Does the Gerber Magnum LST Jr. weigh much?
Not at all, which is one of the main reasons that it is my primary EDC knife. I have a couple of Gerber Paraframe knives (as well as a couple of the Mini's) that I actually prefer, although their width and mass make them much less practical for me.
Looking at Gerber's website, it appears that some of their specs are screwed up. The shape of the drop point on my LST Jr. appears somewhat different than the current version shown on Gerber's website, although not enough to justify the difference between my measurements and theirs:

Gerber LST Jr. - Serrated
43g
2.75" Blade
6.25" OAL

Gerber Paraframe Mini - Fine Edge
40g
2.25" Blade
5.25" OAL

Gerber Paraframe - Serrated
76g
3.00" Blade
7.00 OAL
My LST Jr. is probably ten years old (or more) but even still I can't imagine that the current version actually weighs over 90g as the website claims.
I also carry a BSA Hot Spark Fire Starter on my keychain. How do you like it?
The few times that I've actually used it, I was
eventually able to get a fire started, although I can generally get fire with my standard firesteel in the first or second stroke.
Jim