Sites on barrel question or sites on hand rails?

[smellycorpse]

Doing a build where i was wondering if its better to put the front site on the barrel 20"(hbar) or put the sites on a rail gas block?
what are the pro's and cons of each?. personally i would prefer using a low profile gas-block, hiding it under the hand rail 12" to 14".

newb question, i did a search with no answers

 

[winnipegger]

personally i would prefer using a low profile gas-block, hiding it under the hand rail 12" to 14".

Do this then man.

If it's what you like the look of. Although use a high quality railed handgaurd so it holds zero and doesnt rattle around.

 

[smellycorpse]

but is there any cons to having the site on the rail beside having a loss rail?