Pretty common technique, ie covering a muzzle with electrical insulation tape.

Now my Mauser M03 in .404, comes with little orange plastic inserts for the muzzle.

Back to the .45/70 Blaster. I'm glad Daryl mentioned 540 gr hard cast flat meplat projectiles as being effective.

I remember one of the "internet's" key effective recipes for them was they had to be driven really slow, the slower they were pushed the better they perform.

Obviously that magical flat meplat performs, as it makes the "bubble" that magiucally increases a flat meplats effective killing calibre size. A spitzer or round nose of course does not make the magical meplat "bubble" and only drills through a calibre sized hole, but the flat meplat, two or three calibre wound channels. Magic!

But for the .45/70 it must also be driven very slowly. To even be more magical.

Now Daryl is right. A 540 gr Hard Cast projectile will work in the .45/70. Seen one test on a elephant's skull on a fresh kill in Matetsi in Zimbabwe. Not sure about the slower the better though, except too fast might be counter production in the lead bullet might shatter instead. Which is a different story to "being slower, increasing penetration".

Now if I had a .45/70 Blaster, I would load it instead with 400 to 450 gr Barmes X's or a similar bullet. The lesser projectile weight would allow better velocity. And the "Blaster" isn't hampoered by a ridiulous 19th Century tubular magazine where pointed projectiles cause chain reaction explosions ...