Question on Barrel Replacement for older RST-4

[jtsteiert]

I have a old RST-4 that is missing the front sight, inquiring through this forum last year I learned that it would be better and cheaper to obtain a replacement barrel and receiver than it would be to have a gunsmith install a new front sight.
I have found a barrel and receiver from a MK II and I would like to know if it will work on my RST-4?

 

[martyj]

If it just the blade part of the front sight they can be replaced and purchased through Ruger.
Alot cheaper than replacing the barrel

 

[contender]

As mentioned above, if it's just the blade, then it can easily be replaced. However, if the base area has been modified, then either way, it's gonna cost you gunsmithing fees. Yes, the barrels will interchange. Just make sure you get the same sight profile, (both being RST-4's) as a different sight profile will cause a different sight height alignment. Accuracy will suffer.
Now, if you swap the WHOLE upper assy, barrel AND reciever, then the swap is easy as well. No issues with the sight height either.

 

[jtsteiert]

The plan is to swap the whole upper receiver + barrel, before I buy this one I want to make sure the MK II mid 90's receiver will fit on my 76 RST-4 frame.

 

[Doc Thornton]

this is not what you are looking for but Numrich Arms has the
stainless 4" standard barrels ("used excellent factory take offs")
complete with fron sight, for $38.95 if you would like a duo-tone look.

Product # 273170