Can you replace the barrel on a 4" 66-5 with a 2.5" barrel? I'm sure someone knows the answer. Just asking so no why would you want to do that's or buy a new one. Just a question.

It can be done, but I would suggest just searching for a complete 2 1/2 gun might be easier. To do so would take considerable skill working with S&W revolvers. First of all, the replacement barrel must mount in the frame by the same method as the original (pinned, non-pinned, etc.) and it would require the proper extractor rod and center pin for the 2 1/2 version. to change the barrels properly one would need a special barrel wrench.(Can be done with barrel in a padded vise and a wooden hammer handle through the frame to turn old barrel out and new barrel in, but that is risky without experienceand tweak and possibly ruin the frame. No good.) Would have to know how to set back barrel back properly to obtain correct Bbbl/cylinder gap. Would have to know how to file rear surface area of the barrel to obtain proper gap if necessary. Would have to fit new center pin to new barrel lug. I f all this was accomplished properly one would still be left with a square butt frame countour.although one with proper machining skill could re-shape it to rpound butt configuration. All that depends on finding a 2 1/2 barrel in first place. Not easy. Is hard enough to find a complete 2 1/2" firearm. Might be wise to do that. Hard to come by sometimes, but with a little patience and $ they can be found. Not cheap, but probably more so than the described conversion. Sorry to be so lengthy, just want to let you know what you would be getting into.

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S&W Armorer
Lost in the 50s

As the previous poster noted, you'll need more than the barrel as parts. The expensive part isn't a barrel vise, it's the frame vise to prevent frame damage while removing/installing the barrel. The barrel can be clamped in wood blocks in a vise, so long as the frame is properly supported.

However, the factory doesn't sell magnum barrels and any barrel you find (new or used) would have to be fitted to provide proper alignment and barrel/cylinder gap. You could have the present barrel shortened and an ejector rod and center pin fitted. This would eliminate the cost of the shorter barrel, machine time would work out about the same. Hint: you're shortening the barrel primarily from the back end, the front latch stays in place, the sight might have to move.

A shorter (than 4 inches) barrel on a K frame doesn't improve concealment, it also doesn't provide full length ejection of fired shells. The 4 inch barrel rests against the hip and actully levers the butt of the gun into the body, improving concealment. Shorter barrels make use of heavy belts and proper holsters MUCH more important.

Thanks guys for the upfront info. My 66 is a 4" Round Butt but that is a small part of it. Coming from shooting Dan Wessons mostly you get used to this type thing being easier. Just saw some 2.5" barrels and was wondering if it was worth putting one away for a bad day. Guess not. I really do like the 66 after putting Ahrend grips on it. Feels right in my hand.

If, and that's a big "IF", you could find a 3" barrel, you could have a qualified gunsmith do a barrel swap with no extra parts needed. A 2.5" barrel would require a new/shorter ejector rod. I just had a 4" M65 rebarrelled with a 3" barrel. Set me back $90 for the barrel plus $60 for the install (with all the work noted above for proper setback, cylinder gap, forcing cut smoothed). That's not mentioning the 4 months the 'smith had my gun for the job he quoted as 2 weeks. I plan on selling off the 4" barrel to differ some of the $150 this project cost. I got my 3" barrel from Brownells, you could try them, or Numrichs, or Midway.

So far only 2.5" barrels around, not really a bad price for a 3" - 66. Have to keep my eyes open.