Author Topic: Interesting Feed / Ramp Issue and Receiver Design Observation  (Read 5124 times)

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Offline CitizenPete

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One of the CAI VZ2008 rifles I recently sold (out of state) had a serious feed issue with cases not feeding at all and reportedly the sides being really scratched up.  The rounds where being stripped from the magazine and were stopping mid way up the ramp, halting the carriers forward motion before being able to go into battery.
 

I was shocked since I put all vz.58s in my collection through a fairly extensive testing, modification and upgrade process and I had advertised them as ready to shoot.  The bolt, carrier, ejector, and extractor, headspace, FCG, springs, etc, etc.. were all inspected modified as required, and tested 3 times with 10-30 rounds per test. There was no bolt drag etc. -- all was fixed cycling and and working fine.  I tabbed all carriers, but did not R&R the CAI modified disconnectors in the vz2008 variants.  I shot 60-90 test rounds through all the CAI vz2008s with no issue. Three other vz2008 buyers I had sold to reported back with stellar reviews and zero issues after testing them.  I shot various different manufactured rounds GT, Wolf, Brown Bear, Tulammo, FMJ, HP, SP all with no issue.  So, this problem was bizarre to me -- what was different? -- did I screw something up by removing material from the bottom of the bolt?  It shot fine during tests.



Well I'm not one to sell and run, and I told the buyer that I stood behind the gun and my mods, so if he wanted to transfer the gun back to me (unmodified), I would send him another new vz2008 (I'm keeping one) or we would fix the problem together remotely.  The buyer was not a novice shooter, but his was his first vz.58 variant, and I incorrectly wondered was this was operator error. Was he riding the bolt into battery, in stead of a sling shot release?  Did one the mags I included with the gun have defective follower? -- no -- he tried different mags. Was something wrong with the feed ramp? -- never heard of that. Perhaps the recoil spring was weak?, but I had inspected and tested fired it without issue.


In the end we worked it out, with the buyer providing me with an education on yet another vz.58 receiver design difference, and I thought this might be of interest to other vz2008 owner/operators.  For his trouble and schooling I gladly sent him a full set of NOS springs for one of his (now) favorite new guns.


Here are two pictures showing the problem and resulting marks on the cases:










See the deep groves cut in the side of the brass? See how the brass is apparently wedged in the receiver as it tried to go into the chamber, thus stopping the carrier and locking piece from going into battery? See how the brass... brass... wait I said, this is M67 Yugo brass cased?  I never tested any brass cased rounds. Doh!


There was also another pic of a steel case round I received (not shown) that threw me off a bit. 


He also sent me this pic of a cut Czech receiver (probably from a kit), asking me why on the bottom corners were not relieved on the rail protrusions in front of the slot where the locking piece drops in.  But I really couldn't see the relieved corners in the pic and I was unaware of this shortcoming(?) of the CAI receiver design.

(test and marks mine)



Later we did a Skype video call and he showed me what he was referring to.  I compared an OOW receiver (which feeds 100%) and the corners were there.  Finally a grabbed a Czech Sa. Vz.58 and low and behold there it was (or wasn't).  The corners are removed on the Sa. Vzor58, aiding in the case feeding into the chamber from either side of the mag stack.  The brass was getting hung up on those corners. We agreed that he should try relieving the corners, which he carefully completed with a proper file and stone. 


It's been nothing but blue skies and high times since.


So if you ever have feed issues, esp. with Yugo M67 brass cases, consider taking down those corners. I still personally think that you could sling-shot charge that first steel case round into the chamber and the rest would follow on firing, but perhaps everyone with a vz2008 might check their spent cases to see if those rail corners are scratching into the case.  If they are, brass cased rounds may become an issue with some guns. I also think the vz2008 should (could, might, maybe) wear in over time with steel cases.


Here are pics (looking up into the mag well) of a CSA Sa.Vz.58 vs. a CAI vz2008:










There may be other posts on this topic, but I didn't find any.  This older post talks about feed ramp mostly http://www.czfirearms.us/index.php?topic=26300.msg139288#msg139288.   If this post is redundant, or if I fell asleep during a Forced March gunsmith class (he may have covered this), then please accept my apologies.


Anyone else have this issue and performed this fix?
« Last Edit: July 02, 2016, 02:04:39 AM by CitizenPete »
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The post above is opinion, and I am probably totally wrong, so please pardon me if I offend anyone in any way. I am speaking only for myself and just sharing my thoughts, not trying to start an argument with anyone, and if you disagree with anything I have said, I concede your correct.

Offline TJNewton

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #1 on: March 10, 2016, 07:14:34 PM »
I've read almost every VZ58 post on this and other sites twice and have never heard this issue brought up.  Great catch!  I haven't had any feeding problems, but neither have I shot any brass case ammo.  Your post may save me or someone else a tremendous amount of time in the future.  Good job and thanks very much!

P.S.  I did get an "Old Yeller" squeeze to my heart when you mentioned that you have to sell your stuff.  I hope that you get better and that someday you can rebuild your collection.

Offline Tempestv

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #2 on: March 10, 2016, 08:14:29 PM »
I just looked at my vz2008, it's got the sharp corners as well. I've never had problems, but I've also never shot brass cased ammo. I might have to buy a box and try it.

Offline RSR

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #3 on: March 10, 2016, 09:09:08 PM »
Interesting.  First I've heard of it.  Good work by both of you!

Actually, should probably sticky this or add to one of the info stickies...  Filing that down shouldn't be an issue -- though a receiver  insert/file guide would be really cool for perfectionists...

And sorry to hear about the collection being pared back.  No doubt it's a bear...
« Last Edit: March 10, 2016, 09:12:10 PM by RSR »

Offline TJNewton

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #4 on: March 11, 2016, 12:00:44 PM »
CitizenPete --
 
You mentioned in your post that the buyer relieved the corners with a proper file and stone.  What is the process for that?  I imagine it starts with rough abrasion and then smoothed down, but I'm ignorant as to what kind of file and stone needs to be used and how it's done.  Can you summarize how it's done, and perhaps what grades of file and stone?

Thanks!

Offline jwc007

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #5 on: March 11, 2016, 01:28:27 PM »
Interesting.  First I've heard of it.  Good work by both of you!

Actually, should probably sticky this or add to one of the info stickies... 

Done!

My Vz2008 receiver does not have the bevels.  I've NEVER shot any brass cased Ammunition through my Vz2008, so I would not know if it has this issue or not.

I do have some brass cased 7.62x39mm by Fiocchi and Lapua, and used to shoot that in my late traded off Ruger Mini-30.
I generally avoid Yugo surplus 7.62x39mm which is corrosive.
"Easy is the path to wisdom for those not blinded by ego." - Yoda


For all of those killed by a 9mm: "Get up! You are not dead! You were shot with a useless cartridge!"

Offline RSR

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #6 on: March 11, 2016, 01:32:28 PM »
I have taken a file to a Century golani receiver before -- started w/ a standard file and finished w/ sandpaper.  Sandpaper is same as you'd use to polish feed ramps, etc.   I like to finish w/ flitz paste on any super fine polishing, but isn't critical if you go high enough on your sandpaper grit...

These receivers are hardened and the space tight so probably precision diamond files is best place to start.

I would be curious on/really appreciate measurements -- it'd probably be doable to tape/paint off the section needing relieved to keep it easy to keep track of material removed/ensure properly oriented filing...
That is -- length from relieved corner to stop of relief to both sides as square (length before relief of that edge, not length of longer relieved edge if that makes sense), and depth of the apex of that corner relief (how far down/up that corner relief is).

Offline gwvt

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #7 on: March 11, 2016, 05:12:23 PM »
This is definitely interesting - thanks for posting it. I haven't tried brass cased ammo in mine but I guess I'll have to pick up a box when I can just to see what happens. I suppose this should be added to my list of eventual mods.

Also sorry to hear about you having to scale back.

Offline CitizenPete

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #8 on: March 14, 2016, 11:02:09 AM »
CitizenPete --
 
You mentioned in your post that the buyer relieved the corners with a proper file and stone.  What is the process for that?  I imagine it starts with rough abrasion and then smoothed down, but I'm ignorant as to what kind of file and stone needs to be used and how it's done.  Can you summarize how it's done, and perhaps what grades of file and stone?

Thanks!


After I laid a small file on the corners for reference, I realized just how tight that work must be.  A very small file would be required. I guess if I had a problem with a vz2008 I personally would start by relieving those corners just a little bit with a fine dremel bit (my answer for everything).  I would test fire and repeat as necessary. After the feed issue was resolved (on the bench) I would be following up with lots of hand work with a small stone and fine sand paper/emery/polish smooth.  I dont know that the entire corner would necessarily have to be removed -- testing the gun as material is removed would certainly provide the empirical feedback data to confirm that.  Your guess is as good as mine at this point. 


I will send an email to the buyer who made the modifications and invite him to the forum.  Perhaps he could share his work with pics on this thread. After spending online and phone time with him, I think there is a good chance he would do that as he appears to be a real stand up guy.  He has a another really interesting and nice looking Czech flare rifle in his collection that I believe you guys would be interested in seeing.  It looks like some parts are straight off a vz.58.
« Last Edit: March 14, 2016, 11:14:30 AM by CitizenPete »
CP

The post above is opinion, and I am probably totally wrong, so please pardon me if I offend anyone in any way. I am speaking only for myself and just sharing my thoughts, not trying to start an argument with anyone, and if you disagree with anything I have said, I concede your correct.

Offline RSR

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #9 on: March 16, 2016, 02:09:46 PM »
Good read and pic gallery on right sidebar: http://www.smallarmsreview.com/display.article.cfm?idarticles=1026

I didn't realize that the Ronin grip was anything more than an elongated VZ58 one...

Offline JohnEd

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #10 on: April 26, 2016, 12:38:37 AM »
I checked my D Tech with my Mark I Mod 0 eyeball and i have sharp corners.  Must not be that sharp as i have fed 6 or 8 20 round boxes of brass ammo through that Bad Girl and never a hickup.  The gun impresses me.  Maybe my "corners" are not surgical sharp.  My Rapid Fire Receivers have the same corners and they are much sharper but only steel cases have gone through them.  I will modify all three of my guns to avoid future problems.

Pete,

Thank you for getting this word out.  We have a great gun and any and all problems should be worked through.  So many people owe you a vote of thanks for all the times you have done things like this for us all.

John

Offline StevenJ61

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #11 on: June 26, 2016, 08:44:52 PM »
I guess it depends on the rifle. I have a Century VZ2008 and the vast majority of my 7.62 stash is Yugo M67 brass cased ammo! It's the exact same ammo pictured in the rifle in the first post. I've had issues sometimes with the first round going into battery. It's usually because I didn't pull the bolt far enough back. After the first round though, no issues.

Offline TJNewton

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Re: Interesting Feed / Ramp Issue and Receiver Design Observation
« Reply #12 on: June 26, 2016, 11:54:39 PM »
I guess it depends on the rifle. I have a Century VZ2008 and the vast majority of my 7.62 stash is Yugo M67 brass cased ammo! It's the exact same ammo pictured in the rifle in the first post. I've had issues sometimes with the first round going into battery. It's usually because I didn't pull the bolt far enough back. After the first round though, no issues.

That's typical even with steel case ammo and has happened to me as well.  The rifle doesn't like it when the bolt isn't pulled all the way back or when it's ridden forward.  I don't necessarily see it as a flaw as while some guns will chamber with the bolt or slide eased forward, it's a bad habit and invites jams and problems.  All firearms should be racked with authority.

 

anything