Longer barrels and heavier guide rods do not reduce recoil...what they reduce is muzzle rise/flip. If your pain stems from the twisting of the wrist caused by muzzle rise/flip, then they will help. But with the issue being your back, I do not see how they could help you in any way to reduce your pain.
Big Dawg No. 1431
Carolina Glocker No. 1431
"Freedom is a system based on courage" (Charles Peguy)
"Know where the attack against you is likely to come, whether on the street or in court, and have a proven counter already in place" (Mas Ayoob)