Bullet guide related FTF?

[pjj342 632]

My rifle is a 2002 iz132 with a round trunnion and a dinzag bullet guide.  I also replaced the mag catch and there is nearly zero front/ back wobble (eliminating it from suspicion) Ive noticed lately that I get random FTFs with FMJ cartridges.  Ive known for a long time, that my rifle 'prefers' HPs, as Ive never had a malfunction with one.  So, I only shot HPs.  Until recently that is, I got great deal on a case of tula 122gr fmjs so I started shooting them again. 

 

The malfunctions I get are always the same.  The bullet gets tilted into the chamber, and the bottom of the case gets stuck under the bolt.  Its the same when I dont make a mindful effort to 'let it fly, hard' when I load the first round.  Mind you, this does not happen with HPs, ever.

 

So I took a look at the chamber clearance when a cartridge loads.  Sure enough, the tips of the bullets are barely making it over bottom of the chamber mouth.  

 

Here are my questions:

 

How much clearance should I be getting?  Are the tips supposed to be smack dab in the center of the chamber, higher, lower?  

 

Is this common for converted saigas?

 

Any ideas on a fix?  Ive thought about shimming it by putting sheet metal underneath, to raise it up, since I cant bring it out closer to the mag.

 

thanks guys

 

 

 

 

[imarangemaster 315]

I think a very thin sheet metal shim might do it.  It sounds like the bullets are entering too low, then kicking up when they hit the chamber. Something like the thin aluminum in duct work.

[Spacehog 2,218]

Boom,

Do you have any pics of the FTF? I find it odd that the bottom of the casing ends up under the bolt when the bullet is barely clearing the bottom of the chamber. I would have expected the opposite...too steep of a feed angle with the tip hitting the top of the chamber.

 

One thing I would due is check the feed angle of the HP and compare it with the FMJ. Also compare the bullet olgive on both rounds. It there is a big difference in length or shape, that might point you in which way you need to go with the feed angle.

 

From your description, I would think you will end up needing to either extend or shorten the length of the bullet guide.

[thebuns1 4,323]

Swapping the catch should have helped if the mags were not seating properly, but to completely rule it out, try pulling back on the mag towards your body and try to charge the rounds that way. That will help you narrow down your issues.

 

Is the top of the bolt resting around midway up the casing? Is the nose of the bullet making contact with the top of the chamber?

 

Ive also read that selector stop plates can cause issues, but havent ever experienced it.

[pjj342 632]

I think a very thin sheet metal shim might do it.  It sounds like the bullets are entering too low, then kicking up when they hit the chamber. Something like the thin aluminum in duct work.

I already have a piece installed and for now, it seems better.  Ill have to get to the range and see if it makes any difference.  

 

Boom,

Do you have any pics of the FTF? I find it odd that the bottom of the casing ends up under the bolt when the bullet is barely clearing the bottom of the chamber. I would have expected the opposite...too steep of a feed angle with the tip hitting the top of the chamber.

 

One thing I would due is check the feed angle of the HP and compare it with the FMJ. Also compare the bullet olgive on both rounds. It there is a big difference in length or shape, that might point you in which way you need to go with the feed angle.

 

From your description, I would think you will end up needing to either extend or shorten the length of the bullet guide.

If it happens again, Ill be sure to take a pic.  After really looking at my rifle and how it feeds, it seems almost impossible for the tip of the bullet to be in the chamber with the case head under the bolt, pushed down into the mag.  

 

Im tinkering with the idea of making the bullet guide higher, but shorter.  This particular malfunction could not happen if the feed angle was less acute, I think.  It seems the farther out the bullet guide is, the steeper the angle.  And the closer to the chamber it is, the shallower the angle.  I seem to think shallow would be better.

 

Another little piece of info.  This rifle has always mangled soft tip bullets.  Probably because of the bullet tip getting gouged at the chamber mouth, while feeding.

 

Swapping the catch should have helped if the mags were not seating properly, but to completely rule it out, try pulling back on the mag towards your body and try to charge the rounds that way. That will help you narrow down your issues.

 

Is the top of the bolt resting around midway up the casing? Is the nose of the bullet making contact with the top of the chamber?

 

Ive also read that selector stop plates can cause issues, but havent ever experienced it.

When I did my magazine part of my conversion, I took too much off my factory saiga catch.  So i used a normal ak catch and it works very well (after 6hrs of fitting and spring tension fighting, pain in the ass).

 Ill make it a point to pull the mag back and see if it effects anything.  I could see, with such a small margin of error (in my rifle that is), where a tiny tilt could really cause problems.

 

Is the top of the bolt resting around midway up the casing? Is the nose of the bullet making contact with the top of the chamber?  

Yes and yes.  The case head is either still in the mag, or has been pushed back down in.  The nose is jammed into the top of the chamber, to the point that it makes my seated bullet crooked in the case neck.

 

I know my selector stop plate is factory.  Though, I could see how an aftermarket one might mess up the angle of the magazine.

Edited August 29, 2014 by Boomsick42

[Gzus Kryst 53]

Not a fix but might help isolate the issue, if you think the BG is wrong/off load up the stock mag and hand cycle see if it jams the raised portion of the mag should bypass the BG and any issues it may be causing

[pjj342 632]

Not a fix but might help isolate the issue, if you think the BG is wrong/off load up the stock mag and hand cycle see if it jams the raised portion of the mag should bypass the BG and any issues it may be causing

Oh man, makes me kinda wish I had kept one.  Sold them a long time ago.

[SaigaFL 4]

Century fixed my FTF issue on my new 5.45 Saiga by chamfering the chamber entrance and filing the mag catch.

 

 

[G O B 3,516]

Another odd failure to feed can be the front of the mag is sitting too high due to that part of the sheet metal receiver being bent. I know I never dropped the gun on the mag, but the front of the mag opening was bent up maybe 1/32", a big flat punch and a whack with a BFH (Big Fucking Hammer) put it back to right.

[Spacehog 2,218]

 

Not a fix but might help isolate the issue, if you think the BG is wrong/off load up the stock mag and hand cycle see if it jams the raised portion of the mag should bypass the BG and any issues it may be causing

 

Oh man, makes me kinda wish I had kept one.  Sold them a long time ago.

Pm me your address and I send you one if you want to check. I'll pay shipping there if you will ship it back when done with it.

[Spacehog 2,218]

Boom,

Don't know if this will help you or not, but at least it will give you a point of reference when doing your data collection. In the pic below the bullet guide extends out past the round trunnion 2.8 mm. It is identical in my other x39 also with a round trunnion.