Brass Shell Loading:
 

Finished up the 16 gauge, time to load the 12 gauge. The vintage Rem/UMC and Winchester shells were cleansed in a tumbler containing water, Dawn dish soap, a pinch of Lemi Shine and a pound of stainless steel pins. In 4 hours they came out like new. I sealed the over shot cards with Sodium Silicate, works great covering the entire card. The vintage shells loaded without incident, however the Magtech hulls were a different story. The primer pockets were too small and required reaming and swaging. The flash holes were also too small and needed to be sized larger to allow for primer removal with a sizing die decapper pin. Once those two hurdles were cleared it was smooth going.
Using the published Parker Brothers data this is my mild 12 Gauge Load:
2-3/4 Drams FFG Black Powder
1 oz. #8 Shot
Update: 85 12 Gauge are completed today. I'm going out early Sunday morning and shoot some clay pigeons with the Parker Bros 16 GH and the Clabrough 12 gauge. The Parker 16 DHE with the ventilated rib won't be making the trip, I have not as of yet had the cracked forearm repaired.

Brass Photos:
 

Finisher the 12 Gauge, found another 50 16 Gauge to load. The original brass 16 gauge are seriously hard to find. Of all my brass only two are Parker Bros head stamped. I have a source for vintage Rem/UMC and Winchester brass, I didn't mention the affordability factor. They are pricy, like most anything these days.

Something I am curious about, the overshot cards appear to be paper. I was thinking for waterfowling or in non ideal conditions some sort of waterproof paper could be used.

I cover the paper overshot card with Sodium Silicate, the shells are impervious to moisture.

Lucky day. I checked out a pawn shop and was scrounging through some unmarked plastic boxes and sourced two large primer pocket reamers, one does width and one for depth (adjustable). Also found a flash hole reamer. These vintage tools make the task much easier. The Magtech brass flash holes were too small to use the decapper pin, so the flash hole reamer makes the holes uniform and just the right size. So for the $15 investment I ramped up production, about 140 12 and 16 gauge are completed, though there are about 50 more to finish.
The vintage UMC/Remington, Winchester and Parker Bros. brass shells only require cleaning, they are much better quality than the Magtech. Interestingly the Parker "12A" brass measure 2-5/8" and all the other brands measure 2-1/2".

They sure look great but it is a labor of love. You can see why the old time market hunters were up all night loading brass shells.

So how did they shoot?

I used a deprimer punch and bushing on a Mec 9000H. I had to hand load the primer and stopped at the crimp station. I ended up selling 200 Magtecks and the reloding set up to a cowboy shooter.

"So how did they shoot?"
Going to pattern and bust some clays tomorrow. This old thrower is older than dirt but works well.

Great set up Bruce! I do much the same only for 12's I use 3 drams of OE 1.5 powder as I have found it to be the cleanest and softest fouling powder to load. Also use a lubed fiber wad to keep the flying bits from my face when the wind is blowing towards me. Great fun using the all brass hulls. I have mostly REM/UMC with a good number of Winchester. Are the two brass cylinders in front of the funnel brass re-sizers? Work well for sizing if you fire shells in more than 1 gun. I found mine at a gun show many years ago in an box of reloading stuff. I suppose a i-net search could locate one for sale. Many do not know what they are or what they are used for. Necessary item for me.