Confirmed Fitment
Rock Island MS Magazine Loader
The Rock Island MS is confirmed to fit the Super Thumb ST1, the loader ADCO builds for standard double-stack service-pistol magazines. It loads Rock Island MS magazines faster and with far less thumb strain — a purpose-built tool, not a one-size-fits-all compromise.
Why loading these magazines is a fight
Double-stack magazines get progressively harder to load as the spring compresses — the top few rounds are where thumbs give out. The Super Thumb pushes each round straight down against that spring tension for you, so topping off to full capacity takes seconds instead of sore thumbs.
Your Fit
Super Thumb ST1
Double-Stack
Width
1.29" (32.5 mm)
Height
0.86" (21.9 mm)
Rock Island MS loader — common questions
Which Super Thumb fits the Rock Island MS?
The Rock Island MS is a confirmed fit for the Super Thumb ST1. It appears on ADCO’s verified Super Thumb fit chart as an exact match.
What kind of magazine does the MS use?
The Super Thumb ST1 is built for standard double-stack service-pistol magazines, which is the class the Rock Island MS uses.
Will the same loader work for my other Rock Island pistols?
Often, yes — many Rock Island models share the same magazine class. Check the other Rock Island fits listed below, or use the Model Finder to confirm your exact model before ordering.
Is the Rock Island MS fit guaranteed?
Every Super Thumb is backed by a lifetime warranty. If you’re not certain, confirm with the Model Finder or call ADCO at 781-935-1799 before you order.
Not 100% sure? Confirm before you order.
Super Thumb loaders are model-specific. Use the Model Finder to double-check your exact firearm and magazine, or call ADCO Arms and we'll confirm the right loader for your Rock Island MS. Every Super Thumb is backed by a lifetime warranty.