Multiaccess communications over a slot-synchronized collision channel without feedback is studied. Collision immunity is gained by employment of short codes, followed by periodic non-ideal interleaving. The authors examine the achievable rate region and throughput in terms of both the capacity and the short-coding error parameter (SCEP), In case the channel utilization factor does not exceed 1, the throughputs are shown to be lower bounded by positive numbers, which are also the limit values for infinitely many users. The optimal value of the channel utilization factor is found to be less than 1. The throughput of a network that employs a family of RS codes of fixed length is found to be in accordance with the SCEP-based throughput.