Ready to PC, few ?

[talonxracer]

powder coat before the gas checks, personally I wouldn't even use the gas checks they really are superfluous with the powder coating.

[boost]

Thoughts from someone who is trying to learn.

Gas Checks -
I don't like the added expense. I worry about a gas check dangling about inside the case unsupported except by propellant. Aluminum is not an abrasive, aluminum oxide is a good one and contact with air (oxygen) starts raw aluminum building a coating of oxide. Gas check add a 'more' flat base to the bullet, allowing a better/quicker obulation (never could spell that word, or say for that matter). The gas check 'step' inhibits a good seal, thus a gas checked or flat based bullet will both shoot better and lead less.

Proper size bullets -
(Don't jump me for the extreme numbers I'm using, they are only examples)
The bore is .308, the desired bullet diameter is .310, the coating is .0015 (two sides - .003 total), as cast bullet is .312. Coat the as cast bullet for .315, size to .310 and loose/disrupt the coating. Or, size the as cast bullet to .307, coat to .310. Or, size the as cast bullet to .308, coat to .311 and size to .310. As long as the desired size is found and the coating is intact, it is only the process to get there.

Coating the base -
The PC protects the sides of the bullet in the rifling, minimizing lead contact. This is good
The PC can protect the base from pressurized hot gas. To what extent, I don't know. For low/er pressure bullets (9MM - your example) raw lead doesn't lead the bore at normal velocities/pressures. At what pressure/heat point will PC bases stop being protected? Looks like testing time.

I don't think I answered any question but maybe I clarified (or muddled) some.

Load with care and enjoy,

OSOK

well you answered my question about aluminum. When I saw the word "aluminum" ,sand paper, grinding wheel, & cut off wheels came to my mind. if it works well I have no problem of using aluminum gas checks.

[oldpapps]

Aluminum can are coated/painted/whatever to keep them from oxidizing. The only raw part would be where you shear the metal. I don't have/use a can gas check maker but would think that the raw edge would be shoved into the first drive band and have very limited contact with the barrel if any. I wouldn't have any concerns with using them. Graphite is an abrasive if there is absolutely no moisture. Think free space, in orbit maybe. I don't think I'll get up tight over that either.

Enjoy,

OSOK

[caliplt]

For as much 300 BO/7.62 x39/.308 as I shoot...it just makes sense to buy a forming die and make my own from aluminum cans.

[boost]

stop EdUmAcAtiNG me, you guys are costing me money

[caliplt]

While waiting on my die, I've cut the tops and bottoms off of all my aluminum cans in preparation! I should have enough for at least 10,000 checks. Thus, adding gas checks for better accuracy is nothing to me! You can also sell them on Ebay and the forums to recoup some cash.