The ONLY way to legally possess a firearm after a federal conviction is by receiving a Presidential Pardon.  There is a very unique way in writing the petition, especially if this is the only reason why you see a pardon.  Yes, it sucks that a conviction, even a non-violent, low level, first time offender conviction results in forever being forbidden from possessing a firearm.  It is extremely rare to receive a grant of clemency.  It is even tougher if the only reason that you want a pardon is to legally carry.  

There have been very few cases that have successfully explored the impact that this has on the second amendment and only one Supreme Court case that struck down any avenue for the restoration of gun rights after a federal conviction.  

Back in the day, ATF used to restore these rights until Congress cut off funding in the early 90's leaving a pardon as the only way to seek relief.

Obviously nothing is guaranteed.  I'm sure your criminal defense attorney told you that.  However, preparing the petition correctly by an expert will increase your chances of having an OPA attorney evaluate it carefully and maybe recommend it favorably to the President.  Even if it's presented to the Presidentremember under the Constitution, the President can decide how ever he or she wants.

My role is to try to increase your chances using the inside knowledge that I have.