Joshua, Every deal is different. Go to the description page of the firearm you want. Have all the information on the firearm you want to trade. Then click on "Trade with Gurney" in top right corner of description page. Populate all information on trade request that pops up. Get BUDs response and make your deal. To answer your question you can trade one caliber firearm for another caliber/type of firearm.

use this link budsgunshop.com/catalog/contact_us.php?printForm=trades But you will almost always be able to get more with a local sale

Joshua, yes. You find any gun that you want, click the "Trade with Gurney" link in the listing and input your trade information. Buds will send you their proposed trade value to consider. You can also enter your info here for a quote from Gurney : budsgunshop.com/catalog/contact_us.php?printForm=trades