Hanging a punching bag in the basement
I read some of the comments here and tend to agree with several points raised.


The 2x6 pieces should be 100% tight and snug to the bottoms of the joists above. It looks like you tried to screw them into place without a clearance hole in the 2x6 which is what could lead to the type of fit shown. You should at least remove and reinstall them correctly.
You could do better than the screws you used by using some lag bolts instead. These will need a washer under the lag bolt head, a clearance sized hole through the 2x6s and a pilot sized hole in the joists. The clearance hole allows the lag bolt to pass through the 2x6. The pilot hole is the inner diameter of the lag bolt threaded region. I suggest 5/6 x 3.5" sized bolts. The bolts and washers would look like shown below.





You need to secure the chain to spring connection better. As it is now the chain could jump off the spring hook under robust usage of the punching bag. A better way would be to use a short bolt two washers and a nut to fasten the chain link to the spring hook. I suggest using at least a 5/16" diameter bolt if not even a 3/8" size. It may be necessary to spread the chain link to get the bolt through.