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FTF at upper Chamber lip/step.


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I'm getting a FTF as seen in the first picture below (happens usually on the first or second shell in the mag). The second picture shows the view from the magwell (hang up area circled). And the thrid picture shows how it looks when the factor 5 round mag is loaded with all 5 shells in it.

I have good gassing of ports and mechanics of the bolt operation along with the CSS kit with puk and spring.  I also have the md arms 5 setting plug.  I could run Federal bulk through this without any issues for the longest time (hundreds of shells).  It was until I installed the Tac 47 magwell (which I don't think is the problem itself, as it aligns evenly. The mags sit flush in the well as they did without the extended magwell (meaning the magazine ribs evenly against the bottom of the original gun well.

Please read below above the picture descriptions, any ideas on what is causing it and what I could do to possibly fix it? 

 

 

This shows where the shell nose (front) is hanging up at the upper chamber lip/step. 

hutt.jpg

 

 

This picture depicts what I think may be causing the shells to hang up, but no modifications or filing was done to that are where the lip of the shell sits when chambered.  The front of the shell seems to hit there. I'm suspecting the feed angle and/or pressure of the below shells are causing the loading shell to press up just enough and hang.  Also, what is that area circled in red exactly called where the shell lip sits against when chambered?

b609.jpg

 

 

This is showing with the factory 5 round mag fully loaded with 2 3/4 shells. Notice it fits within the barrel hood at the upper left of the shell, so it doesn't hang up there as others had issues in the past.

95g6.jpg

Edited by rpav99
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What I think is happening is that the feed angle of the first round is too acute.  Your follower is tilting a bit too much.  As more rounds get loaded into the mag, the angle of the follower has less effect, that is why you are seeing it on only the first or second round. My guess is also that you didn't see this problem before is that the new magwell is holding the mag at a slightly different angle.   The fix is as follows-- Order some UHMW polytheylene strip 1" wide x 0.032" thick from Mc Master-Carr -- it's only $0.85 per foot so shipping will cost more than  the actual  stuff.   Or PM me and I'll mail you enough to do a few mags.     Attach to the front of the follower as seen in the photo.   Be sure that the follower slides freely down the whole length of the magazine.  Sand the polyethylene as necessary to thin it down to be sure the follower slides freely.  If you sand it, polish it with some very fine sandpaper e.g. 500 or 1000 grit to make it slide smoothly. 

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Thank you for the suggestion and offering.  I do have some nylon drawer tape in several sizes (anti friction nylon tape used for furniture drawers).  I put it on the factory 5 rd mag and it seems to slide easier on putting in the last rounds.  However, I don't think the feeder angle is off  from normal.  The mags seem to sit parallel and flush like they would have without the extended magwell.  I also have several 10 round SGM mags that worked flawlessly and same thing happens. The SGM mags slide smoothly.  Actually it can hang randomly on any round even last.  By manually cycling it in slow motion, I can get it to hang every round.  Of course when the gun is firing, the bolt is functioning much faster, and most shells will be put into the chamber, if even by slight force.  However, like I mentioned, it will hang sometimes when firing which I want to prevent.  

 

Now I'm curious, I may even take off the magwell to test with some unmodified 10 round SGM mags I have and see if the original rock and lock way will replicate the issue.  

 

Now my last question, and I say this will due diligence and common sense, would it be at all safe to slightly, and I mean slightly chamfer that area on the top (circled in red on my second picture in original post)?  Would the shell lip not sit correctly when chambered?

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Malcolm is correct about the exaggerated forward tilt of the top rounds in the mag causing those shells to dive more than the rest. Common problem with single stacking rimmed cartridges... each one adds forward tilt. I've also used shimming the front of the follower to fix this prob on +2 rd mag extension FPs. Something else I do to all my custom builds is to remove the sharp edges from the front of the feed ramp area and re-profiling / polishing that area for a much smoother feed. It will most likely cure your problem there.

 

 Do NOT mess with the areas outlined in blue. The RED part is what needs a little work, and not much. I am not responsible for any damage someone does to their Saiga from attempting this mod. Don't anyone get anywhere near their Saiga with power tools without realizing ahead of time you are doing that at your own risk.

 

post-1293-0-70645200-1380334405_thumb.jpg

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I have done that mod right when I got the gun and worked wonderfully.  The area I'm talking about is the opposite side and my shells have the front of the shells upward.  It would catch on the top portion of the barrel chamber lip area.  I worked on it a little and now working much better.

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Didn't look that close before at the pics, but that notch definitely isn't normal and could cause feeding probs. Looks like someone got a bit carried away with modifying there. I was just noticing the extractor notch also looks like it's had a bit much filing done it also. Don't get any deeper there or you may end up with a dangerous situation.

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That notch was like that when I got the gun brand new from Mississippi Arms.  It is the IZ-109 model.  However, I never had an issue with a shell hanging up there.  I think I remember a few on this board with pictures of not even having that notch there at all (like being cut off), which caused the shell to angle up too much sometimes and hang up.

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Didn't look that close before at the pics, but that notch definitely isn't normal and could cause feeding probs. Looks like someone got a bit carried away with modifying there. I was just noticing the extractor notch also looks like it's had a bit much filing done it also. Don't get any deeper there or you may end up with a dangerous situation.

 

That notch is standard factory now.  My Century Arms has it as well.  Mine is a 2011.  I really hate the way they cut it out, as they damn near undercut it off!  I remember something about that the notch is supposed to allow 3" shells better clearance when ejecting. 

 

Edit: Nevermind!

Edited by Capt Nemo
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I've seen the same failure with mine, and it's a variation of the extractor problem.  The shell comes out of the mag nose high and catches under the extractor and is also held at an angle by the stripper/feed foot.  In this case, the shell rim is touching the bolt face, which gives a real high angle.  The extractor spring won't give enough to let the shell straighten out.  This one is a hard jam.

 

If the shell gets caught under the tip of the extractor and on the feed foot, but not touching the bolt face, it will be held at a lower angle, but will still hang things up.  I see this one the most with mine.  This one is a soft jam, as it will clear with a hit to the charging handle.

 

In both, tunning the extractor spring is needed.  It only needs to give a little bit to straighten out the shell. 

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