Filling system
Turn the knob at the end of the barrel and a screw draws a piston up the barrel, pulling ink in through the nib. Pelikan built its first pen around the idea in 1929, Montblanc's Meisterstück 146 and 149 use it, and it's still how most Pelikans fill today. Piston fillers hold a lot of ink, and most show the level through an ink window or striped barrel. On older pens the piston seal was cork, which dries, shrinks and stops sealing, so a pen that leaks past the piston or won't draw needs a new seal. Later pens use synthetic seals that last longer. Either way, a filler that turns smoothly and draws a full load of water is the thing to ask about.
12 pens we cover.

Montblanc · 1952–present
PistonPrecious resin, 1980s
Modern
$525–$775 typical ask
29 on eBay

Montblanc · c. 1950–early 1960s
PistonCelluloid, 1950s
Post-war golden age
$1,275–$1,625 typical ask
5 on eBay

Montblanc · 1950s
PistonCelluloid, 1950s
Post-war golden age
$725–$1,050 typical ask
11 on eBay

Montblanc · c. 1968–1978
PistonPiston-filling 22x series, 1970s
Modern
$130–$230 typical ask
25 on eBay

Montblanc · 1950s–1960s
PistonGold-nib student pen, 1950s
Post-war golden age
$190–$290 typical ask
24 on eBay

Pelikan · 1982–present
PistonGreen striped, old-style trim, 1982 to 1997
Modern
$290–$380 typical ask
27 on eBay

Pelikan · 1987–present
PistonBlack, old-style trim, before 1997
Modern
$500–$750 typical ask
17 on eBay

Pelikan · 1985–present
PistonSteel nib, old-style trim, 1985 to 1997
Modern
$140–$250 typical ask
27 on eBay

Pelikan · 1956–1965
PistonThird version of the 400, 1956 to 1965
Post-war golden age
$260–$340 typical ask
24 on eBay

Pelikan · 1929–1944
PistonThe first Pelikan, celluloid barrel
Pre-war and wartime
$400–$550 typical ask
10 on eBay

Pelikan · 1985–present
PistonOld-style, M400-sized, 1985 to 1997
Modern
$350–$525 typical ask
16 on eBay

Pelikan · 1997–present
PistonBlack, two-chick logo, 1997 to 2003
Modern
$900–$1,200 typical ask
26 on eBay