78.9 0.391 !DANGEROUS LOAD-DO NOT USE!
+06.0 117 49.82 1859 1194 80176 45886 80.5 0.377 !DANGEROUS LOAD-DO NOT USE!
+08.0 119 50.76 1914 1265 85931 47691 82.1 0.363 !DANGEROUS LOAD-DO NOT USE!
+10.0 121 51.70 1970 1340 92171 49500 83.7 0.349 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 110 47.00 1830 1157 77063 44984 84.3 0.386 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 110 47.00 1566 847 53976 35278 65.4 0.463 ! Near Maximum !

 

[MEHavey]

QuickLoad is absolutely dependent upon the data it is fed. Given Gordie's data in post #13 above (slightly larger case capacity/slightly longer COAL/slightly shorter barrel**) QL's pressure drops to 59,600... just under Max.... but velocity also drops to 2,825fps.

Doing the velocity-ratio-cubed thing, that brings the effective/probable pressure back up to ~66,000psi+. That's way over the edge, and only a superior lot of brass and/or lower temperature day is helping us out.

This is another case where "...the rest of the story..." is best available by looking at what QuickLoad is trying to tell us.***

~~~~~~~~~~~~~~~~~~~~~~~

**That "22.75-inch barrel" is really the measure from the receiver ring to the muzzle?

*** QL also tells me that for "standard" brass volumes and "standard" COALs, Sinclair's recommended 44.6gr Varget/Berger 155.5 combo puts out 55,200psi. This is the lawyer-safe 90% loadout.

 

[Gordie]

Thanks for the additional response since my #13 comments. I wish I knew how to post my information like MEEHAVEY did on #6 above so you could critique my data. Also, I measured my barrel by imputing a dowel in the muzzle until it was stopped by the front of the bolt. I measured the distance the dowel was in the barrel. I did have the end cut off to get rid of the muzzle break. By the way, the range temperature was at 89.5 F which could account for a little higher pressure. Ant additional thoughts? Thanks for your input.

Regards,

Gordie

 

[918v]

Surprisingly, nobody said lawyers and liability....

It's not so much that as premature wear and tear. I want my gun to last forever, so I stay south of published max. There are certain loads, i.e. max charges of Herco under 124gr bullets that will safely give you 1300 FPS from a 4" barrel, but wear out the throat in a short order. Many people don't understand that with increased velocity comes increased recoil and battering of the frame and slide. They don't change springs. While the maximum safe load may be alot higher than what they publish, that very same load will quickly beat your gun to death if you don't tame it with a comp or a heavier recoil spring.

 

[Clark]

Yesterday, 08:57 PM #23
918v

Surprisingly, nobody said lawyers and liability....
It's not so much that as premature wear and tear. I want my gun to last forever, so I stay south of published max. There are certain loads, i.e. max charges of Herco under 124gr bullets that will safely give you 1300 FPS from a 4" barrel, but wear out the throat in a short order. Many people don't understand that with increased velocity comes increased recoil and battering of the frame and slide. They don't change springs. While the maximum safe load may be alot higher than what they publish, that very same load will quickly beat your gun to death if you don't tame it with a comp or a heavier recoil spring.

This is consistent with my experiments.
More power can be squeezed out of pistols than book loads, sometimes two or three times as much power. But only a small percentage of increased power can be compensated by increased force recoil springs.

About half the energy goes into accelerating the hand, arm, and pistol frame.
The other half goes into accelerating the slide relative to the frame. This second energy must be absorbed by the recoil spring, or obnoxious slide slam will result. A 48 pound triple recoil spring assembly in a Glock 19 does not begin to compensate for the power potential of 9mm. And such a spring brings with it a host of other problems.