Scorpion failure to feed issue - any idea why?

[Dan_69GTX]

This ONLY has happenes with an extended magazine.  It has yet to happen with the Manticore or Factory mags.

The extended mags that I have are as follows
 - 2 30 round mags tied together with the TACCOM3G splice
           https://taccom3g.com/product/cz-scorpion-magazine-coupler/)
 - the CZ custom 20 round extension added to a 30 round mag
           https://czcustom.com/cz-scorpion-evo-3-s1/cz-scorpion-evo-mag-ext-red.html?___SID=U)

This happens with any ammo I have tried - 115-147 grain, HP, RN, etc.  Happens once or twice a magazine.  Typically when the mag is between 3/4 full and full, never at the same place.  Every now and then the mag will run clean.

The nose of the bullet ends up above the chamber.  The bolt then slams into the base of the cartridge seriously denting the nose of the bullet.

Any recommendation would be appreciated. 

[Asylum9]

I read about a similar issue when cz custom first came out with there extension a year or so ago. It was posted in the forums here. I believe it came down to a spring issue. Sorry I can't be more help, might help you narrow down the search.

[Asylum9]

This is what I was referring to.
https://czfirearms.us/index.php?topic=85116.msg632967#msg632967

And

https://czfirearms.us/index.php?topic=84857.msg630321#msg630321

[Mr.E.G.]

I don't have any special knowledge about this issue in particular. But I also think there's an apparent answer. A magazine needs a strong enough spring to push the next round into place before the bolt pushes it into battery. So, what we're probably dealing with here is a spring that isn't strong enough to push the round into place quickly enough, so it gets pinched by the bolt. In short, the mag springs are either too weak or encountering some friction or mechanical interference. I would take one of the mags apart, stretch the spring, and then put it back in. See if that helps.

[Dan_69GTX]

BINGO!!!

Mr. E.G. is correct!   This morning I took the spring from CZ custom's extended mag and used it and a factory spring in the taccom coupled mags and it worked fine but could only fit 55 rounds in instead of 60.

For the CZ Custom extended mag I used the spring that came with it, and put a 2" spacer in to compress the spring and it worked.

So, now I know WHY what happened!   Thanks so much for your recommendation!

[akuser47]

So glad you found a fix as I had no idea what was your issue in this case. Thanks for updating your post.

[bravo5two]

BINGO!!!

Mr. E.G. is correct!   This morning I took the spring from CZ custom's extended mag and used it and a factory spring in the taccom coupled mags and it worked fine but could only fit 55 rounds in instead of 60.

For the CZ Custom extended mag I used the spring that came with it, and put a 2" spacer in to compress the spring and it worked.

So, now I know WHY what happened!   Thanks so much for your recommendation!

Oh good you found the culprit!

I am using the Taccom splice too, but only with one 20 + one 30, no issues but probably because the 20 rds mag spring is just about the same as the 30 so this combination worked without having to resort to a longer/+ power spring.

[Dan_69GTX]

UPDATE:

Apparently that worked for a few tests at home.  At the competition I had another Failure To Feed.   I gave up on the mag for the day.  at home I tried again, with various ammo - all had the issue.   So....

I give up on the coupler!

I have now spent more trying to resolve the issue than the CZ Custom extended mag costs - and I have that working fine.

Dan

[Dan_69GTX]

John, good point!  Something I have considered.  However, in the PCC competition I'm in, most folks are using a 50 or 60 round mag.   Just the time required to swap mags puts me out of the top 10 due to how close the times are.  So, I need a good reliable 50+ round mag so that I can be competitive.  I was just trying to be cheap and go with the $30 3D printed item instead of another $75 CZ custom unit.  I was stupid to try it.  Last competition I was  #17 due to the mag not feeding would have easily been in the top 10 if it hadn't jammed.  Oh well..... live and learn.

[Dan_69GTX]

Thank!

No, they don't allow machine guns.  Would be cool if they did - as long as they were in a class that I didn't have to compete with! 

I see there is a 50 round drum for the Scorpion.  Might need to try that, but it is a $160 and I'd rather spend that money on a case feeder for my reloading press. (or more bullets, powder, etc).

[brisix]

IMO the issue is being caused by the plastic mag lips being spread apart due to the pressure from a fully loaded extended mag.   I only had issues with the first 5 rounds.  Also over time you would see a diagonal stretch mark at the inside rear corner of the feed lips.  Eventual it would crack in the same spot. I resolved the problem by switching to the Maniticore Arms mags with metal feed lips.  So far the metal feed lips are able to with stand the pressure of a fully loaded extended mag and have zero failure to feeds.

[Dan_69GTX]

Well, considering I am using the manticore mags, I don?t think the plastic lip is the issue.

I have tried all sorts of combinations of magazines and springs.

[Manticore_Arms]

Stick mags simply start running into a smaller amd smaller function envelope of high vs low acceptable spring pressure mag lip friction, and a few other factors once you get past about 30-40rounds.

On top of that the Scorpion EVO has a very fast and short bolt cycle time due to the relatively short receiver.

Drums can use a constabt pressure coil spring which in thery can make larger capacities feasible.

Sven
Manticore Arms

[Dan_69GTX]

Stick mags simply start running into a smaller amd smaller function envelope of high vs low acceptable spring pressure mag lip friction, and a few other factors once you get past about 30-40rounds.

On top of that the Scorpion EVO has a very fast and short bolt cycle time due to the relatively short receiver.

Drums can use a constabt pressure coil spring which in thery can make larger capacities feasible.

Sven
Manticore Arms

Sven, Thanks - that is good information to know!

Please make sure you understand that I am NOT complaining about your mags or that they are contributing to this issue.  Your mags have worked just fine (when I don't dork with them).

Dan