The Ross could stand up to the mud and the crud, but what it could NOT stand up to was reject British-made ammunition which had failed at Proof and was too much oversize for ANY chamber in issue.
There are SO many legends and SO much misinformation floating about regarding the Ross that it can be very difficult to sort-out the good stuff from the foundationless legends.
I knew exactly TWO men who used the Ross in the horrific rifle engagement when the Gas came through at St. Julien during the Second Ypres battle. They were Pte Alex McBain and L/Cpl Robert Courtice and both were with the Reserve Company of 8th Battalion, "A" Company. This was the single Company which went up THROUGH the gas when the French Colonial Line broke. The fight was ONE COMPANY against at least a couple of Divisions which Jerry was trying to shove through that gap. Both men fired their Rosses until they were too hot even to touch in order the reload them. They then used pickup rifles and ammunition from casualties and fired those until they were too hot to touch, then continued, using their own rifles. That isn't USING the rifles; that is PUNISHING them. And the rifles took it. But those men, both of whom later were executives of the GWVA and Founders of the Legion, were using their Rosses with good ammunition. I tried to get some "inside poop" on the Ross problem during my interviews with these men, but neither man would budge: they both remained confirmed advocates of the Ross Rifle and both denied that there had been ANY trouble with their rifles during that action. Indeed, Private McBain very nearly became violent when the issue was raised, shouting that "there was nothing wrong with the God-damned Ross Rifle; it's all LIES!" Being that he had used the Ross in combat..... and that I was only born about 30 years afterwards...... I'll take his word! We must look elsewhere for our solutions.
There is NO truth to the tale that Ross chambers were "match-tight"; the reamers used were PRECISELY copied from the reamers in use at Enfield, BSA and LSA and were made by Clymer, which company has been making specialised precision reamers for more than a century now. The DIFFERENCE came at Proofing: the relatively light Lee-Enfield barrel and Body ring actually EXPANDED about 2/1000 of an inch during Proofing, whereas the heavier Ross frame and barrel DID NOT. The result was a very-slightly smaller chamber in the Ross, although one which still would accept ammunition made to Maximum specification. Further, Canadian ammunition was NOT specially-made "undersize" ammo; it was simply held to the LOWER LIMIT OF TOLERANCE, as had all Canadian rifle ammunition of the period. You can prove this for yourself by getting a decent micrometer and a collection of original ammunition covering the entire Ross Rifle period. The ammunition was FINE.
Yes, the chambers of many Rosses were relieved, leading to some of the horrors which are ejected on the range these days. That was well-advertised at the period. What was NOT well-advertised was the simple fact that the chamber of the Lee-Enfield ALSO received a new specification early in 1916. The ammunition being issued -- the stuff which jammed the Rosses -- was percolating through the system and problems were starting to show up with the SMLE rifle as well. The solution was to tighten up on ammunition specs AND make bigger chambers for everything. "Battlefield conditions" became the scapegoat and "cruddy ammunition" was ignored carefully!
How good IS a Ross? I don't know. My own full-length rifle is one of the rifles from the old HMS CANADA and has markings to the 16th Battalion; these indicate that it COULD also have been at Second Ypres, a mile or so away from the engagement in which Courtice and McBain were engaged. The rifle itself is VERY early production and bears a serial of anomalous type rather than the standard military Ross 3-part number-letter group-year marking. With carefully-handloaded ammunition and very good shooters, off the sandbags, it has repeatedly shot sub-half-inch 2-shot groups at 100 yards. These include the rifle cutting its own bullet-holes. This was done WITH witnesses present. It is the single most accurate rifle I own.
Just trying to clear up some of the fog.