The single-stack .45 1911-pattern pistol has long been a favorite with many shooters not only for its handling qualities but also for its perceived "stopping power". Compared to double-stack "high-capacity" 9mm's and .40's, its ammo capacity may seem lacking to some. Here we see a 1911-based forty-five and its tradtional 7 + 1 payload.
With an 8 + 1 capacity, the old "forty-five automatic" would indeed gain an extra round before the old war horse ran dry but at what cost?
In my experience, that tariff has been reliability...not with every single 8-shot magazine and not in every single pistol, but in general, I observed decreased reliability which usually manifested itself in the form of either the slide not locking back after the last shot was fired or stovepiping rather than feeding the last round, which could be embarrassing in a match or the kiss of death in "the dark place".
Over the years I've owned different 8-shot magazines that would work all of the time in a few of my pistols, but only some of the time in others regardless of the ammunition being used, but take the same ammo and load it into a 7-shot magazine and it ran fine in the gun that balked with the 8-round magazine. I preferred magazines more likely to run all of the time in all of my 1911's and for me those turned out to be the seven-rounders.
I believe that shortened followers combined with springs repeatedly compressed more than would be the case with seven rounds in the standard magazine are the culprits but this is only my opinion as I am not an engineer. This idea does however "fit" with what I've observed so many times over the years: Initially, my brand-spankin' new 8-shot magazine works fine but gradually begins to have problems. I did not see these issues when using practically any quality 7-shot magazines.
I have accumulated more than a few 8-round magazines but found myself leaving them behind because I didn't trust them; 7 reliable shots were preferable to 8 "maybe's" in my view.
Eventually I tried Virgil Tripp's "Super 7" magazine spring and follower. Whether going into a 7 or 8-shot magazine, capacity is 7 round in forty-five caliber. The polymer follower has a steel insert where it contacts the hold-open lever so premature wear to the follower is eliminated which usually stops failures of the slide to lock open after the last shot. I tried a couple of these upgrade kits and was most pleasently surprised. I then bought enough for all of my 8-shot 1911 magazines and have never regretted it. "Sometimes" magazines became reliable as homemade sin in all of my 1911's.
Should you be interested, both the upgrade kits as well as complete magazines can be found here:
(I am in no way associated with this company other than as a paying customer.)
Speaking only for myself, I'll stick with 7-shot magazines (either from the factory or resulting from using Mr. Tripp's parts) in my 45-caliber 1911 style automatics. They've just worked best for me over the long term.