Powder coated bullets is only the coating going into the rifling?

[Nomad666]

Powder coated bullets is only the coating going into the rifling or is some of the cast lead also going into the rifling as well what about only one coat of PC or two coats of PC make a difference then too?

[Tenbender]

No. Shoot one and dig it out and look. The groves are there from the rifleing and the PC is still in the groove. The only way the lead won't contact the rifleing is if the boolit is way undersize. And I mean way undersize. When the powder charge ignites the boolit will compress making it larger when it inters the bore.

[Grmps]

↑↑↑ that ↑↑↑

powder coating is used basically as a lubricant, it forms a thin polymer /polyester film between the boolit and the rifling. powder coating also works as a boolit enlarger adding .001 to .004 to the diameter of boolits (depending on the powder and number of coats).

It is not recommended to and to many coats since this could throw off the balance of the boolit

[rsrocket1]

It also acts as a protective layer from gas cutting at the early stage of ignition. The PC gets gas cut rather than the bare lead. Any residue in the grooves is easily removed with a piece of paper towel dampened with #9, CLP or your favorite cleaner. It also comes out with a run of a bore snake.

[Nomad666]

OK thanks for the info.

I was wondering if it then mattered if the bullets were water hardened or not now it sounds like I should be water hardening boolits and also powder coating under 250F the elvis method to keep em hard.

Yes I noticed the bore had a light dusting that settled to the bottom of the barrel and did clean up with just a patch that I ran threw after a dozen or so rounds but do think my very poor groupings were from to soft a boolit.

Always learning more as I go along.

[Dragonheart]

The Polymer forms a jacket that actually bonds to the substrate rather than just encasing it like a metal jacket. Typical rifling is approximately .004" from land to groove and according to our PhD Polymer Physicist the depth of the PC should be 2-3 mill from the substrate to perform properly on higher velocity loads.

Due to the hardness (typically in excess of 20 BHN), toughness and elasticity of the polymer, it provides lubricant, seals and resists the torque of spin-up. PC performs like a jacket so much softer alloys can be used. I personally have fired PC cast pure lead in excess of 1200 fps with no leading. According to the pressure tables that would be impossible with any standard bullet lubricant.

Due to the superior lubricating properties of the polymer the barrel runs cooler with an increase in velocity, not my words, the has been proven by Federal in their testing. When fired the polymer conforms with the alloy substrate into the rifling and remains intact throughout the bullet's flight, until impact.

For the polymer to be effective it should not have bare spots that can touch the barrel and it needs to be properly cured.

[brewer12345]

So given all of this, do you size as normal when you pc? If I normally size to 358 with conventional lube do I do the same after I pc?

[ThomR]

OK thanks for the info.

I was wondering if it then mattered if the bullets were water hardened or not now it sounds like I should be water hardening boolits and also powder coating under 250F the elvis method to keep em hard.

Yes I noticed the bore had a light dusting that settled to the bottom of the barrel and did clean up with just a patch that I ran threw after a dozen or so rounds but do think my very poor groupings were from to soft a boolit.

Always learning more as I go along.

Some powders won't work well with the low temp bake method, some do. You will have to do the cube test to find out for sure if your powder coat will work or not.

[Dragonheart]

I size based on my barrel groove, but .001 over is not a problem and some say they get better accuracy. Problem with the smash test is it only partially evidences the bond and elasticity of the polymer and not the hardness and durability of a completely cured cross linked polymer. Those that rely on an partial cure just to save a little time are not getting the full benefits of the polymer.