It's been a long time since I was in tube artillery, but I do not recognize this model. The carriage sort of looks like a hybrid 155 M1 (Long Tom) carriage, but it's missing the second set of wheels. The howitzer mount, elevating mechanism, equilibrator, recuperator, recoil cylinders, and muzzle brake are of unknown design. But, having said that, I'll be the first to admit that it's not fair to compare this to a scale model. It's an approximation and it makes a great flat car load.
Which reminds me … didn't Life Like produce M1A1 105mm howitzers in 1:40 or 1:44 scale back in the day?