I see many vendors offer free shipping if you buy XXX numbers of rounds but I would like to buy an assorted group of different ammo to see how they compare.  

I have Colt SP1 with a 1:12 twist so my choices for ammo are a little less but I would still see how much difference I would see if I paid a little more per round but shipping costs making it not practical to order a few boxes from here and a few from there.

Anyone know of a vendor that offers free shipping on combined orders?

Most I see that offer free shipping is over a $$ amount not certain rounds of ammo.

That said I don't see many free shipping offers.

If you are getting "free shipping" you are instead paying for it in the price of the ammo itself.

I haven't checked their stock lately, but Cope's Distribution offers $9.99 flat rate shipping on any/all orders...which is almost free.

That will work for me - Thank you!!!

Palmetto State Armory offers free shipping every few weeks.  Good prices too.