:) Hello Nelson, it just so happens I own one of these rifles. Bought it when they first came out.
Serial # 5797 made 3696 rifles before yours. It's in excellent condiction, fired with Remington
factory loads about 20 times. A box of ammo was given to me by the shop when I bought the rifle.
Never fired reloads through it, but if that day ever comes I will use a powder disigned for reduced loads that
is not position sencitive, produced by Accurate Smokeless Powder Co. A low pressure load for the
Springfield Trapdoor would be using a 405 gr. lead bullet 24.5 to 27.5 grains. The Trapdoor action is not
a very strong action Nelson. Can't use just any 45/70 ammo in it, the box must be labeled 45/70 Govt.
Standard Commercial Ammo only.
If it ain't don't buy it or use it. My rifle shot very well. It's been so long since I shot it, but when I did, if my memory serves me right, it shot good groups at 100 yds. Good enough to kill deer out to 200 yds.
Be advised only 10,000 H&R Officer's model's were made as there Centennial model and there is some collector value. I've seen at gunshows a few in only good condition priced at 12 to 16 hundred dollors.
BTW, the barrel has a 1 in 20 twist rate. I hope this helps you a little.