well only buy caps under 100
well for me i buy individual caps
for example ill buy 5 individual caps every day(or 10)
and open them the next and boom! 1 cap gun

well i saw this thread posted somewhere( i forgot where) and there was this strategy
it is buy 1 capsule (individual) from every eruo weapon there is going from the top of the page to the bottom. or from the bottom to the top and open all you caps
if you get nothing do it again. he said you should get 1 cap gun every 2-3 times you do it
dont buy the capsule guns you already have.

its a pretty weird strategy but it worked for me! but i won the sw1191 XD
i did it again and won the Bizon arachne
it takes me about 4-5 times though to get a gun (its a random gun)