Increase in Velocity - PC

[straight-shooter]

I shot a bunch of new loads using Hodgdon CFE Pistol powder yesterday. I compared notes with another reloader who shot the same bullets only his were lead and mine are lead with powder coat. We're both using the same length barrel semi-auto. I'm seeing a 80 fps increase with the powder coated bullets.

Whatcha say Firing Line ?

Does PC increase velocity ?

Now this begs the questions that even with the increased velocity, would the pressures be the same of the slower lead load ?

 

[Unclenick]

Did you both use the same brand of primer? Are the bullets the same length and seated to the same depth? Do your barrels slug the same? Do you have the same headspace in both guns?

Really, the only way to prove this one way or the other is to be sure you have the exact same components, except for the powder coating, all loaded on the same press setup, charged with the same powder dispenser, then go to the range. With both guns clean, shoot just powder coat, clean them again, then shoot just lead. See if the velocity difference shows up in both.

In theory, though, what you describe is possible. The coating could fatten the bullets enough to make a tighter and less slippery fit, and that will, indeed, raise velocity by increasing start pressure (which raises peak pressure, too, by the way, so keep an eye out for pressure signs). Moly coated jacketed bullets always shoot about 50 fps slower for this reason; more slippery.

My goodness, isn't it strange to see how many cast bullet shooters are getting PC these days?

 

[Hunter Customs]

If the loads are the same except for the powder coating, shoot them both through the same gun, that should tell you if there's a difference.

 

[Beagle333]

My powdercoated ones are a bit slower. Current thinking is because they are more slippery and therefore don't allow as much pressure to build up behind them. Not a lot slower..... somewhere around 10-15 fps for the big .45 slugs moving 850±fps, and 35-40 fps slower for .357's going 1100± fps, at least according to my Shooting Chrony.

 

[A pause for the COZ]

My test have shown the opposite.
Same exact loads, same exact gun, same day. Same bullets.

The powder coated loads all ran slower than the standard lubed loads.

I can infer from that. The Powder coated bullets are slicker and easier to push than standard cast/ lubed bullets.

So I am with Beagle on this

 

[Unclenick]

Seems like that's what should happen, but he may be seeing tightening. Also, there are a number of different plastic powders out there. The polyolefins, like PE, are going to lubricate well. I'm not so sure about epoxies, though.

 

[Beagle333]

I did not take tightening into account on my testing. I resized mine after coating. The way I powdercoat, it adds about .002" to the bullet. If you were to leave it that way, I guess it would stuff into the bore a bit tighter than a regular bullet, but again I have not tested this.