I scored 32 out of a possible 20 with just a two shot group. See below:
It was a "Duplex" Load, but not what you might have thought. I make up 43 Mauser to shoot in my Mauser 71/84's out of Starline 45/90. I have a pet load with 500gr bullets, and one day I got to thinking that since that long neck gripped the full length of the 500gr bullet, why would it not grip two 250gr bullets lined up end-to-end? Fact is it does:
Just a bit of fun. The two bullets take very different trajectories, ending up 2-4 inches apart at 50 yds. I imagine this is explained by the upset caused as the two bullets start to separate as they leave the bore, plus the effect of the front bullet's shock-wave, "contrails", shielding effect, etc. One of the two bullets actually hit where aimed on both shots, so it appears that at least one bullet goes where aimed, and I have to think it was the front bullet.
I could only do this because of the long (0.800") neck of the 43 Mauser. You might be able to pull this off in the 45/70 and 458 Win Mag as well, but only if the rear bullet is firmly gripped, and that depends on the taper in the case. I chose a powder that had the rear bullet sitting on top of the powder column, which further prevented it from falling into the cartidge, and the same would be advised for other cartridges.