Promag 12 round drum spring problem

[z-mashin 1]

I hope someone can help out with a problem I am having with a brand new promag 12 round drum I just purchased.

When I first loaded It it was pretty stiff(a lot more effort than MD20) getting the dummy round to start moving downward into mag to load it. I had to push on it w/finger to start it then push with first round. So I took it out and it worked really well until I went to reload it after a drum dump.While I was loading it the spring unloaded itself inside mag. So I took it apart and I noticed that the spring was set in the mag so tension was going against coil wraps of spring. I don't think this is correct. If anyone has any experience with this issue I would greatly appreciate some help before I send it back as a defect. I really like the mag and would like to keep it. EDIT: I may have gotten spring rotation issue wrong I am used to my MD20, so shells in promag 12 rounder rotate opposite. That aside it still unwound itself twice while reloading it.

Edited July 25, 2013 by z-mashin

[Tekilla 13]

I just for 3 20rd drums I took them all apart to inspect them. Did you check if the two post in the spring are straight or if there is any damage to the holes that they go into. If they are unwinding on you the only thing I can think of from the design would be either you have damage to the vertical part of the springs or the holes they go in to or your back plate is not seated firmly. I guess another option might be that you are over tightening the spring and it is popping out of the hole under the tension and recoil. Mines are rotated two and a half turns.

[z-mashin 1]

I just for 3 20rd drums I took them all apart to inspect them. Did you check if the two post in the spring are straight or if there is any damage to the holes that they go into. If they are unwinding on you the only thing I can think of from the design would be either you have damage to the vertical part of the springs or the holes they go in to or your back plate is not seated firmly. I guess another option might be that you are over tightening the spring and it is popping out of the hole under the tension and recoil. Mines are rotated two and a half turns.

I notice that this problem occurs after shooting and then going to reload. So I believe that under recoil(shooting) that spring is moving or compressing enough to start to come out of the hole in gear that it goes into(could be some tolerances are off on base or cover). But it is unwinding upon reloading mag. Everything seems to be in normal condition(spring, gear, and holes for spring mount. I reset spring to 2 revolutions(i will test this setting later). Then decide to send it back or keep it. I think by the hard start to reload it was a little tighter from factory. But since it unwound itself in mag I can only get close. It should be noted that magazine functions well during firing.

[z-mashin 1]

So I took this drum out to test again after resetting spring tension to 2 turns. The drum worked really well during firing but spring unwound itself again during reloads. I also tried a couple of other tension setting with same results. Its going back to seller tomorrow for exchange. Here are some pics. of mag components. You can see the scraping on the drum housing caused by spring unwinding.

[DonL 1]

So it looks like to re-assemble, the spring goes into the main body first, then the shell shuttle, then the back cover. How bad is the retaining hole in the main body? I somewhat find it hard to believe that the spring leg jumps out of its hole upon recoil...They look to be almost 1/2" in length. Can you take a picture of the spring as it sits in the main housing? You could try filling the hole in the main body with silicone, install spring and let it dry. This may be enough to retain it...Or you would get some ShoeGoo and glue the spring leg into the hole of the main body....Put a little water on the applicator...ShoeGoo is sticky and it's easier to apply if you do that. ShoeGoo is a stickier than silicone, but you can still remove it if needed...though that's harder to do with the Goo.....Damn, just read you're sending it back....Let us know how the new one works.

[z-mashin 1]

I know that it seems that the spring would not have enough room to slip those ends out of the mag. body and or gear but it definitely did it. But only after firing and then slipping out during reloading of drum(a few rounds in then unwound spring). I tried a couple of different tensions as well with same results. So I sent it back for an exchange. I will post again when I get new drum and test it. I will also take new drum apart and log spring tension and spring location on gear and body of drum. You can also see in the pic of the drum body the pin location for spring.

[z-mashin 1]

I received a new drum a couple of days ago, and took it out today for a test drive. I tested the drum with some federal multi-purpose loads(which have miraculously appeared in my neighborhood box store as of late). Winchester "universal" as well. I guess they don't want hunters shopping elsewhere during pre-hunting season. Seems almost choreographed. So, the drum dumps went so smooth I will probably pay somewhere else down the line HaHa. I am very happy with this mag. I have to admit a little disappointment when the first one didn't work right the first time. So here are a few pics. of the new mags gear and spring pin settings. I hope this helps out. Follower indexed at about 6 o'clock, and 1 and 1/2 turns spring tension(YMMV).

[gunfun 3,931]

Can you tell what's different between the two?

[z-mashin 1]

I think that there was a little more pressure required to seat the cover into its clips(possibly preventing gear from moving fore and aft). That is about the only thing I noticed different. The fit into magwell was the same(no filing,tight fit fore and aft,some side to side slop). Also spring tension seemed a little lighter on new drum. Without knowing what tension was on defective one, hard to tell. I am just glad the new one works as well as most users report. It sucks doing the homework to find something that should work well and then doesn't. MD 20 still working perfect.

[gunfun 3,931]

Thanks for the info.

 

Perhaps the front of the drum was dished out slightly. It would be interesting to do a careful side by side.