The fast way - Extract everything
1. Open HEK+
2. Open Map
3. Select everything from map
4. Drag and Drop onto tags list - Uncheck "Save Extracted Tag List"
5. Export (Click start)
The harder way (If you don't like having tags you don't want)
(Small Tag)
1.Open HEK+Map
2.Open Weapons, SniperRifle
3. Highlight needed tag
4. Export (as above)
(Full Weapon)
1. Open HEK+ and Map
2. Click Weapons
3. Highlight the Weapon you want
4. Export (As above)
5. Open .weapon In sapien
6. Get list of Errors
7. Open Debug.txt
8. You will get lists of errors. Go back to HEK+ and find the missing tags that are needed
(that's how I would do it)