Powder Coat and Sizing

So I've been reloading for a year or so now, and I've shot plenty of cast boolits, but up to this point I've purchased all of my boolits online rather than casting them myself as I didn't previously have a cheap source of lead. That has since changed and I'd like to try my hand at powder coating. I've been told before that powder coating has a small amount of rebound; for example, if it has been sized to .356", it will end up at .357" diameter. I would firstly like to know if there is any truth to that claim. Secondly, I've been told that black powder coat has abrasives in it and is not good for your gun, yet I've seen plenty of pictures of black PC bullets. Is there any truth to that claim? Thirdly, I would like to start casting for my 30-06 and have been told before that it is better to use boolits that are oversized by .002-.003" rather than the typical .001" for faster rifle calibers; basically I want to know whether I should get a .309", .310", or .311" sizer as i don't really have the money to throw around to get multiple sizers to see what works best. I did slug the bore and it is .3075"

Th abrasive powder is harbor freight flat black. I cannot verify this but it what I've heard.
I have sized many PC'ed boolits and have yet to see any noticeable "rebound"

Don't think my PC coated Bullets rebound when sized as such its dependent on the alloy I believe, for example my lee .358 sizer will size soft lead 40-1 alloy at .3575 and 14.3 Brinnel WW at .3585

Cheers

3rd question, answer...you can't generalize what size to use based on caliber. If you do, start with .001 over normal jacketed bullet size, so .309 would be a place to start.
What you will find is that you need to go by each barrel individually. Buy some cerro-safe to check throat sizes and size bullets to the throat.
You can have two identical Rem 700 30-06, and one may shoot .309 and the other may like .310
Dan

NJWoT welcome to Cast boolits. Sizing to .309 is standard for most modern 30 cal rifles .0015 over the bore diameter is good IF they chamber in your gun.
Different firearms like larger or smaller boolits which also depends on how hard the alloy is -- softer alloy you tend to want to cast larger boolits.

PC (powder coating) is/forms a polymer coating usually .001 to .002 thick any "spring back" would be in the lead and most likely won't be noticeable. NOW if you cast with a hot alloy you boolits will drop from the mold smaller than if you cast in the 680-700° range.

I would suggest first slug all your barrels before buying anything and size based on the groove measurements taken from the slugs. I slug by firing a PC lead bullet into a water trap at a very low velocity. A Cerrocast of the chamber will give you the throat dimensions if you want to check or fit the bullet to the lands. I double PC my rifle bullets (appx. .003") as I want a thicker jacket for full power loads. I size .0015" over groove.

When you size PC the polymer is harder than the alloy so it is the metal that is moved. I have never noticed any spring back in polymer that is a characteristic of metal.

I would suggest going with a know powder when first starting out, like Smokes. There are too many powders and additives out there, so you would have to zero in on a powder to find out what is in it, but I know of none that contain abrasives.

1,2 and even 3 thou's over size is a general rule of thumb
you need to see what you gun likes buy all the sizes you want
to try and find the one your gun likes
cast,powder coat then size and check if you have to
once you boolits are sized you are good to go
but it's always advisable to re-check before you load