I was looking through my spreadsheet of handload data and noticed something interesting - there is a difference between the velocities of equal bullet weight/profile for bare lead and Hi-Tek coated. This is true for the same primer, powder charge and gun used. My example data from .38 Special:
COAL__________Bullseye Powder____100-gr Lead RNFP bullet________________________Barrel
1.402-1.409_____3.4________________802_____________________41.2____REM 1.5 SPP____5.5
1.402-1.409_____3.4________________1016____________________79.2____REM 1.5 SPP____20
COAL__________Bullseye Powder____100-gr Coated RNFP bullet_____________________Barrel
1.440-1.455_____3.4________________610_____________________79.5____REM 1.5 SPP____5.5
1.440-1.455_____3.4________________934_____________________147.3___REM 1.5 SPP____20
These were shot during the SAME RANGE SESSION so you can't go looking for different meteorological factors as having an influence. The only other variable betwixt these two loads was COAL - the bare lead ones were from a batch I ran trying to get an extra round into the lever gun's tubular magazine while the coated ones I just seated to the cannelure. For .38 Special it really shouldn't matter, especially with a powder like Bullseye.
What surprises me about this is that EVERYBODY says, "Just use lead data for loading coated bullets," when it is demonstrable that they do NOT give the same velocities. In fact, they give markedly lower velocities. To drop from 802 fps with bare lead to 610 fps with coated is rather significant. Even the rifle length (20") barrel shows some decrease (1016 vs 934). The ES also got larger with the coated bullets (yet another factor for that thread running around regarding what all influences ES) which doesn't really help matters.
Now the attraction to coated bullets isn't all about raw speed. Usually, it's people who want to minimize interaction with bare lead without having to go to the expense of jacketed/plated bullets. For Cowboy Action Shooters it is the only sanctioned route to avoid bare lead slugs. Then there are people who just like the pretty colors.
I also ran this with Red Dot and bare lead slugs versus Promo and coated - all using same primer and powder weight charge in the same guns. The 100-gr bare lead (with 3.4-gr red dot) gave 798 fps in a 5.5" barrel while the 100-gr coated (with 3.4-gr Promo) gave 659.1 fps in the same gun.
Rifle data (20" barrel) showed similar at 1005 fps for bare versus 928 fps for coated. So this isn't just one data point.
The good folks at SNS
have information about these bullets for those curious.
I did find a source
that admits these bullets run slower
than bare lead but they didn't agree with me by how much:
Load data – We recommend that you use published lead load data from reputable sources. A coated bullet will run slightly slower than a lead bullet (5FPS-10FPS.)
This is usually only going to matter to a shooter that is loading to a Power Factor for competition. If you have any questions don’t hesitate to send us an email at email@example.com
. Hodgon's website is a good place to start if you need some help with load data.
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