Ruger SP101 frame changes

Hi All,

I bought a brand new Ruger SP101 (2.25", .357 mag) last week and I noticed that there is a slight change on the frame. On the brand new SP101, there is a raised piece of metal/boss on the left side of the frame located near the lower right hand corner of the cylinder window.

This piece was not present on my older 3" SP101. It looks like that on the older SP101, this piece of metal was machined off.

On the newer SP101's that I've seen (including my newest one) the piece is not machined off, but it does appear that it is ground down enough to provide clearance for the cartridge case during loading/unloading.

Does anyone know when and why Ruger implemented this change? Is it purely cosmetic or is there an engineering reason for the change?

Here are some pics of my new (2.25") and older (3") SP101s:





Thanks-in-advance!

Maybe it keeps the cylinder from falling off instead of just the one little bump.

Since Ruger frames are cast it is a cost effective way to add the cylinder retention projection. By casting it into the frame Ruger no longer has to drill a hole and then press fit the part in. We get the benefit of the part not shooting loose as sometimes happened. Your frame may also have the new firing pin retention screw instead of the old crosspin.

Best Regards,
ADP3

Thanks for the explanation ADP3!

Surprised it took Ruger so long to change as S&W changed back around 2000 when going to MIM parts.

My SP-101, serial number 575-1047x, has the cylinder retention
projection. Purchased in early 2014.

Interesting.... I didn't realize S&W went that route too. I have a model 60-14 which has the older style frame (but is recent enough to have the internal lock). I googled some images of the S&W model 60 and noticed that they now also have a similar integral boss on their frames.