How to edit weapon.dat :

1. Open your GTA SA Directory (My example E:\GTA SA Folder)
2. Open data
3. search weapon.dat or weapon
4. open using Wordpad or Notepad
5. find your weapon to edit (example : SNIPER) using ctrl + F 
6. drag all SNIPER data, copy this line and paste to SNIPER data :

#$ SNIPERRIFLE		INSTANT_HIT	40.0 100.0	358	-1		6	sniper		1	 125	0.7  -0.05  0.2 	0  0	0.75 1.0 	 6 17  7	6  17  7  99	A014
$ SNIPERRIFLE		INSTANT_HIT	100.0 100.0	358	-1		6	sniper		20	 125	0.7  -0.05  0.2 	1  300	1.0	 1.0 	 6 14  6	6  14  6  99	A014
#$ SNIPERRIFLE		INSTANT_HIT	60.0 100.0	358	-1		6	sniper		1	 125	0.7  -0.05  0.2 	2  999	1.25 1.0 	 6 17  7	6  17  7  99	A014



7. save or ctrl + s
