Although you did not provide good details on the drum magazine itself, I'll take a stab at it.
1. 75/100 round drums have key wind springs to allow easy load through the hinged lid, when the spring is released. After loading the magazine in the appropriate slots, the key is wound to provide the pressure required to rotate the slots, advancing the rounds into the feed. It is not uncommon to underwind (or overwind ) the spring.
An underwound spring may not have the necessary pressure to continue feeding the full load of rounds.
Test Procedure. Fire 10 rounds, rewind, Fire another 10 rounds, rewind .... repeat. See if this doesn't solve the problem Work at determining the correct wind for your magazine.

2. Your loading pattern may be incorrect and does not allow all rounds to rotate properly.
Test Procedure. After the jam, remove the magazine. (Clear and make rifle safe) Open the hinged lids and ensure that the rounds are still in the proper positions to continue feeding. Correct the loading process.

Keep us posted.

 

I'm sorry that is my bad. The drums are a 75 round Romanian wind up I think. I looked on YouTube on how to load the drums. Basically this is the video I went with on how to load it. http://youtu.be/9wo5QwwA10s. What other information do you require to know about the drums? Also, the pictures I posted were done as I manually cycled the bullets to recreate the jam as if I were shooting the gun. It jam even by manually cycling it.

How did you guys learn how to troubleshoot drum magazines?

 

I just shot the new drum today and it worked flawlessly. I followed the instructions on this YouTube video http://youtu.be/-ioQ499lFoE

I only shot the new drum once and I plan on shooting it again. I wound the new drum up 5 half turns and I couldn't wind it up more past that.

The old drum that I bought used is another story. I wound that thing up more than 5 half turns and it kept winding and winding. It never stopped winding. So I settled for 5 half turns and shot the thing and it still jammed

 

Here is the other picture

 

I just got done shooting the new drum magazine following the loading procedures in the video and it fed all ammo flawlessly. That's twice now that I have shot the new drum magazine without failure to feeds. I am really thinking there is something wrong with the old drum magazine. I can only wind the new drum 7-8 half turns and then it stops turning. The old drum doesn't do that. I can sit all day long and wind that old one up. Where do I go from here?

P.S. If i were to store these magazines for future use loaded up but no spring tension would they still work? Or would they fail to feed? In the video I watched the guy pushed down on the rounds to get the pressure off of the spring inside the magazine lips.

 

I just got done shooting the new drum magazine following the loading procedures in the video and it fed all ammo flawlessly. That's twice now that I have shot the new drum magazine without failure to feeds. I am really thinking there is something wrong with the old drum magazine. I can only wind the new drum 7-8 half turns and then it stops turning. The old drum doesn't do that. I can sit all day long and wind that old one up. Where do I go from here?

P.S. If i were to store these magazines for future use loaded up but no spring tension would they still work? Or would they fail to feed? In the video I watched the guy pushed down on the rounds to get the pressure off of the spring inside the magazine lips.

Yes, with no pressure there designed to sit indefinitely. Your old drum seem like a lemon.

 

I disassembled the drum and this is what the spring looks like. When I wind the drum up and release the tension on the drum it doesn't make that loud "pop" sound that the new drum makes. Does the middle piece that connects to the spring have to be in a certain position? Or does that matter?

 

Yes, with no pressure there designed to sit indefinitely. Your old drum seem like a lemon.

So when I load the drum and turn it half way to put tension on the bullets and then load the drum the rest of the way that half turn to put the bullets up the chute of the drum won't hurt the spring if I left it that way indefinitely?

 

I think I found out what is wrong with the magazine. Towards the front end of the magazine there is a metal tab like a rivet or a pin that pins into the spring. The new drum has this feature but the old drum is ripped off. I took the old drum to a gun store and they said it was acting like the spring was catching but not holding te tension. Is this old drum fixable?

 

So when I load the drum and turn it half way to put tension on the bullets and then load the drum the rest of the way that half turn to put the bullets up the chute of the drum won't hurt the spring if I left it that way indefinitely?

No tension completely released then, indefinitely.

 

I think I found out what is wrong with the magazine. Towards the front end of the magazine there is a metal tab like a rivet or a pin that pins into the spring. The new drum has this feature but the old drum is ripped off. I took the old drum to a gun store and they said it was acting like the spring was catching but not holding te tension. Is this old drum fixable?

Sounds like it's fixable.

 

No tension completely released then, indefinitely.

Huh...the guy at the gun store told me that putting the 5 bullets in the chute and turning the key halfway is part of the loading procedure and I can leave it like that. Since I asked him why the drums were jamming when I fired them he said I didn't load it right because I didn't put the half turn tension on the bullets. Also how would I fix it? Spot welding?

Here is the instructions I received in the box.

75 Round Chinese Magazine Instructions

TO LOAD MAGAZINE
1.) Unlatch and open the rear cover. Depress the spring loaded button in the center of the drum and turn the spindle clockwise until the magazine follower is returned to the beginning of the spiral track.
2.) Insert five (5) rounds into the slots located nearest the top (column) section of the magazine.
3.) With five rounds loaded, hold the spindle firmly in place with one hand. With the other hand, wind the spring tensioning key (located under the spring loaded button) CLOCKWISE three (3) clicks.
CAUTION: Hold the spindle securely while applying tension in order to prevent it from slipping and catching your fingers.

4.) With the spring tensioned, quickly release the spindle. The five rounds loaded previously will be pushed to the top of the magazine, and the last round will hold the spindle in place.

5.) At this point you have the option as to how to load the magazine. If cartridges are dropped in the remaining slots, the total magazine capacity will be seventy three (73) rounds. Alternately, if the procedure described as follows is used, the total capacity will be seventy five (75) rounds.

5A.) Tilt the column portion of the drum at a slight downward angle and turn the spindle clockwise just slightly. Remove the last two rounds.
5B.) Keep the drum tilted downwards, and rotate the spindle so that the follower is returned to the beginning of the spiral track (as in step 1).
5C.) Insert two rounds in the top section and release the spindle. Complete loading the magazine by dropping cartridges into the remaining slots.
WARNING: THE ABOVE PROCEDURES SHOULD ONLY BE USED WHEN LOADING THE MAGAZINE TO
ITS FULL CAPACITY OF 73 OR 75 ROUNDS. IF THE USER INTENDS TO LOAD ONLY A PARTIAL
MAGAZINE, THEN THE MAGAZINE FOLLOWER MUST BE DIRECTLY BEHIND THE LAST CARTRIDGE. IF
THERE IS A GAP BETWEEN THE LAST CARTRIDGE AND THE MAGAZINE FOLLOWER, THE DRUM MAY
BE DAMAGED DURING FIRING.

6.) With the drum fully loaded, close the rear cover and secure with both latches. Wind the mainspring with the key located on the rear cover. Wind the key seven (7) revolutions (360 degrees). If the magazine is loaded to only thirty (30) rounds, then the tension should be reduced to five (5) revolutions. DO NOT EXCEED THE RECOMMENDED NUMBER OF REVOLUTIONS AS THIS WILL CAUSE UNDUE WEAR OR BREAKAGE TO THE MAINSPRING.
With step six completed, the magazine is ready to use.
DURING PROLONGED PERIODS OF STORAGE:
Open the rear cover and depress the spring loaded button at the center of the drum. Do not tilt the drum, as the cartridges might fall out. Close and latch the back cover and re-tension the spring three (3) clicks. The drum magazine can be stored in this manner indefinitely.
TO UNLOAD THE MAGAZINE:
Open the rear cover and depress the spring loaded button at the center of the drum. Dump the cartridges out. The rounds in the column will need to be removed individually.
MAINTENANCE OF THE MAGAZINE:
Periodically, the magazine should be cleaned with solvent to prevent the build-up of unburned powder and grit in the spiral track. A significant amount of residue in the track may hinder the functioning of the drum.
To disassemble the drum magazine, open the real cover and depress the spring loaded button. Turn the spring tensioning key COUNTER-CLOCKWISE and remove it. Next, lift the spindle out of the magazine. DO NOT DISASSEMBLE THE MAGAZINE ANY FURTHER.

 

Here is the other picture

Looks like some positions are missing boolits! You need boolits to push the other boolits.

If there is a gap in the feed you will not raise the cartridges properly for the carrier to chamber the round.

 

Oh no I loaded it up all the way that picture was taken after I shot it. That was one of the procedures you told me to do. Shoot it until it jams and then take a picture.

 

Oh no I loaded it up all the way that picture was taken after I shot it. That was one of the procedures you told me to do. Shoot it until it jams and then take a picture.

Wow.... I wouldn't have expected to see it look like that.....I expected to see the rounds more properly aligned in an even spiral, fed outwards as the follower .. eh follows.

Maybe I need some time to think about it and do a little studying.