J frame Ti cylinder swap problem.

LazarusLong

LazarusLong

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Hello all. Purchased a titanium 340PD cylinder with the intention of doing a cylinder swap on my 642. I've seen a number of people report they swapped cylinders with no problems

I took my old extractor star and put it in the new titanium cylinder. Put everything back together. Only issue is it is difficult to fully close. It seems like the center pin magically grew a couple thousandths and it doesn't like to slip past the detent. Once you get it snapped into the detent fully and closed, it rotates and carries perfectly. Swapped the stainless cylinder back in and it opens and closes like butter.

The only time I've had similar issues it was some gunk under the star, but this cylinder is brand new and spotless.

What needs fitting that would cause this? Thank you for your expertise!
 
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Look at the other end of the ejector rod. Is it hanging up on barrel lug a bit? Possible that the way that every thing makes up and fits together is among it just a bit long. Measure the everything with calibers when assembled.

Also, your new cylinder might have a slightly shallower center hole and that riding on the end of the yoke tube is pressing the cylinder and center of the ratchet back into the recoils shield a tiny bit. Measure from a spot on front of yoke to center of ratchet on SS cylinder and then on TI cylinder.

A .001 can cause nice to become difficult.
 
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What steelslaver posted!

Measurement comparisons is all you need. These are the tiny simple issues that take the wind out of "drop-in" everyone warns about.

Did you compare overall cyl lengths with and w/o star in place?

Compare over all length of ctr pin installed (pushed to the front and flush with star in the back) in each cyl from star surface to front end.

Compare over all length of extractor rod installed in each cyl. from star surface to front end.

Let us know what deviations you find and we can suggest where to take off any excess length.
 
I have dual cylinder gun. Has a 22 Harvey Kay Chuck cylinder and a 22TCM cylinder. I had only fired it a few times in 22 TCM and then poked out the brass as it is a rimless case. Anyway, I break down and ordered some 6 shot S&W K frame moon clips. (high dollar like about $80 for 10) The holes are a tiny bit big for the TCM, but I have a plan for that.

But, anyway I drag it out because I am going to need to machine the rear of the TCM cylinder for the clips. But, wait LOL, I decide to change the barrel first. No problem, get new barrel on and timed and what? Cylinder won't close. Hitting the barrel extension ? Nope. ejector rod tip is hitting on the barrel lug. Needed to file a couple thou off the ejector rods for both cylinders.

Point is lots of times you get lucky. But, sometimes the little variations pop up and needs to be dealt with.
 
Thanks for the replies! I broke out my calipers and for the life of me I cannot find a difference in measurements between my OEM stainless cylinder with ejector rod installed and the Ti. But this story gets better!

I bought a used 342PD off GunBroker, which I received today. The barrel cylinder gap was non existent. So much so that it dragged on the barrel on at least one chamber. It also had a slightly more than normal amount of endshake. When the cylinder was pulled back the BCG returned to normal range. The mad scientist in me had an idea.

I took the 342PD titanium cylinder and put it in my 642 with my old extractor star. Functions perfectly, BCG good and no endshake.

Took my 340PD cylinder I bought from Midway and put it in my 342PD. Fits and times perfectly. Now there is no longer any cylinder dragging, the BCG is acceptable and the endshake it previously had seems to be gone.

I feel like Tuco Ramirez in "The Good The Bad And The Ugly" when he is assembling parts of all the different revolvers to make a good one :D

The 342PD weighs 13.5oz loaded with Gold Dots, Hip Grips and a T Grip.

The 642 with a Ti cylinder weighs 14.2oz loaded with Gold Dots, Hip Grips and a T Grip.

Even now that the cylinders are $140 from Midway, if you scored a 642 at pre panic pricing (think I paid $360 for mine brand new a couple years ago) you're still only $500 into a gun that only weighs 7/10th of an oz more than a 340PD which sells for $850-1000 now if you can find one. Whether the .357 and pinned front sight is worth the difference is up to you.
 

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I once had two N frames, both with nice actions. But one would push off from full cock. I swapped the triggers and neither would push off. Both still nice actions. Just a factor of minute differences in contact surfaces.
 
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