The Thompson, especially the early Model 1921, has a fairly high rate of fire at 900+ rounds per minute (rpm), higher than many other submachine guns of smaller caliber. This rate of fire, combined with a stock with excessive drop, increases the tendency of the weapon to climb off target in automatic fire; however, proper shooter technique can alleviate this somewhat. Compared to modern 9mm submachine guns, the .45 Thompson is quite heavy. By the standards of the day the Thompson was one of the most effective and reliable submachine guns available.