My new R-1 300 WinMag has has 140 rounds through it consisting of Federal factory, W780 handloads (150s, 168 & 180s), A4350 150s, H4831 150,168 & 180. Bullets have been Barnes, Hornady, Sierra & Nosler.
Still have yet to clean it and it has yet to malfunction.
If you want a malfunction, ease the bolt closed. Just like any semi auto, you gotta let the operating system close the bolt.
I also own an MR-1 that has seen 500 plus rounds of whatever I can get the cheapest (no steel case).
Just goes bang everytime I pull the trigger and has never been apart since the initial tear down, cleaning
and lubrication.
It is amusing that all the AR boys are rushing to create piston guns. Guess what the OS on the R-1 & MR-1 is ? AND it is a shorter stroke system (cleaner)!
An issue with no evidence to support it. As I recall the USMC 12 bore Bennelli (which uses the ARGO system) passed the 5000 round test, the mud test and water immersion test without a hiccup.
The one fault the R-1 has is that it is tough on case rims. They still seem to work fine but look a bit ratty after 5 reloads. I do not full length size as all 300 Winmag fl dies set back the shoulder which contributes neither to accuracy or case life.
Only new factory Winchester brass is used for hunting loads after neck sizing, trim to square up and chamfering.
Just an aside, but still waiting for my Winchester National Match M-1 to malfunction...and it's on its second barrel !