Drum/Gun Issue

[Monk 0]

Took out the drum today. Fired flawlessly through one Saiga - did about 5 drum dumps.

 

Tried it in another Saiga, and it had problems if there were more than 8 or so rounds in the drum. This gun was running perfectly fine with AGP mags. There were two different places it would catch:

1. Where the little foot that picks up the next round meets the top round. To clear this, I had to manually force the bolt forward.

2. Just before the bolt rotates and locks. Trying to push it forward the rest of the way manually would not work - had to back up the bolt and try to chamber it again.

It did this frequently for three different drum dumps, and all them had in common the fact that the drum was more than half loaded.

 

I was firing Federal walmart bulk stuff. The spring was set on the default setting (I think 3 turns?), as I have not messed with the spring tension at all since I got it.

 

So what are some possible causes and solutions for this? I was thinking that perhaps there was excess stress on the bottom of the bolt and bolt carrier, and the problem never occured before with AGP mags because they don't have the capacity and tension that a 20rd magazine would. Would reducing the spring tension help? If spring tension is the issue, why would it occur a lot with one gun and not at all with another gun? Just differences in the internals that make one drag?

 

I was planning to smooth and polish the bottom of my bolt and bolt carrier, but I have absolutely no experience with doing this and I am afraid of messing up irreplaceable parts.

[MikeD 541]

Monk, This might be a couple different things. It could be that your one gun runs smoother and less energy if being robbed as the bolt passes the next shell and over the hammer (twice), ejects the round..... It maybe that a slight polishing of a few rubbing surfaces would clean it up. It also could be that the recoil springs in the one gun aren't as strong as the other. It sounds like it is picking the next round up fine but just doesn't have the energy to close up all the way afterwards. I have found that the factory recoil springs can be all over in the actual lbs. of force they apply. They average 15 to 16 lbs. But could be a few lbs. under this each.

 

You can try a few things to verify. First swap the operating rods from the one gun to the other and see if anything is different in which gun wants to operate. You can also swap the bolt and bolt carrier to see if the problem follows those parts to the different gun.

 

It probably would help to reduce the spring tension on the drum. It wouldn't require as much energy to pass and then strip the next round. The drums will operate low brass at 2 revs (empty) but come on 3 revs (empty). But since the one gun does fine with the drum as is you should probably try to identify the solution in the gun itself. There is probably a very simple fix to this. Probably free too with a little polishing. I would think at most you might need to buy a stronger recoil spring which would be around $10.

 

Please let me know what you do here and your results.

[MikeD 541]

Also on the polishing. As long as polishing the rubbing surfaces on the bolt, bolt carrier and hammer is all you do you don't have much of a chance of messing anything up. Polishing is barely going to remove any material and will just smooth the surface and reduce friction and help remove imperfections in the metal that can cause drag and extra friction.

[Monk 0]

I didn't even think about swapping the internals. That should narrow it down a lot.

 

One concern I had though, is with the new spring you are going to send out. Since this new spring will cycle more ammunition reliably, will it have a stronger tension than the current spring? I don't know much about springs at all, especially with the whole high brass low brass thing, but I would assume that stronger springs equals better feeding?

[MikeD 541]

I didn't even think about swapping the internals. That should narrow it down a lot.

 

One concern I had though, is with the new spring you are going to send out. Since this new spring will cycle more ammunition reliably, will it have a stronger tension than the current spring? I don't know much about springs at all, especially with the whole high brass low brass thing, but I would assume that stronger springs equals better feeding?

I actually have a better fix now. I'll be releasing the updated info very soon. The stronger spring did do the trick but it did cause some drag issues with some guns. My new solution is way better!!!