Lead vs Plated Bullets

Ganderite

Ganderite

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I just found something very surprising to me.

I was testing some ammo today as part of a load development. Trying to make full-power 38Spl ammo.

A Hard cast and lubed lead 158SWC and a Plated 158 SWC (Campro).

Lead bullet is .358" and the Campro is .357"

Same brass and primer with same powder charges.

lead bullet - 955 fps campro 765 fps

WTF???

You seen this before? I have used both types of bullets and can't say I have ever noticed a big difference in velocities.

The other thing that came out of this test was the difference in guns. I tested ammo in a Ruger 3" and a Smith 4"

Same ammo: 3" Ruger 982fps 4" Smith 955fps

I know different guns generate different velocities, but to get the higher velocity out of the shorter barrel was surprising.
 
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Lead would be slicker. I had known to pay attention to where load data specifies bare lead vs copper and not blindly using the other kind of bullet expecting the same (or as safe!) a result. Hadn't paid a lot of attention to how different they'd be at the same powder charge so thanks for doing the testing! And yes, I'm glad you're okay and nothing went wrong.

With the .38 Special vs .357 Magnum and .45 Colt vs .454 Casull my own rule was to stick with lead for the mild loads and copper for the super boomers just to provide an extra level of safety against accidentally getting ammo mixed up since they look different.
 
old303 said:
Lead would be slicker. I had known to pay attention to where load data specifies bare lead vs copper and not blindly using the other kind of bullet expecting the same (or as safe!) a result. Hadn't paid a lot of attention to how different they'd be at the same powder charge so thanks for doing the testing! And yes, I'm glad you're okay and nothing went wrong.

With the .38 Special vs .357 Magnum and .45 Colt vs .454 Casull my own rule was to stick with lead for the mild loads and copper for the super boomers just to provide an extra level of safety against accidentally getting ammo mixed up since they look different.
Click to expand...

I do a similar thing. The hot loads get the nickel plated cases,
 
interesting difference between 3" Ruger and 4" Smith, I expected it the other way around. Would a slight barrel diameter difference have caused this?
 
The light was dropping. No errors or missed shots, so I was not suspicious of the readings. I was using a ProChrono DLX. It has been reliable in the past.

I will re-test tomorrow in bright sun light. Same gun and ammo.
 
Ganderite said:
I just found something very surprising to me.

I was testing some ammo today as part of a load development. Trying to make full-power 38Spl ammo.

A Hard cast and lubed lead 158SWC and a Plated 158 SWC (Campro).

Lead bullet is .358" and the Campro is .357"

Same brass and primer with same powder charges.

lead bullet - 955 fps campro 765 fps

WTF???

You seen this before? I have used both types of bullets and can't say I have ever noticed a big difference in velocities.

The other thing that came out of this test was the difference in guns. I tested ammo in a Ruger 3" and a Smith 4"

Same ammo: 3" Ruger 982fps 4" Smith 955fps

I know different guns generate different velocities, but to get the higher velocity out of the shorter barrel was surprising.
Click to expand...

As others have stated, a lubed lead bullet has less friction than a jacketed bullet.
What i have noted is regarding loading data. For similar velocities, where manuals differentiate by bullet type and material, the powder charge is always reduced for lead.

Regarding barrel length; I did read somewhere that Rugers generally have tighter barrel to cylinder clearance; the smith may be allowing just a bit more pressure to bypass the barrel. Maybe check clearance with feeler gauges if you have a set, I only have a Ruger, so nothing to compare it to here at home.
 
Was the cast bullet a Plain-Base or Gas-Checked?

The assumptions here are that the lead is faster because it's "slippier", and that the plated bullet provided more resistance, hence was slower.

The other factor aside from coating was diameter - the Campro was smaller in diameter to start, and impeded much more from obturating than the cast bullet.

For bullets of the same weight, by far the greatest factor for MV is pressure, and I think it's safe to say that the lead bullet had more pressure behind it even with the same load of powder. Why? Because its "fit" in the bore was much better than the Campro in each case.

Two more things:

1. the amount of force required to engage a bullet into the rifling is very little more for a jacketed bullet than for cast, and plated bullets have very thin jackets; and
2. an extremely "slippery" bullet (even one with excellent "fit" so it effectively seals the barrel) would allow very little pressure to build behind it and hence would have a much slower MV than a bullet that offers enough resistance to build pressure.

As for the shorter barrel being faster - as already suggested, each barrel is different. We see fairly common reports of identical loads faster in some 20" rifle barrels than other 24" rifle barrels, for example.
 
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I repeated the tests in the bright sun. Results were within 10fps of the previous test. So it is not a chronograph issue.

The plated 158 Campros run 75 to 100 fps slower with the same powder charge. e.g. Lead 1130 fps Campro 1020 fps

I also tried a different revolver - another Smith. It shot about 50fps faster with all ammo, but showed the same lead v plated differential.
 
While the results are not surprising I will ask again. Are OAL of the bullets and loaded ammunition the same? I'm sure you know that small differences in internal capacity can affect pressure in significant ways. If the bullets aren't exactly the same length and seated to exactly the same depth it could explain at least some of the discrepancy, beyond the explanations already given.
 
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I haven't worked up any loads comparing 38/357 158gr lead vs plated bullets, but I did work up some 148gr HBWC Speer & Hornady (lead) vs Campro & Berry's (plated) loads for my S&W 52. I did notice that the plain lead was faster, even with these relatively light loads.

Screenshot 2023-02-02 173056.png
 

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Interesting. I am transitioning from Epoxy Coated Lead Cast to Campro Copper Plated Bulllets. And yes, the Copper Plated is slightly smaller in diameter. I will also have to check the OAL. If the OAL of the Copper Plated Bullet is smaller, then, this might explain the variance. Assuming they have same OAL, then diameter, though very minute might be the factor. Too many factors to consider. Casings also varies in sizes. At least the depth, this might also cause pressure variance. To eliminate these factors, use casings of same brand. Check the weight and length of each casing. Same primers. Take 10 Lead Cast and 10 Cu Plated bullets of identical sizes and weight. Load same powder weights, OAL and lightly crimp to same setting. Then shoot under same conditions.
 
B said:
While the results are not surprising I will ask again. Are OAL of the bullets and loaded ammunition the same? I'm sure you know that small differences in internal capacity can affect pressure in significant ways. If the bullets aren't exactly the same length and seated to exactly the same depth it could explain at least some of the discrepancy, beyond the explanations already given.
Click to expand...

Same OAL, but given the large empty space in a 38 Spl case, a small difference would probably not do much.
 
Thinking it might not be surface slickness of lead vs copper so much as softness and the amount of shove needed to obturate into the barrel's rifling.

Pressure spikes in the chamber while this is happening could be notably different.
 
The OAL was set to match the crimping groove on the lead SWC. The seating die was not adjusted when switched over to running the Campro bullets. They did not have a crimping groove. SOA OAl was same fror both.
 
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