I'm 95% sure the No. 25 shot tube's end cap is a zinc alloy, it's definitely too heavy to be aluminum.
I decided to shorten a 25 shot tube so I could use it without a spacer in a model 96 I have. It's a nice shooting gun in very decent condition. I replaced the trigger with one from a model 99, and Shane refinished a Daisy 99 stock that I put on it. The gravity feed shot tube works well enough, but I just like the 25 tube more, so...
The process of shortening the shot tube went easily enough, it entails taking about 0.200" off the muzzle end of the inner BB tube and the outer shot tube 'cover' and taking a bit off the BB follower so it clears the fill hole when fully retracted. I should have taken a smidgen off of the spring, too, but I thought the spring could absorb the difference in length. But I found the spring wants to bulge out of the fill hole when the follower is pushed forward to lock it for filling the magazine- so I should have taken the same amount off of the spring as I did everything else. I used a bench grinder since the amount to remove wasn't very much, but a hacksaw or dremel could work, too. I cleaned the ends up with a dremel and recrowned the shot tube using a cratex point in the dremel.
NOTE- The amount to remove from the shot tube can vary from gun to gun, so measure for the gun that the tube is going in before proceeding. On all the gravity feed guns I have around here, taking off 1/4" would make a shot tube that would fit them all. I hate giving away ANY length of the shot tube, but the 25 tube is already 1/4" longer than most gravity feed tubes, plus it's more efficient, so it's still a better option in my opinion.
The only touchy part was drilling the hole through the outer cover for the roll pin. The edge of the hole is 0.038" from the end of the cover. On this one, I installed the end cap and used a spring-loaded center punch through the holes in the cap to mark the outer cover for drilling. Once the holes were in the outer cover, all that was left was to reassemble it, and that is straightforward and was uneventful.
Unfortunately, when I installed the shortened 25 tube into the 96, the shot tube cap is causing the shroud to spread at the seam when it's tightened down. I should have test fit the cap into the end of the shroud when the shot tube was apart, so it's on me. I am considering my options for removing some material from the cap OD, but I've not decided on a method yet. Any ideas come to mind?