I recently had my first AR build done and was wondering about putting a sling on it.  The upper was made by Del-Ton and it's a 20" hbar with a 2 rail gas block and a DPMS solid float tube.  Now its my fault that I didn't ask if the float tube came with or without a front sling swivel (all their factory builds seems to have it so I assumed) but anyway, what, if any, issue would I have attaching a front sing swivel on the under barrel rail of the gas block?  Since I won't be slinging this up competition style there won't be any torque on the barrel while shooting so theorectically I should be fine right?

Thanks for the help fellas.

You can find about any sling rail mounting hardware at MI.
http://midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_id=80

Thanks rifleshooter, but my question was actually more in regards to the accuarcy problems I may encounter from using a barrel mounted sling.  Sorry if the original question was vaguely put.

Just drill and tap the tube for a swivel stud.  You may want to mount a bipod someday too....

Is there enough material to put one on with worrying about it stripping out and looking like ass later??  If it is that easy than I will probably do it that way.

Should be thick enough- mine was,  but you can always put a nut on the backside (inside).

sounds like a plan...thanks for the input guys

The free float tubes aren't strong enough to just tap into, the stud will strip out, most likely at the worst time. If you put a backing plate on the inside, you'll be fine. I've found I like the sling on the left side of the rifle vs. the bottom. It hangs better on my back and tends to get caught up less when slinging and dismounting.