I can live with or without the slamfire feature.
Be warned though, there are 4 types of trigger groups for M37/87 shotguns.
Slamfire (M37 until 1975, excluding military sales), non-slamfire (Post 1975 and the Model 87), and thirdly, the lesser known LAPD trigger, one cannot even move the fore-end back until the last shot trigger pressure has been removed. (police department option from the factory) But with this LAPD model at least, one does not waste a shell as all you have to do is release the trigger and press again to shoot, assuming a live round is chambered. With the second non-slamfire model, if you have not released trigger pressure and pumped it into battery, one has to release trigger pressure AND pump the action again to bring a new round into battery, possibly ejecting a live round that one could not fire,
(and wasting precious time) THEN ready to fire.
Then there's the real wildcard, triggers modified to slamfire, regardless of year of manufacture. (or military surplus)
I've discussed the slamfire feature with Ron Sharp at length. He discourages this use with older shotguns especially. His thoughts on this, the linkage to do so is rather weak compared to a Winchester 1897 or "newer" Model 12 that also slamfire by design. With an older worn out M37 Ithaca, one could possibly have an out of battery discharge purely due to worn out parts.
Please don't have an bad accident trying to prove/disprove these words!