Bullet Data & Reloading Manuals

[Whiterabbit]

Would you say this is because Jacketed is 'slicker' therefore requiring less ooomph behind it?

I really should reiterate that this data did not take pressure into consideration. The spread on pressure was tighter using max loads compared to starting, so I used that so any interpolation would yield much more predictable pressure.

But given that pressure wasn't taken into account, velocity (which I'm only assuming is closely related to barrel-bullet friction) surely must be all over the map.

[NotEnufGarage]

try ammoguide.com

[Bill Steele]

I have never heard the 10% reduction for lead over jacketed rule of thumb. I think it would be difficult to come up with such a rule of thumb that actually panned out to be correct as there are many different lead alloys and many different jacketed bullet constructions.

In general it has been my observation that a given amount of a powder when placed under a given weight of bullet, will produce a higher velocty with lead than jacketed. This seems to be most apparent when you have a good match between lead hardness and load. I have always assumed this was due to the bullet sealing the barrel better and as such a highwe pressure was achieved. I can't recall reading any definitive data that supports this theory, it just seemed to be the most plausible explanation for what I have seen.

If my assumption of better sealing and resultant higher pressures is correct, then maybe that is where the rule of thumb for a 10% reduction comes from as given the non-linear nature of pressure for a given amount of powder in an ever decreasing space, a 10% reduction in powder for a given published jacketed load would result in a greater than 10% reduction in pressure, thus providing a significant margin for error.

[tackdriver]

10% reduction from the same grain bullet in FMJ into an equilvalent weight grain lead came to me from Lee Reloading, Hornady and in a reloading book whose name I forgets. I see no reason to not to trust these sourcesI woujld think (hope) they know what they're talking about. Ok, it isn't a rule, just a recommendation... It has always worked for me. Course I could just be lucky...
You might want to drop Lee an email and see if they still say this is the case. If they now say different, let us know.

[Whiterabbit]

The big question is if that is the recommendation, then why does the recommended data say otherwise?

[noylj]

Back in the paleolithic era, loading data was quite rare and was to savored.
Most of the time, you were the ballistician to determine what worked in your gun.
If there was data for your bullet weight, but not for your powder, you would go with that company's faster powder.
In other words, if you have 95gn data for Bullseye, that would be where you would start for Unique or Herco. You would inspect primers and measure case expansion and note how far the ejected case went and compared these to factory ammo.
If you couldn't find any suitable data for your bullet weight, you would look for data for a heavier bullet of the same construction.
Your problem is that you are looking for data for a very small capacity round that has almost no safety factor. All of my data is for jacketed. In general, cast lead data will be lower than jacketed, with the max load being maybe half way between the starting and maximum load for a jacketed bullet. However, again, .380 Auto is NOT a cartridge to play around with.
You may find some lead data in the Lee manual and certainly in the Lyman manual (neither are at hand to see what they have).
You can also check some of the reloading data sites such as:

http://www.handloads.com/loaddata/default.asp?Caliber=380%20ACP&Weight=All&type=Handgun&Order=Powder&Source=

http://www.reloadammo.com/380auto.htm

A part of the data at this site is:
80 grain Barnes XPB (.355")
Competition 2.1 gr. 786
Competition 2.3 gr. 873 (MAX)
Power Pistol 3.9 gr. 869 (max)
ZIP 2.3 gr. 776
ZIP 2.6 gr. 862 (Max)
True Blue 3.2 gr. 790
True Blue 3.5 gr. 878 (Max)
Silhouette 3.4 gr. 856
Silhouette 3.8 gr. 951 (max)
Universal 3.1 gr. 898 (max)
----------------------------------------
90 grain Lead RN (.355")
Bullseye 2.4 gr. 747
Bullseye 3.0 gr. 918 (max)
Titegroup 2.4 gr. 752
Titegroup 2.7 gr. 866 (Max)
HP38/W231 2.3 gr. 704
HP38/W231 3.5 gr. 997 (MAX)
Unique 3.1 gr. 759
Unique 3.5 gr. 810
Unique 3.7 gr. 922 (MAX)
Universal 3.7 gr. 964 (MAX)
Power Pistol 3.8 gr. 906
Power Pistol 4.3 gr. 965 (MAX)
----------------------------------------
90 grain JHP (Jacketed Hollow Point)
No. 2 3.7 gr. 930 FPS
No. 5 4.8 gr. 920
No. 5 5.0 gr. 1,062 MAX.
No. 7 6.5 gr. 970
Bullseye 3.0 gr. 940
Bullseye 3.3 gr. 998 (Hornady HP-XTP)(MAX)
Unique 4.0 gr. 940
Unique 4.6 gr. 1,034 (MAX) Speer GDHP bullet
HP38/W231 2.9 gr. 838
HP38/W231 3.5 gr. 957 (MAX)
Universal 3.6 gr. 955
VV N320 3.2 gr. 965
WSL 3.4 gr. 880
Ramshot ZIP 2.7 gr. 800 start
Ramshot ZIP 3.4 gr. 980 (max)
Silhouette 4.6 gr. 958 (near max)
Power Pistol 4.6 gr. 994 (max)
True Blue 3.7 gr. 800
True Blue 4.5 gr. 960 (max)
Titegroup 2.2 gr. 845
Titegroup 2.6 gr. 957
Titegroup 3.0 gr. 1,012 (MAX)
Titegroup +P 3.1 gr. 1,046 (+P MAX)
Unique 4.2 gr. 973
Universal 4.0 gr. 995
----------------------------------------
95 grain Lead RN
ZIP 3.0 gr. 845 Hi=867, Lo=817, ES=46
ZIP 3.2 gr. 891 Hi=903, Lo=883, ES=21.4
ZIP 3.4 gr. 957 Hi=971, Lo=950, ES=21 Very good loads
----------------------------------------
95 grain JHP (Jacketed Hollow Point)
No. 2 3.7 gr. 934 FPS (MAX)
No. 5 4.8 gr. 891
Bullseye 3.2 gr. 900 (FMC bullet)
Unique 3.6 gr. 762
Unique 4.2 gr. 910 (FMC bullet)
231/HP38 3.2 gr. 964 (speer FMJ)
231/HP-38 3.2 gr. 884
Tightgroup 2.9 gr. 776
Universal 3.5 gr. 901
VV N320 3.2 gr. 940
WSL 3.3 gr. 895
Silhouette 4.5 gr. 948 (near max)
Factory Browning 9mm short 845 fps. Hi=887, Lo=781, ES=106 (FMJ bullet)
Factory PRVI FMJ 776 Hi=806, Lo=754, ES=53
----------------------------------------
100 grain Hornady FMJ (Full metal jacket)
No. 2 3.4 gr. 793 FPS
No. 5 4.9 gr. 895
Bullseye 2.5 gr. 756
Bullseye 3.3 gr. 985 (MAX)
Unique 4.0 gr. 950
HP38/W231 2.5 gr. 712
HP38/W231 3.1 gr. 843 (MAX)
Universal 3.4 gr. 889
VV N320 3.0 gr. 885
Silhouette 4.3 gr. 935
231 3.4 gr. 870
IMR 700X 3.0 gr. 995
Titegroup 2.3 gr. 708
Titegroup 2.8 gr. 864 (max)
----------------------------------------
100 grain LEAD RN
No. 2 3.6 gr. 943 FPS
No. 5 4.5 gr. 922


Your best bet, besides those two manuals (and, maybe, Lyman's #3 or #4 Cast Bullet manual) is to call or email the various powder companies. If they have specific data, they will share it.

[Whiterabbit]

After perusing a few cartridges on the Hodgedon website, I'd say it's split 45/45/10. half the time, more powder is recommended when switching to an equal weight cast bullet. Half the time, less powder is recommended. 10% of the time, it's basically equal (44 mag especially)

I'm not sure that's statistically good enough to call a general rule.

Doesn't follow any patterns, either. Small bore, large pore, high pressure, low pressure, rifle, pistol, it's kind of a mix.

This is, of course, using only one data source (the Hodgdon website)

[tackdriver]

Enough to drive you crazy isnt it? Especially when one book calls for a max of 7g of a powder and another calls for a max of 12g of the same powder for the same bullet.
It's a wonder people arent blowing themselves up right and left!