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Drum reassembly question


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So I tested the drum the other day-flawless with high brass but multiple FTE's with Federal bulk pack. The gun runs fine with the stock mag and 8 round Surefire. I reduced the spring tension down to two revs and it hand cycles everything fine. I haven't had a chance to fire it yet, though (it will probably work perfectly is my gut feeling). My question is whether I reinstalled the follower correctly. Does the hollowed out side face the feed scoop? That's the way I did it and it went together fine. The user's guide is sort of unclear on this and I don't want to screw anything up firing the gun if it's wrong. Thanks for any help.

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So I tested the drum the other day-flawless with high brass but multiple FTE's with Federal bulk pack. The gun runs fine with the stock mag and 8 round Surefire. I reduced the spring tension down to two revs and it hand cycles everything fine. I haven't had a chance to fire it yet, though (it will probably work perfectly is my gut feeling). My question is whether I reinstalled the follower correctly. Does the hollowed out side face the feed scoop? That's the way I did it and it went together fine. The user's guide is sort of unclear on this and I don't want to screw anything up firing the gun if it's wrong. Thanks for any help.

Schmeopleoticus

, Our members here have confirmed the correct way to reinstall the dummy round. But.... You really shouldn't have to turn the spring tension down for low brass if your gun is running smoothly. I NEVER turn the spring down in the drums I use. The factory setting of 3 revs (empty) is required for most high brass ammo. I am betting that with some very slight and easy tweaks you won't have to either. It is a nice option to have for someone that doesn't feel comfortable tweaking their gun. But all these tweaks are very easy... If you can clip your finger nails with out drawing blood you can probably perform them yourself with a little close reading on the tweaks. Here is an email exchange between me and a customer that is having fte problem with there drum and low brass. It should be an interesting and encouraging read...

 

Him:

-------- Original Message --------

Subject: Drum and FTE

From: "Max" <>

Date: Wed, February 10, 2010 4:30 pm

To: <info@mdarms.com>

 

Hi Mike (This is a duplicate of a PM I sent on the Saiga forum),

 

First off I would like to thank you for the price drop for the drum, I most likely would not have been able to afford one this soon otherwise. And also sorry for having to bug you about this issue but....

 

I received my drum the other day, did a little bit of A and B fitting and went out shooting the next day. The drum locks up rock solid with no movement and clicks nicely into place. The problem was lots of failure to eject. The most I got off in a row was 5 rnds and many times it was FTEing every rnd, I did this w/ a 100 rounds of Fed. bulk with no noticeable change. As far as my gun goes it has 4 gas block holes, gunfixer on setting 3, and I would say it is fairly well broken in and has no problems whatsoever with Fedral bulk pack out of my stock Russian 5 rnd mag. It is a little finicky with AGP-10s but I figured it had something to do w/ their mags.

 

So I did as the manual says and lowered the spring tension and went out again today. I started on 2 rotations, still FTE, then I tried 1.5-feeding problems, 2.5 - FTE, 2.25- FTE.

 

So at this point I don't know what to do, I have done a very small amount of polishing on the internals, but like I said before, the factory 5 feeds it all day with no problem. And as your product page says : ' If you can run factory Izhmash mags in your Saiga-12... the MD-20, Saiga-12 20rd drum will work in your shotgun with little or no effort on your part...'

 

I would really like to get your product working, but if I can't, what's the point of having 20 rounds when you keep having stoppages?

 

Please let me know what you think I should do next?

 

Thank you,

-Max

 

Me:

----- Original Message -----

From: info@mdarms.com

To: "Max" <>

Sent: Wednesday, February 10, 2010 6:01:49 PM GMT -07:00 US/Canada Mountain

Subject: RE: Drum and FTE

 

 

Max, Your AGPs are probably fine. With increased capacity is increased drag. Having the same problem after dropping your spring tension in the drum and with AGPs is a clue. If your gun was up to par you would be able to fire low brass, from the hip (held more loosely with more loss of energy), with the drum on the max spring set. Max is factory (3 revs empty). Try polishing first. The bottom of the bolt and bolt carrier and the top of the hammer. This usually does wonders. There is more though you can check if this doesn't fix it. Example... My full-auto 12 ga. I made the big mistake of using a new gun and not testing it's characteristics. You should do that before even a simple pistol grip conversion... When we completed the build and tested it I was getting ftes. Even with high brass! I was stumped because I polished up the major surfaces during the build. I knew I had good ports. I thought it was something to do with the FA conversion. That in someway it was causing it... I went ahead and polished up the rails, and basically every riding surface in the gun. Not one bit of change. Then I did a last resort and shortened the extractor spring. Still no major change. I completely went over and analyzed ever change made for the FA work. Nothing I could see that could cause high brass to eject! I noticed the gun was closing up a little slow. This is nothing new if your gun is FTE. Sometimes a shell might eject but the bolt carrier has lost so much energy doing it and then stripping the next round that that is a common response... Then I analyzed the ejected shell casings. I noticed that the extractor cut out was distorting the hull and swelling out the plastic into a little bulge. It was driving up into the slot. Usually when a gun does this it will hang up obviously in the spot. And not cause fail to ejects... I thought what the hell might as well try the extractor slot fix. I chamfered the edge of the cut out and rounded it over well. Took the gun out and it has run like a scalded dog ever since! The bulged material was causing enough drag while being extracted that it was cause the FTEs like that even with high brass! I never thought that I would see any change after rounding the cut out. Just didn't think it could cause that much drag ejecting, thought all the troubles of the sharp edge was FTFs or slow feeds. But it all paid off. I learned something new and very useful. And I am betting if you suggested such a cause and fix to some of the other saiga gurus you would get the same as I thought, that it was highly unlikely the cause. But it was! And now with all the extra polishing and tweaks trying to figure it out... I can even fire Winchester bulk pack ( about the weakest ammo there is) from the hip, one handed, with a max tension drum, full auto! Here is a video, about half way through it I am doing just that. You can tell the rate of fire has slowed down from the energy lose but it is still ejecting just fine!

Please let me know on your polishing results. And I want you to know that all these saiga tweaks are easy. If your ports are good.. You will be good. All these tweaks will not make up for missing or blocked ports. But there is a warranty service for that if that is the case. You will be able to stack your life on your gun with the drum as well as have a blast with cheap ammo at the range without constantly clearing FTEs! There is really no need to change the spring tension of the drum either. That is just a suggested fix for those to nervous about some very simple tweaks in the gun. I NEVER change the tension in the drums in the guns I use. They need the max for most high brass rounds. Brenekee KO slugs ( not the sabo ones) are the only high brass I know of that will run 100% in an over gassed gun with the drum on 2 revs empty. And that is just crazy that they do. Again, please keep me posted. Some of these guns are a little crude... But I have yet to see one that can't be fixed, and the very most of them very easily. MikeD

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Thanks, man, for the info. I've already polished up the underside of the carrier and the bolt, also the hammer face. This was a very light polish, however. I'll try to get it a little slicker. The gun has three unobstructed ports--two are tucked up out of sight but I can get a paperclip through each one.

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Thanks, man, for the info. I've already polished up the underside of the carrier and the bolt, also the hammer face. This was a very light polish, however. I'll try to get it a little slicker. The gun has three unobstructed ports--two are tucked up out of sight but I can get a paperclip through each one.

 

Those ports are probably just fine. There is a chamfer on the under side of the block that sits against the barrel. While they might appear to be visually blocked... as long as they aren't closed off (outside of that chamfer) they are essentially wide open. The gas is so fluid and violent that the over hang visually blocking the ports is of no real significance in obstructing gas flow. Try polishing a little harder with a cratex tip on a dremel. The job isn't to make the material shiny as much as it is to remove grabby, draggy imperfections in the areas. A mirror polish is not necessary. Be aware of your bolt ration while locking and unlocking. Make sure to smooth chunkiness and sharp grabby corner that twist on the top shell in the mag. If that doesn't solve it we can explore some more easy, non aggressive tweaks.

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^^^ hey that's me up there (Max). Glad our exchange could be used to help someone else out.

 

Schmeopleoticus, your ports sound alot like mine, I've got 4 that I can get a fishhook thru the barrel but they appear slightly blocked by the gas block.

 

I have yet to do my polishing, hopefully tomorrow, then to the range. I really want to post about positive results.

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Mike! I think I found that scalded dog you were talking about. Went shooting today and after dumping all 20 rounds rapid fire, all I could say was (if you excuse my foul language) FUCK YA! I ran through a whole value pack of federal chuckling to myself with a big ass grin on my face. I didn't think that polishing could make such a difference, but it did, almost night and day.

 

I am seriously thinkin about getting another drum! Just want to say thanks to Mike for making such a quality product and offering such personal support to go with it.

 

If you guys have not tried one of Mike's drums, you should, I think it will make you like your gun that much more, that's what it has done for me.

 

Thanks again Mike.

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Mike, thanks so much for your personal attention on this stuff! :super:

 

>>I thought what the hell might as well try the extractor slot fix. I chamfered the edge of the cut out and rounded it over well.

 

For those of us that are more visual..... would you mind snapping a pic of the area that needs work?

 

In my mind I'm picturing that cutout on the carrier rod, but not totally sure if that's it.

Would really help to see the degree of work you did on it too.

 

Thanks!

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I think he means the slot in the top-right of the barrel (inside receiver) where the extractor fits when the bolt/carrier locks/closes. In other words, its in the receiver where the shells go into the barrel.

 

I think this is what Mike is talking about, but I could be wrong.

 

If this doesn't help I'll try to take a picture when I get some more time.

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It didn't go so well. I had multiple FTE's with both Fed and Rem bulk pack ammo. I know it isn't the drum. I have an instinctive feeling that the gun is undergassed. I'm mechanically inclined so I removed the gas block and looked at the ports. They were undersized and, I believe, partially obstructed by the gas block. So I enlarged them to 3/32 and relieved the obstructing metal slightly with a file. I love this gun-the perfect toy for a tinkerer, like me! Will test-fire tomorrow or possibly Monday and report back. If it turns out to be overgassed I'll have the perfect reason to get a Gunfixr plug (I really want one anyway, just to be able to change settings without tools!) See ya.

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Mike, (and anyone else), the gun was undergassed. Opened the ports up to 3/32 and it runs like it should now. The only round that gave me a little trouble was Rem bulk but Fed bulk ran perfectly. Drum also back at three turns on the spring. Thanks for a great product and for the help. We need more like you around!

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