Habt ihr euch bei Gelegenheit noch mal die Diskussion von 2021 dazu angeschaut? Marlin 1894 Carbine .44 Mag. mit Microgroove-Lauf
Ich hatte dort auch einen Beitrag geschrieben, das in dem Marlin Forum mehrfach beschrieben wurde, daß unbedingt Mantelgeschosse oder auf .432 kalibrierte Bleigeschosse gebraucht werden.
Das wird auch hier gut beschrieben:
There has been a great deal of concern over the years about whether or not Microgroove rifling would shoot cast bullets well. One group of folks says that Microgroove rifles can't hit a barn from the inside with cast bullets, one group says that Microgroove barrels shoot cast just fine just so long as velocities are kept below 1600 fps, and one groups says that Microgroove barrels shoot cast just fine at full throttle. The key to success with cast bullets in a Marlin with Microgroove rifling is to keep in mind that these barrels tend to have oversized groove diameters, and that the grooves/lands are shallow. Therefore, in order to get proper engraving (and minimize "slippage" of the cast bullet as it enters the shallow rifling), it is necessary that the bullet completely fill up the groove diameter of the barrel, and engage the maximum amount of the driving surface of the lands. Since Microgroove barrels are commonly oversized, this means that the cast bullet must also be oversized to effectively "fill up" the grooves. Other factors that also contribute to good accuracy with cast bullet in Microgroove barrels are the use of a GC bullet (which helps to provide a better grip and seal), and making sure that bullet are cast hard enough for the application (generally a BHN of 12 or more). It is also worth remembering that throats in modern rifles are almost always cut larger than groove diameter of the barrel (to insure that ammunition can chamber easily), and that best cast bullet accuracy is obtained by fitting the bullet to the throat, hence reinforcing the need for oversized cast bullets in Microgroove barrels (for example, the throats on my .30-30s run almost .311", so I size cast bullets to .310" for these guns).
Daher würde ich mir Experimente mit auf .429/430 kalibrieren Geschossen (auch sehr harten) sparen. Was aber funktionieren könnte, wären leichte Ladungen mit offensiven Pulvern und eher weichem Blei --> Geschoss wird gestaucht. Würde ich persönlich aber lieber lassen.