Daylight Gun

The M1909 Benét-Mercié was known as a "daylight gun" because the feed strip needs to be "just-so" to be successfully inserted into the feedway.

GURPS gives this a reload time of (5), or five seconds to insert a new feed strip of 30 rounds into the gun.

Gun stats in GURPS are an odd mix of best case and worst case assumptions.

Accuracy and skill assume the worst conditions.

Reloading appears to assume optimal conditions.

Gate loaded revolvers is someplace this shows clearly.  The Single Action Army has a reload time of 5i, or five seconds per shot.  This is putting it at half-cock, opening the gate, dumping the empties, putting in fresh cartridges and closing the gate.  Try it!  Now try it with your ammo in a gun-belt.

How to simulate the reality?

The rules have footnotes in them that have more detailed loading times that account for obtaining each round individually and how many actions it takes.

But not for strip or belt feed nor does it account for difficult actions, like the Hotchkiss.

Again, we have a rule in the main skill section.  Gunner/TL is a DX based skill normally.  The rules mention rolling against a different stat as circumstances might require.  So, rolling against your Gunner/TL skill against IQ might be what we want here.  My potential house rule would be:  A failure adds 1d-1 seconds to your reload time.  A crit fail adds 5d seconds to the reload.

The detail and realism oriented GM will have to learn about individual guns and make notes available to the players about this.

Most of us just use the numbers in the table.