Drew has connections in the gun world that I don’t have and has been invaluable in finding resources relevant to service pressure loads that are possibly in play with these two inch twelves. I’ve been in touch with him over the last few years in private correspondence. He also shoots with borderbill on occasion. While I have a couple of satisfactory recipes, they rely on plastic gas seals. I’ve had a three season saga of trying to develop all fiber wads for my 2” 12 ga. guns. Bill in AZ , Brent in IA and I have been sharing information in trying to perfect a technique for consistent, low pressure loads for our guns. I have yet to pressure test the loads, but have recently come up with a consistent velocity load according to my ProChrono Digital. My previous results were all over the speed range which initially caused me to blame my Chrono. I dispelled that notion by shooting factory loads which were as advertised. Another man gave me a tip that when he was professionally testing pressures and velocity in fiber loads, two nitro cards were better than one most likely due to a tipping of a single NC releasing gases unevenly. Stack height is important. The two nitro card technique is also emphasized in Lyman #39 (1953) which gave 5 scenarios of stack height and wad combinations. Of the 5 possibilities we only have room for the 2 NC and one 3/8" fiber wad which was next to the last in recommendation. My initial theory was that seating pressure wasn’t important with modern powders. However, seating pressure was more than just the compaction of powder. Modern plastic wads are cupped which allows gases to push against the sides, effectively sealing against hull, chamber, forcing cone and barrels minimizing the uneven escape of gases which affects velocity consistency. Seating pressure isn’t important in modern wads. Seventy years ago in Lyman #39, it discussed seating pressures with fiber wads of various powders including Red Dot (60 lbs. in one recipe) which is hardly obsolete. I’ll get back to seating pressure momentarily. I had success with consistent velocity using waxed cardboard cupped wads which I made with a hobby shop press which is depicted earlier in this thread.
However, the making of the wads and insertion into a hull can be tedious. Not so much a problem making a pocket full of shells for an armed walk in the quail and woodcock woods, but time consuming nonetheless. I had a Captain Obvious “Eureka” moment recently when I watched a YT video of hydraulic compression of common objects. Not only did the material compress downward, but also spread outwards. With 60 lbs. of pressure, a fiber wad in a cylinder (hull) not only compresses vertically, but pressure spreads the fiber wad to the sides, providing a tighter seal than just sitting there with crimping pressure alone. No doubt once the 60 lb. pressure is released, there is some spring back, but nowhere as near the spring back as with a tempered spring. There is remaining side pressure held in check with final crimping. I also experimented with coating .125” nitro cards in honey beeswax. I make thin puddles on a piece of aluminum foil in a skillet. Not as messy as dipping in a wax pot. With the combined waxed NC and 60 lbs. pressure, I was able to obtain consistent velocity for the first time. Without the waxed NC, but with 60 lbs. seating pressure, velocity wasn’t as consistent, but borderline usable for my purposes. It’s easy enough to wax the NC so I’ll continue to do so. The wax doesn’t provide protection against powder or lead fouling, but it seems to provide additional sealing. I decided to experiment with American Select as that’s what Brent and I have in abundance. American Select is used in a published low pressure load for vintage guns in longer shells. That was our starting point. Brent’s progress with lube was encouraging, but we both have concerns about potential powder contamination through grease migration. With black powder’s bulkier loads, not so much a problem, but with smaller nitro powder loads, there might be a potential problem. There are storage work “arounds” such as storing and carrying shells with crimp down, primer up. Once I develop a better ¾ oz. load’s consistency in velocity, I’ll send the 7/8 oz. load and 3/4 oz. load off for pressure testing. I saw no point in pressure testing before I attained consistent velocity. I shoot the rounds out of a modern firearm to avoid stress on the old doubles. I chrono my rounds at the manual’s recommended 5’ separation distance and pay attention to the recommendation to remove screens and avoid bright sunshine skies. I either shoot under cloudy conditions or in the shade of a building with an unobstructed view of the sky as recommended in the manual. Gil