I think that rifles that were originally finished in Suncorite were Parked first. Many arms made during WW2, most FTRs, and all No. 4 Mk. IIs were Suncorite finished. This includes Brens, some Stens, pistols. As far as I know, the Brits are still using it, or something very much like it. If Suncorite is removed from a FTR, there may be original finish underneath, but it may also be worn. Suncorite is a legitimate original finish, so removing it may well detract from as-issued condition.
Wire wrapped SMLEs were intended to be extensively used for launching 36M grenades, fitted with a gas check, from the cup discharger. Any SMLE could be fitted with a discharger, and on active service might be; the wire wrapped rifles may have been intended more for training purposes. Launching grenades places a lot of stress on the rifle, and there was a slight risk of barrel failure, which is why the forends were wire wrapped. In use, the soldier assumed a kneeling position, and the rifle was supported unside down at about 45 degrees, ideally with the butt against a sandbag. Hands were to be kept clear of metal parts, trigger was pressed with the thumb. There was a shutter on the cup to bleed off gas, to control range. A blank cartridge was used. The bomb was started into the cup far enough that the lever was held in place, the pin was pulled, and the bomb seated all the way. The manual describes interesting drills to unload a bomb without firing, and what to do in the event that the grenade is not launched, but the lever is released. Interestingly, the 1936 manual has all the drills for grenade launching, the 1942 edition doesn't mention it. Grenades were rifle launched extensively during WW1.