The same 2 cylinders? Could be a timing issue. Take a look at the primers to be sure the strikes are centered.

Going shooting this Sunday. Will check out your theory. If it is timing what is the fix? Thanks for the reply.

Fired 50 rounds of Winchester 240 Gr. 44 mag today at range with no problem. Problem could be certain manufactures ammo caused misfires?

Could be that your first batch of ammo had harder primers (different manufacturer?). You could also have a marginal hammer spring. If you have ammo that works though, I wouldn't mess with it.

Going to try Hornaday 44 mag FTX 225 gr. Personal Protection next. Will let you know!

I have a model 29 exactly like yours, except mine is blue. Suggested improvements to consider:
1. Get the barrel "magnaported"
2. Replace the rear factory sight with a "millett adjustable"
3. Install a set of hogue finger groove grips for comfort & control
4. Feed it a steady diet of: 240/250 grain lead swc bullets-----8.0 unique---winchester large pistol standard primers---900 to 1050 fps.

Answer to question: Check the tension on the mainspring first. The adjustment screw is located on the lower front strap of the frame grip. Remove grips, find a properly sized slotted tip screwdriver, & turn the adjustment screw all the way to the right, but not "gorilla tight". If the mainspring needs replacement, contact "wolff springs" and tell them you need one to fit the n-frame smith.

I agree with the rest of the contributors, this is most likely an ammo issue. I have not purchased any factory ammo for my hog-killer since purchasing it new in 1977. Good luck !!!!!!!!!