WTK: Lock Problem

[oprod]

Ive got an mgo8/15 that occasionally during the course of the cycle the lock failes to move upwards the last 1/32 or so. It then hangs up on the sideplate cams until the lock is physically moved upward. Im talking of course about the front of the lock that moves up and down. I have tried two locks in the gun and both do the same thing, though one not as much. is there a problem with the knuckle joint? Could the problem otherwise be in that the locks need the metal built up just a tiny bit where the pivot arm and the lifter arm meet( on the lock itself).

[IMBLITZVT]

Sounds like a weak recoil spring or a burr to me off hand... I would not think it would have anything to do with the connection arm. I am sure others will have more of an idea than me.

[dwmmg08]

Did you get a copy of the Devils Paintbrush with the troubleshooting section in the back? What you are describing sounds like the 3rd position stoppage, which can be for a variety of reasons. One is not enough tension in the recoil spring, another is crossfed cartridges in the feedblock, another can be burrs in the lock or even a thick rimmed cartridge. I have had thick rimmed cartridges before, especially in 7.62 Russian ammo, but usually increasing the spring tension is the remedy you need to try. You'll want the Devils Paintbrush if you don't have it already!

Hope this helps, they're great guns to shoot!


Glen

[amafrank]

another possibility is that the original feed arm on the feed block was broken off as a demil. This was commonly done back in the dark ages to make the guns unusable and therefore safe for the govt to give to legion halls, VFW's etc. When they are repaired the most common thought is that the feed arm is setup 90 degrees from the other arm and if done that way you will have problems feeding. The rounds won't get pushed far enough over to feed right. The other extreme is for the feed arm to be repaired too far in the other direction causing the round to hit the stop in the feedblock before the action is in position. That will cause exactly the problem you are describing.
Another possibility is that the bumper on the barrel (the brass ring at the front of the square block) has come loose and is hitting the trunnion before the gun is locked up. It could have a shim that is too thick as well. The bumper is there to stop the action before it goes too far into battery. It helps line everything up so the extractor will pick up the cartridge in the feedway without excess drag.

Hope something there helps

Frank

[oprod]

Changed to another lock and everything works fine. Im thinking it is just the minor fitting of locks to each gun that the smiths did back then. Franks got me wondering now about if I should check all my maxims' barrrel and lock combinations to see if i have anything potentualy disasterous... never had a problem but the cost of these things you sure dont wanna mess up an investment.

[bmg17a1]

To clarify the possible issue with the brass collar on Maixm barrels, there is no relationship between the collar and the headspace with the 08s or the action of the lock in the recoil plates, except under extreme circumstances as noted below. Altering the "thickness" of the collar, so to speak, with adding or removing shims, or unscrewing it or removing metal from the backside, moves the entire recoil/barrel assembly forward or backward in the receiver. This directly affects three specific mechanical relationships: the gap between roller and the crank; the position of the drive pawl in the cutout in the lefthand recoil drive plate; the distance of the extractor face from the face of the feeday in the feedblock. There should be at least .065" play in the feed shuttle without a belt in the feedway to accomodate belt thickness, and this dimension can be modified by adding or removing thckness to the collar, as moving the recoil plates forward or backward will move the cutout the same distance in either direction in relation to the drive pawl. If the collar is too short, it is possible for the extractor to hit the feedway face on rising with a round in the chamber, but this also is unusual, but easily checked.
Adding shims or a collar that has unscrewed a bit will move the entire recoil assembly backwards, and if too much "dimension" is added the crank can stop on the roller, effectively keeping the extractor below full vertical extension. This is extremely unusual, however, and equally unlikey. There are other causes of the extractor not fully rising.
There needs to be a gap between the crank at rest and the roller, which can be increased or decreased by changing the width dimension of the collar.
I would seriously advise against altering the lifting arms of a lock for any reason. The problem is not there if the extractor is not rising fully unless there is evident damage to the arms or the extractor. Disassemble the lock and see if there is something inside the body that is blocking the extractor or the movement of the firing pin. Since a different lock functions, apparently, a thorough disassembly and cleaning of the suspect lock seems in order. Hope this helps.

Bob Naess