MALFUNCTIONS

[Music] [Music] [Music] [Music] the L saw him go Steve's guns were jammed he didn't have a chance perhaps this little incident had something to do with what we just saw sort of a mess isn't it but a good cleaning we'll fix it a good cleaning soldier sure Steve's gun jammed not hard to see why is it this 37 millimeter is flying artillery the planes job is to get the gun at the right place at the right time and when that instant arrives the gun must fire you bet it's a must to keep them firing just remember that the 37 millimeter m4 is subjected to severe and constant contact with dirt and foreign particles and therefore requires constant cleaning the time to do that is immediately after use it will have to be done with the gun in the plane most of the time but if at all possible remove the gun from its mountings it should be removed regardless at regular intervals for a complete inspection how often will depend on frequency of use and operating conditions this one has been removed be sure the gun is unloaded this is a first always then clean and lubricate thoroughly which means complete disassembly inspection and cleaning of each part with a dry cleaning solvent and finally lubrication with the lubricant correctly applied in the right amount if you know how this weapon works and you'd better know to be able to do a top job of maintenance and repair you readily understand the must of proper cleaning and lubrication there's plenty of sliding friction during each cycle of firing here are a few places you should give special attention the lock frame grooves these two front operating lever cams and the left rear operating cam the contacting surfaces of the tube and trunnion block bushing don't forget these grooves for the breech block in the tube extension and the T slot for the breech block lifting guide and the carrier pin which is subject to severe impact oil the threads of the tube and tube extension use SAE 30 the tube will need to be removed frequently and this will aid the procedure tremendously another point always check the recuperator oil level check this level with the gun at an elevation of 5 degrees and remember that only oil recoil light u.s. army specification 2-3 6d or latest specified oil should be used a few ounces either way will make a difference in the functioning of the gun the oil should just come to the bottom thread of the filler hole if necessary to add oil be sure all the air in the recuperator is expelled do this by slapping the side like this check for any leaks around the front and rear recuperator endcaps be sure end caps are tight here's why this rear end cap is leaking around the piston rod that means a new stuffing box packing and install it carefully like this being sure the rest of the stuffing box group is assembled correctly when putting the packing over the threads on the front end of the piston rod be sure to screw it down and seat it with care and that recuperator piston rod is supposed to be smooth don't scratch it when tightening the stuffing box nut when replacing the endcap use a small amount of white LED on the threads don't get any on the first few threads why to prevent mixing any white LED with a recuperator oil keep that oil level right and you'll prevent trouble remember too much oil means a sluggish gun and too little means severe recoil and loosening of the gun on its mount when lubricating use oil ax s 777 which has rust preventive qualities if this is not available use oil for aircraft u.s. army specification - - 7m this oil gives little or no protection against rust or corrosion and must be renewed at least every 48 hours in cold weather when the gun is taken indoors from the plane Moisture will condense on the cold metal and cause rust clean and oil immediately after the gun has reached room temperature it must be wiped free of any condensed water vapor and oiled again in wet or damp climates take particular care that rags used to wipe parts are dry and don't handle dried parts with bare hands he was an oily rag if a weapon is to be put out of service for more than 48 hours oil all parts with a excess 674 when placed in service again it must be cleaned and properly oiled with AXS 777 proper maintenance will do much in preventing malfunctions but of course some will occur you'll find using dummy rounds the best way of locating where in the cycle of operation the trouble lies let's try this gun and find out if anything is wrong there very definitely seems to be trouble the round has jammed on its way into the feed box note how the bell plink has jammed in these raceways of the belt guide because a bent belt link here's another cause watch the action as the loading handle is pulled back the feed slide isn't being drawn across the trouble is right here in the adjustment of this loading handle rod nut the nut is on too far the cam follower must line up exactly with this left-hand hole of the loading handle cam here's why when the nut is too tight the follower will not allow the cam switch to move to its normal position therefore when the cam is pulled back the slide will not be moved to the right as it must be to load the gun so place it right not too tight or too loose but so the follower lines up with the hole here then insert a cotter pin to keep it locked in place any jam that will hold up the feed slide will break the feed lever or the tube and tube extension will be held out of battery due to the feed lever operating stud being caught on the feed lever we can see what's happened by use of a cutaway use extreme care in repairing first remove the screws holding the feed box and then lift the feed box off carefully thus clearing the feed lever and allowing the tube and tube extension to go back into battery just remember that the full power of the recuperator spring is pulling on that tube extension one more cause of failure to feed an improperly installed magazine be sure the two halves line up correctly when bolted together at the top if the parts don't line up this will happen keep the supporting and guide rails clean remember a gun is only as good as its feeder now let's see what goes on here pull back the lock frame all the way and release it right the lock frame slammed forward again well let's find the trouble remember how the gun operates the lock frame is caught and held by the carrier dog therefore let's have a look inside we remove the feed crank and feed slide lever here's the trouble alright the carrier cam lug is broken off which means that the carrier will not be forced up to engage the catch and therefore the carrier dog will not hold the lock frame to the rear a broken carrier spring will also keep the lock frame from being held back here it can be seen that no spring pressure is being exerted on the carrier dog and it will not be forced to engage in the notch of the lock frame take a look also at this carrier catch the spring in this one is broken note that the catch therefore won't come back into position and the carrier will not be held up result the carrier dog won't engage the lock frame another point check the driving spring assemblies we lose this one which has been cut away for illustration remember that when the lock frame is moving back the driving Springs are moving back in the housings and binding of the springs will keep the lock frame from going back far enough notice that this rod can hardly be pulled a close look tells why all right look at that dirt and grease the dirt gets in through this hole in the end of the housing and around the rod when the lock frame is held back and the tube extension is forward exposing the rod and of course any dent or bend in the housing or tube is going to result in binding so check those driving Springs and you can usually tell if binding is occurring by pulling the lock frame back if it pulls hard and the spring squeal you'll find your trouble there here's a good way to clean the assembly first use dry cleaning solvent and pump the rod and spring up and down then drain it and do the same using a light oil if this doesn't work replace the assembly or take it apart and clean it of course a broken spring will also cause binding excessive friction of the lock frame sliding in the receiver will also keep it from being held to the rear with the driving Springs disconnected we can see here that the lock frame is binding badly and can't move easily to the rear of the receiver clean the lock frame slides and the sliding surfaces in the side plates of the receiver then inspect the surfaces for bad wear or burrs use a light to locate bird surfaces it's a good idea not to use your finger until you know what's in there here's what kept that lock frame from sliding back probably a piece of very hard gravel was blown in here during a takeoff or landing it will have to be stoned and carefully to if you have a gun that fails to load look first at the lock frame see if the carrier assembly will hold it back and whether or not it is blinding so that it won't go back far enough to be held by the carrier dog use that knowledge of functioning again the lock frame charger starts the cartridge into the chamber and the extractor guides at the rest of the way so that the lock frame has to be to the rear of the round if the carrier is slow in coming down the round won't be positioned correctly and the result will be a jammed round in the tube extension as we can plainly see here with the feed box removed a bent carrier a binding carrier pin or weak carrier spring will do it sometimes you'll find this causing the gun failing to load the round is not positioned in the extractor because of this damaged rear lip the lips must be smooth and free of burrs remember what happens when the trigger is pulled here's a refresher the trigger lever rotates and the connector is drawn back the sear is rotated and the hammer released here's the action on the lock frame notice how the sear spring returns the sear so the hammer will be caught again we remove the sear spring and replace the sear now watch what happens the hammer is not held back but follows forward as the operating lever rotates forward and look for trouble here when there's failure to fire this trigger bar must move freely to rotate the trigger lever when it's in a mess like this it won't move easily and the gun may not fire if it does fire a runaway gun may resolve a bend in the trigger bar fixes things up nicely - when the trigger moves easily without any pull see if you don't find the feed box assembled on the receiver improperly when it's like this the trigger bar will be pulled back a sluggish gun means that the tube and tube extension or the lock frame are returning to battery slowly right we've talked about some of the causes already anything that's going to slow down the action of the tube extension and the lock frame will give us a sluggish gun and check the adjustment of the recuperator piston after removing the oil of course we can see it better on this cutaway this piston is too far forward notice that when it returns to battery the oil slot and thus the oil flow is cut off before battery position is reached that means slow returned and a sluggish gun adjust the piston so that its front face just reaches the front edge of the throttling slots that's where the gun in battery then turn the piston off one complete turn plus just enough more to permit the cotter pin to be inserted now watch the position of the piston as it comes into battery here's extraction the lock frame is held to the rear as the tube extension separates from it you've guessed it if the lock frame is not held extraction will not occur and see what happens if the extractor is broken there goes the case back with the tube extension here it is closed a hole extractor is quite necessary there it is you've not seen all the malfunctions that may occur but we did cover the ones most frequently met seems like a lot but your troubles will be few if you inspect the 37 millimeter m4 regularly and keep it clean and oiled and you can be mighty sure this fellow will thank you plenty when he gets this result it's worth the effort [Music]