The problem with all the gates on powder flasks and horns is that residue builds up on the gate. Humidity condenses on the brass or steel metal, and the black powder dust sticks to it. When it dries out, the dust is flammable. The gate's purpose is twofold: One: to cut off a measured charge for your gun: two: to act as a physical barrier in the event any fire or spark gets to the powder charge in the tube, to prevent it from igniting the larger powder charge in the flask or horn, creating a bomb!
Now, if the gate is coated with black powder residue, and if its flammable, the concern is that it cannot reliably perform its second, and major safety, function. That residue, in my personal experiences also prevents the gate from closing off the powder charge, making the first function questionable. It was this occurrence which had me take the measure apart, and that is when I found all the black powder residue on the gate and surrounding structures.
If you clean that gate frequently- like after every trip outdoors in humid conditions, or in cold conditions when you go from the cold to a warm indoors where condensation hits everything, including the lens of your eye glasses( a good clue that you need to attend to your flask and gun) then I think the metal gates will perform both functions correctly, and there is little danger of an explosion or fire. At the very least, the gate should be cleaned everytime you fill the horn or flask with powder. Keep both moisture and oil off the gate, as both attract powder residue.
However, to be on the very safest side of this, load from the flask to a separate powder measure- as required at all NMLRA sanctioned shoots- and then to your gun. YOu can expect any range officer who catches you loading from the horn, even with this kind of gated measure attached to the horn or flask to order you to stop doing it , or leave the range. His job has to be to worry about the safety of all shooters, and worry about the liability of the range owners if you or someone should be hurt. Don't give him any backtalk. It is because of him, and the enforcement of sterner rules that we have gun clubs with ranges, and these clubs can obtain any kind of insurance coverage. Without insurance, no one could sponsor a shoot.
If you had to pay a $100-$500 entry fee just to shoot a monthly match, most of us would not be shooting at our clubs, or even be able to join as members. The reason we can shoot so cheaply is because the long and excellent safety record of shooting ranges, with their tough range rules, and tougher range officrs, has made our sport very safe, and the number of incidents that occur each year very small. Considering the catastrophic injuries that can occur should a spark get into a flask or powder horn, it does not take a genius to understand that even one such event would raise insurance premiums to a level where most clubs could not afford them.
Have a good time, but always, first and last, be safe, for your own sake, for your family's sake, and for the sake of your friends who shoot with you. We have enough Accidental discharges, mechanical failues in equipment, and other problems on ranges when people allow themselves to be distracted, or just don't know what they are doing, that we don't need to increase the risks out there.
