77/22 Bolt Sleeve flange ???

[Stump Buster]

I was looking at my two 77/22's in 22WMR tonight and noticed one has a bolt sleeve with a flange on the left side (like the borrowed picture below)...

and the other has a bolt sleeve without a flange (Like in this borrowed picture)...

Is this strictly cosmetic or is the flanged sleeve a generational upgrade that serves a purpose? I'd call ruger tomorrow, but it's the weekend and I was hoping someone here would know. (eta: Just checked my 77/357 and it has the flange too, not sure what that means, just more info to share with the masses).

Thanks!

Stump

 

[Mobuck]

On the 98 Mauser, that flange defected particles blasted out if a primer or cartridge case blew.

 

[Stump Buster]

That makes sense. Does anyone know if Ruger doing this now for all their latest 77/17, 77/22, 77/357 & 77/44 models?

 

[45flattop]

Not a clue why that is so Stump, but my blue M77/22R vintage 1998 has the
same flange and yes that feature called by some a shroud whether accurate
or not was to deflect a primer gas puncture. It didn't appear on a Mauser
until the M98 series, previous models lacked the feature such as the
M96, M95 etc. It is likely cosmetic on my .22LR M77/22 since I cannot
imagine a case head blowing out on a 22RF case but I still never shoot
without eye protection so if and when it did, with luck I'm safe.