the jim513350 is very simular to the rapine 350T bullet so it will work very well through spencers and keep pouder fouling soft ,i also lick the look of there jim513375 bullet ,it should cary enough lube for the carbine,if same desine had a big lube groov i think it would be near perfect bullet for original spencers and would give beter acuracy AS carbines,i think you should order a few of each jim513350 &jim513375 bullet and try before buying a mould ,good luck