.050"what does the firing pin protrusion measure?
Is there a brand in particular you're looking for ?
While your rifle is technically a 1600 (520mm barrel), you won't find much this number referenced...
You can check for "Husqvarna Small Ring Mauser" (not the 94/96 type), Huskvarna (or Husqvarna), Carl Gustav 1900 etc...
Anyhow, here's a little list;
Weaver = F = 46, R = 55 (for the Grand Slam ad an "S" before these numbers).
S&K use the F = 46, R = 55 denomination too
Warne = F = 898, R = 828
Leupold 1 PCE = STD-HC 49989
There are others, but you can work from there...
Just bought a left hand HVA Carl Gustaff 1900.
the scope is a little forward to my liking.
is there a mount that i can find to mount the scope a little further back?
what model do i search for?
Which base(s) are you using ?
Then, try the Weaver # 55 (S55 for the Steel Grand Slam) rear and #46 front (S46 for the GS). The front #46 have two slots. Never got a problem with these, but there is an extension #402 for the front but I never used it myself.