1.285 should be ok, but the problem may arise if the ogive of the bullet runs into the rifling. Try a dummy round with the bullet seated but uncrimped. If it is too long, the bullet will be pushed back into the case.
Three solutions,
take the base pin latch apart and stretch the spring a little bit
take the base pin out and deepen the groove
buy a Belt Mountain locking base pin
I would reccommend the last one.