IIRC in the old days, in movies movie prop makers had issues with getting the 45 acp blank ammo to feed and reliably cycle the guns. I believed, for a long time that it had to do with the low pressure of the 45 acp. But according to this article that was not the case.
Why Did Hollywood Shun the Colt .45 Government Model in Cinema? - Guns & Ammo
"According to Mike Gibbons, former owner of Gibbons, Limited, once one of the largest current suppliers of firearms to the motion picture industry, a 1911 was no harder to modify than was a 9mm or other caliber. The reason they were not used widely in early films actually was because of the blanks themselves. Until the last few years there was no brass available that would allow a .45 blank to be made with a full crimp—a feature that was critical for proper feeding. One alternative involved using standard .45 ACP brass with card wads, but there were chambering problems, and wads have a tendency to gum up the works of an auto. Some loaders even tried to trim down .30-06 brass, but the cases were just too thick to effect a good crimp.
Back in the old days, there were three major Hollywood firearms suppliers, Stembridge Gun Rentals , Ellis Mercantile and The Hand Prop Room. All had their own particular style of blank, and very often an Ellis blank would not work in a Stembridge gun, or vice-versa—magnifying an already difficult situation.
Read more: http://www.gunsandammo.com/blogs/history-books/why-did-hollywood-shun-the-colt-45-government-model-in-cinema/#ixzz5NPtelJfw"
The death of Brandon Lee changed some particulars of how blank guns are used. A different type of restricter barrel was developed.
Explanations of how they work are in the links below and of the "ammo" used in them.
.45 ACP Brass Blank Ammunition
Modifications to a pistol to allow blank firing?