Problem with my MD Arms 20 round drum.......

[Rolex John 2]

I'm debating on whether to return this to vendor I purchased it from...heavily leaning toward returning it.

 

I took my drum out to the range yesterday to test it - loaded it fully with 2 3/4" slugs. The first 10 rounds had a failure to feed after firing each round - in each instance the bolt would hang open. I'd yank on the handle, release it, bolt would close. I'd fire another shot and the cycle would repeat. After about the 10th round, the drum/gun began firing and functioning properly.

 

I went to reload the drum, and could not get more than 1 round in. The drum would not turn to allow the next round to be loaded.

 

Can anyone diagnose these issues or is just a faulty drum that needs to be returned?

[evlblkwpnz 3,418]

Faulty, I'll give you $50 for it.

[Rolex John 2]

Faulty, I'll give you $50 for it.

 

I'm guessing your response is playfully sarcastic and that the drum can easily be fixed? The vendor suggesting I adjust I dissemble the drum and adjust the spring tension. I reviewed disassembly in the manual and got to the part where you remove the follower and got stuck (I'm not exactly what one would call mechanically inclined).

 

Would adjusting the spring tension help what ails my drum? Is there better/more detailed disassemly tutorials out there than what's provided in the manual?

[gunfun 3,931]

It sounds like you might need to use the next gas setting lower with that ammo.

 

Also, it sounds like the second time around you were not pushing the round fully to the rear. EVL is trying to take advantage of you, because he knows good and well I'd give you $52 for it.

[ec4321 113]

58 bucks.

[Rolex John 2]

It sounds like you might need to use the next gas setting lower with that ammo.

 

 

Can you elaborate on this? The ammo is well tested using my 10 round magazines with no problems. I'm not understanding how the gas setting should be different for the drum.

Edited November 26, 2012 by Rolex John

[rnemhrd 165]

The drum has more spring tension when full. This puts mure prussure on the botton of the bolt and bolt carrier causing more drag on them. Giving the gun more gas will let the bolt carrier get to the back of the gun with the increases friction caused by the drum. As you empty the drum the spring pressure is decreaced and thats why it starts to function. Stick mags have less spring pressure also. You could also lighten the spring in the drum up. I do not have a drum so can't I help there. If I did'nt live in NY I would offer $60. Just need tuning is all.

Edited November 26, 2012 by rnemhrd

[gunfun 3,931]

your drum pushes the shell up harder than stick mags and causes more drag against the bolt. Thus if your gun is weakly running the ammo with the stick mags, it will fail with the drum. This could be a good indicator for basic gas work with light ammo. borderline guns will run weaker ammo with the stick but not the drum. That ammo may be right on the border between settings, which would mean switch to the next setting. Simple rule: if it doesn't run on #1, then switch to #1 with no harm.

 

Drums also cycle slower than stick mags so if your bolt is not reaching the full rear position of it's stroke, it may not give enough time for the shell to pop up in time.

[sunnybean 939]

He's saying the drum has more spring tension than you stick mags creating more friction. You might need to decrease the spring tension a bit. Also, my drums seemed to run better once they were used for a bit. All those new parts needed to rub each other down a bit. Not sure what might be causing yours to jam up internally though.

[Rolex John 2]

I'd very much like to adjust the spring tension on the drum. Is there a drum dissasembly tutorial anywhere? As I said, I've reached a sticking point.

[olsn500 4]

i think if you search the forum and follow the links there are some tutorials or at least drum videos to check out that might help. i typed "drum disassembly" and got some good stuff

[evlblkwpnz 3,418]

If you decrease the spring tension, the drum will not keep up during rapid shot strings and could potentially not keep up with the action during slow fire (may be unable to push the next round up before the bolt passes it during the forward half of the cycle). They are supposed the come from MD Arms with 3 turns of tension, which I have found is indeed perfect. With drums, not only do they have more spring tension, but they introduce more friction from more rounds moving in the device, much like the comparison of a 5 round mag vs a 10 round mag. From afar, it is difficult to say exactly what is wrong, but I can all but guarantee it is not the drum.

 

Put the drum back together. Try the same ammo in the drum on a less restrictive gas setting (2 for a factory regulator). If that doesn't yield satisfactory results, the weapon needs work.

 

I recommend a combination of friction reduction and some degree of attention to the gas system. How much gas work depends on what your desired baseline ammo is and how many rounds you would like to fire in short order before having failures. If you shoot like a sane person (read: not like me), you could probably get away with friction reduction and adding a 4th port at factory size. If you want to raise all out hell and fire 100s of rounds of Winchester Universal in a few minutes (like me), you will likely need more than 4 ports at factory size or 4 ports larger than factory. All things have to be nearly perfect to get what I call "insane reliability", especially the friction reduction, or you have to go large on the amount of port surface area. I have seen people do things that place an additional burden on the gas system to make up for the good idea that was actually bad. To what limit would you like to take the weapon? Red pill.... Blue pill....

 

 

I was joking about the $50. I'd give you $60 for it and you could just run stick mags and be happy with the weapon as-is and forget about that lowly unreliable drum ....then I would post some video of that drum in an insane Winchester Universal dump video of a rotation of 300 rounds worth of MD-20s. Flawless? Maybe not, but damn close.

 

I'd very much like to adjust the spring tension on the drum. Is there a drum dissasembly tutorial anywhere? As I said, I've reached a sticking point.

I have tried it. Trust me.... don't do it. It can cause feeding problems.

[G O B 3,516]

Spray the insider of the drum with silicone dry lube. Use better ammo!

[gunfun 3,931]

Speaking of which, look here for a growing list of what is known to run well: http://forum.saiga-12.com/index.php?/topic/46189-md20-ammo-table-guide-pdf-attached/page__st__60#entry821387

 

I linked to my post with links to the most up-to-date info. Credit should go to the OP of that thread.

[Squishy 1,149]

Spray the insider of the drum with silicone dry lube. Use better ammo!

 

What is the best dry lube? I don't assume they're all the same.

[Squishy 1,149]

What is the best dry lube? I don't assume they're all the same.

 

And they certainly aren't. I obtained some Hoppe's Dri-Lube which doesn't contain silicone "to attract dirt" and you don't want to be using this stuff on anything other than metal mags with metal parts. Some of the key components are Acetone and Toulene...need I say more?

 

Know of a plastic/polymer safe dry lube?

[evlblkwpnz 3,418]

None of the 13 MD-20s I still own have been lubed beyond what was done at the factory, aside from 5 of them that I used during a Thunderstorm. I was pouring rain out of them before and after they were loaded. Those were taken apart, dried, and received a touch of the graphite that comes with the BetaMags. If they get dirt in them, I shake it out and keep on blasting. They are not nearly as sensitive to debris or lack of lubricant as people seem to think. Raise hell with it.

Edited November 29, 2012 by evlblkwpnz

[Squishy 1,149]

I took the opportunity to ask the question in this thread but it doesn't not necessarily depend on whether or not dry lubing MD20 drums is a good idea. I am still interested in learning the answer to the question. Mag Slick says it is ok for plastics but often there are off the shelf products that are virtually the same as the special purpose stuff.

[evlblkwpnz 3,418]

I wonder what MD Arms uses on them originally? Whatever it is, they use it sparingly.

[zenman223 460]

I took the opportunity to ask the question in this thread but it doesn't not necessarily depend on whether or not dry lubing MD20 drums is a good idea. I am still interested in learning the answer to the question. Mag Slick says it is ok for plastics but often there are off the shelf products that are virtually the same as the special purpose stuff.

Never used any dry lube on anything but I wonder if KIWI Camp Dry wouldnt work on plastics as an off the shelf alternative. It IS silicone but it drys completely so it shouldn't attract dirt. Just a thought.

[Squishy 1,149]

Never used any dry lube on anything but I wonder if KIWI Camp Dry wouldnt work on plastics as an off the shelf alternative. It IS silicone but it drys completely so it shouldn't attract dirt. Just a thought.

 

big-J, I've been doing research on this today on the web in general and a number of gun boards and it occurs to me that I have never researched a subject where the opinions and anecdotal information represents such a wide range as to what people like and recommend. All the way from "use nothing, just run it clean and dry" to "after using <insert name brand here> my gun feeds flawlessly". If you're looking for an overwhelming favorite you won't find it.

 

Of course what would work well for metal on metal interactions on/in the gun are one thing, polymer or even metal magazines is another. And you can find some products that have multiple mentions but it seems there is a wide range of products that get high marks such as "I've been using this stuff for 40 years and I wouldn't think of using anything else."

 

I was going to start a thread about this here but I'm sure it would be more of the same, a wide range of very strong opinions that wouldn't serve to help reach a conclusion.

 

So it seems to me the only thing to do is find the best two or three and try them out.

[jdpete 6]

I recently purchased a MD20 drum and can't get it to cycle. It FTE after each shot. I have a 4 port gun that has the ports opened to factory specs and none are blocked. It fires all my 10 round clips just fine. I am using Walmart Federal bulk ammo 7 1/2 shot. I am using a tac47 auto plug and even bottomed it out without any success. Any suggestions?

[misterT 174]

My MD20 drum worked flawlessly right out of the box after fitting it to the gun of course, now I have not put a lot of rounds through it yet. But I do have a well profiled and polished FCG and I polished the bolt and carrier, first on a scotchbrite deburring wheel then with brown triple compund on a buffing wheel. Now they dont look like Paulys glass bolt but they are very smooth. I also sanded the rails in the receiver with 600 grit to remove small burrs and rough spots and the mating grooves in the bolt carrier. interestingly enough I did have a couple of FTFs with my new 12 rounds stick mags!

Edited January 5, 2013 by misterT

[DNR 20]

jdpete if might need fitting - even the instructions inclued with the drum tell you that you might have to shave some plastic off the section that will fit in the rear part of the mag well. Since your saiga 12 cycles ammo in all other means - it sounds like the drum is not fitted and not feeding the shells correctly, tweak it a bit.

[jdpete 6]

The drum snaps into place fine. I'm afraid if I tweak it it may not stay as firmly in place. I thought the tweaking was only done when the drum would not snap into place?

[sapper1371usmc 107]

The drum snaps into place fine. I'm afraid if I tweak it it may not stay as firmly in place. I thought the tweaking was only done when the drum would not snap into place?

Exactly. The only fitting that needs to be done is to be able to insert the drum into the weapon and have it locked in place. Depending on the type of malfunctions you are having, try increasing or decreasing the spring rate inside the drum to see if that solves the problem.

[jdpete 6]

I recently purchased a MD20 drum and can't get it to cycle. It FTE after each shot. I have a 4 port gun that has the ports opened to factory specs and none are blocked. It fires all my 10 round clips just fine. I am using Walmart Federal bulk ammo 7 1/2 shot. I am using a tac47 auto plug and even bottomed it out without any success. Any suggestions?

 

Tried decreasing the spring tension in the drum to 2 1/2 turns but still got FTE. Little frustrating. The bolt is polished a little. I wonder if it is possible that I have some slight binding from the gas rod from when I put the gas block back on after port work. I can push on the gas plug with my finger and move the plunger relatively easy but maybe it should be even easier I don't know. Has anyone ever tested how much pressure is required to push the plunger rod?

[rs51085 136]

One thing i haven't seen mentioned yet is weather or not the shells you are using are compatible with the md 20 drum. it works with 2 3/4 inch shells only. Also some brands/types of 2 3/4 inch shells won't work with it if they are still to long due to crimp styles. I think the md 20 has problems with roll crimps? you need to check the ammo compatibility chart and see if the ammo you are using does work with the md 20.

[jdpete 6]

I looked at the MD20 ammo chart here and it says it should cycle the federal 7 1/2.

[evlblkwpnz 3,418]

I recently purchased a MD20 drum and can't get it to cycle. It FTE after each shot. I have a 4 port gun that has the ports opened to factory specs and none are blocked. It fires all my 10 round clips just fine. I am using Walmart Federal bulk ammo 7 1/2 shot. I am using a tac47 auto plug and even bottomed it out without any success. Any suggestions?

If it is feeding, the drum (feeding device) is doing its job. Try it with the factory gas regulator and factory puck. The weapon will likely need some very focused and detailed work. If it was easy to make these weapons run low base loads in MD-20s, everyone would have 100 and 200 round MD-20/bulk birdshot videos posted on youtube

 

Outside of fitting, I do not fiddle with the drums that I use. My weapons get a lot of time and effort thrown at them to make them what they are. Never give up....