I found a 4516 top end, would it be a plug and play fit on my 457 frame ? I figure this would at least eliminate the plastic guide rod and give me the more machined slide, if it will work. Any input is appreciated.

In short... Maybe!
Only if it's a dash1 or later variant will your idea work. The early no dash barrel will not seat properly within the barrel camming lugs of your 457 frame.

So, A 4516-1 or a 4516-2 will work... An early 4516 with the raised rib atop the slide will not as the feedramp & lugs are too wide for the 457 frame.

Now if what you have there is indeed an early 4516 i think there still might be a way to make it work. You'd need to find a 4516-1 barrel and install that instead of the 4516 tube.

Assuming you have the correct variant, the only other thing you must do when swapping a slide is check the decock timing. I posted some instructions on that procedure some time ago here...
http://smith-wessonforum.com/138950725-post58.html

Otherwise, welcome to the world of "Frankenguns" and we'll need some pictures if your project succeeds.

Cheers
Bill

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Because they don't make a .46

BMCM,
Thanks very much for your input, after reading all your threads if anyone knows, I'm thinking it would be you. My 457 won't actually be here until Monday probably, then I'll check the barrel, I can see what the barrel looks like on the 4516 from the ad the seller has posted. I think I know what you're referring to with the cam lugs. Let me ask this, if the two barrels look the same, does that mean this will work ? I appreciate your thoughts on this. Putting a 639 upper on my 439 was a lot easier, LOL.

Here's a couple pics that might help...

No- dash vs. dash1 barrel, note the wider feedramp and lugs on the no-dash tube. the no-dash is a no-go on a 457 frame.


And here comparing a dash1 to a dash2 you'll note a minor difference in feedramp contours otherwise these barrels re essentially the same with one big exception... The dash1 has a narrower hood or tab compared with the wide hood on the dash two. Either of these will fit your 457 frame but depending on what 4516 slide you come up with you need to use the hood or tab width that fits the slide.

Hope this helps.

Cheers
Bill

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Because they don't make a .46

It is a 4516-2 kit, so you're thinking it will work then ? Other than checking the decock timing it would be a direct swap ?

If you can PM me a link to the seller's add I might be able to ID the variant for you.

Cheers
Bill

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Because they don't make a .46

Luckily the item for sale is a complete parts kit, so I'll have a matching slide and barrel

Yup it'll work just fine

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Because they don't make a .46

PM sent, thanks