The interesting thing about most of the usual sear tricks to get the gun to fire auto, was that a lot of the C1A1's had short trigger plungers installed, and only needed the C2 selector to run properly.
Years ago I saw some CAR guns where C1's and C2 had swapped the lowers and upper, to give a select fire rifles, and semi-auto bipod heavy barrel DM guns, the C7's came shortly after so I only saw it once while watching a jump/FTX at Julliet Tower when I was supposed to be doing something else. Back as a 17yr old reserve Artilleryman, I dared not ask who/what/where least the death dealing jumpers strangle me (funny how life experiences change ones views)
I saw one of the C1's with C1 Sniper Scope in Ottawa at Connaught - never figured out where it came from, it showed up for a weapons display with C3's while on my SACC.
The chipmuch cheek -- later when I bought my own (Aussie L1A1 with mint CF furniture I added), I found if you actually got the proper stock, it pretty much dealt with that (that gun sadly was sold and deactivated by the new owner).
Later on in '94/'95 WO Tom Ahern (then freshly promoted out of JTF-2) tried to get some C1A1's as DM guns for A Coy 1VP's (he knew the CF was not going to buy HK PSG-1's or KAC SR-25's for this) upcoming deployment to Rwanda (which was scrapped after 3Pl flew to Uganda to spend 35 days in a hotel) as secuity for the DART, and it became unworkable due to few of us knew anything about the C1, and whomever had them did not want to release them (despite releasing NIB C8's and Pistols from warstock to DART, seeing mint No1 MkII* dumped in CLP and the decal pealing off them all made me want to cry as my own personally bought 9T3534 Mo1. MkII* did not have one).
In Iraq we conujured up a bunch of FAL's in various flavors (the Aussies loved to make 10-12" guns) however I sorted thru some of the full length Para ones we had to make a DM gun, and none short very well even with match ammo (it was hard to get fixed stock guns, but Para folders seemed in easy supply). An ex-SASR buddy of mine ended up with a 16" gun that filled our DM role, until BigRed got me the Hk21A1, and I lived with a beltfed DM gun
(sub MOA with belted M118LR and a S&B Short Dot).