Author Topic: Fine Tuning Plastic Magazines (Tapco)  (Read 24348 times)

0 Members and 2 Guests are viewing this topic.

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Fine Tuning Plastic Magazines (Tapco)
« on: February 27, 2013, 01:11:59 PM »
Fine tuning Tapco polymer magazines.

Once you are sure that the mag is fitting into your stock without binding and it is still cramming shells up against the end of the barrel, you may have to change the feed angle of the magazine lips to elevate the round.

The widest point of the chamber hole is where you want the bullet point to hit.  This has the best chance of going into the chamber without jamming.
Elevating the entry angle keeps the bullet off the 8 to 4 area. 

The curved feed lips of the mag will also slightly angle the round toward the chamber centerline if the angle is tipped up a little.
Up and in is what you want.

If your mag jams when full, try it with 10 rounds, then just 2 or 3 rounds. Some just don't want to work well when full. Some may feed from the left stack, some from the right.  Only fix what is broke. Stretching doesn't do any good. No matter what all those emails say.

Start with just a couple rounds in the mag and some 400 to 600 emery paper.  Take just a little material from the front of the lip at a time. Slide the emery paper fore and aft with the bullet in place. You want to concentrate on the forward half of the lip but you want to end up with a smooth taper.
Clean up the area and try to manually feed the rounds.

I TAKE THE TRIGGER GROUP OUT, REMOVE THE HAMMER AND SPRING, THEN PUT THE TRIGGER GROUP BACK IN WHEN PLAYING WITH LIVE ROUNDS. ALWAYS POINT THE MUZZLE IN A SAFE DIRECTION. 
Let the bolt fly and see if there is any improvement, noting which side works best. 
This has fixed the feeding issues on every one I have tried. 
I also spray a little dry lube inside the mags to help.
 
This is where to sand.






You can see how little material was removed.



After sanding, the round heads straight for the chamber. Even a Hollow Point.

« Last Edit: February 27, 2013, 11:55:00 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

damarble

  • Board Supporter
  • SKS Sniper
  • *****
  • Posts: 555
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #1 on: February 27, 2013, 01:15:36 PM »
Thanks for this. Pics aren't working for me though.

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #2 on: February 27, 2013, 01:16:59 PM »
Whoops.  Album is now public. Better?

In addition to guiding the round into the chamber the feed lip also functions as a curved spring over the round to hold it in place.
Here's one of mine after sanding.
Notice the taper in the feed lip, and the gap between mag and receiver (oh well).






and mag is all the way forward, and up as far as it will go without modification.
If it doesn't fit all the way forward the rear will not go up all the way and the BHO can drag on the mag body.
This is an important area to check.
« Last Edit: March 18, 2013, 01:38:15 AM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

damarble

  • Board Supporter
  • SKS Sniper
  • *****
  • Posts: 555
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #3 on: February 27, 2013, 02:50:59 PM »
Good to go. Mine don't feed reliably and  I need to do this.

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #4 on: February 28, 2013, 05:17:24 PM »
I sanded one more Tapco mag that seemed to jam when manually sending rounds home.
If you look close at the pictures you can see some milling marks in the receiver for reference showing the round sits angled up just a little more. 

This seems to work for me, as none of the 20 rounds jammed when manually fed.

First the unsanded mag


and now after sanding
« Last Edit: March 06, 2013, 09:57:09 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

quadster

  • SKS Expert
  • ****
  • Posts: 443
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #5 on: February 28, 2013, 08:50:32 PM »
Very good info and pics. Thank you. Was playing around last night a bit and sanded a little bit off the new tapco before even cycling rounds to try it out.

 Removed firing pin, loaded 20 in and would not feed the first round....hmmmm... got to thinking about an old Marlin .22 bolt action i have. On that, i have to be pretty aggresive with the bolt every time and it will cycle perfect. So tried that with the sks and chambered and ejected all 20(half wolf fmj 124 and half demilled soft points(?)!!  Maybe i didnt even have to sand at all? Range this weekend  to check for sure.
Thanks

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #6 on: February 28, 2013, 10:37:05 PM »
Just like when the gas sends the bolt back, let her fly to strip a round. 


EDIT:
A similar issue is being discussed in another thread and would be good reading for anyone having issues with Tapco mags. 
http://www.sksboards.com/smf/index.php?topic=115695.0
Minimize any modifications you do and make frequent checks as you go. 

Be careful when chambering live rounds.  I take the hammer out of my trigger group (I also have a spring loaded firing pin). Some people remove the firing pin. and ALWAYS point the weapon in a safe direction.
« Last Edit: March 02, 2013, 02:19:50 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #7 on: March 01, 2013, 01:03:16 PM »
If your Tapco mag is sitting all the way forward in the front trunnion, and up as high as you can get it, but you still have jams, try tapering the feed lips (just a little).
Take out your firing pin or the hammer and spring before playing with live rounds.  It's always best to pull the bolt back and 'let-er-fly' but notice how the rounds feed in this little video clip;
DUMMY HP ROUNDS USED
http://www.youtube.com/watch?v=6IMCkom7lfk
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #8 on: March 15, 2013, 08:03:05 PM »
Did a range test today.  Took 4 modified and one unmodified mag. 
Ran about 160 rounds through the SKS with one failure to feed (unmodified mag).
The sanded ones did great. 

The wife and I shot about 550 rounds total of 54r, x39, 9mm, .223, and .357 (I'm the old one)
Guns be a soakin, nap time :)

« Last Edit: March 17, 2013, 06:00:01 AM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Leverpuller

  • SKS Marksman
  • ***
  • Posts: 143
  • Wait!....How did I end up here!
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #9 on: March 15, 2013, 08:41:50 PM »
Excellent thread, great pics, very informative!.... I shot 40 rounds thru my Yugo today...I have two Tapco 20rd mags. They feed great with no jams , but the problem I am having is, as you stated, when filled to capacity (20rds) the internal spring seems to get stuck to the bottom of the mag. I load 10-15rds I have no problems. Maybe they just need a break in period. In any case tomorrow I am going to try and findsome dry lube and see if that helps. Thanks for the info.
God grants us our Rights.....We The People grant the government it's Rights.

BillyBang

  • What did you expect?
  • Global Moderator
  • SKS Guru
  • *****
  • Posts: 10369
  • Si vis pacem, para bellum
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #10 on: March 15, 2013, 08:53:21 PM »
If it's ok with you RV,
we'll put this up as a sticky for a while.
Americans love solutions to nonexistent problems. --- Danjal

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #11 on: March 15, 2013, 08:56:53 PM »
Not a problem.  It doesn't cover everything with mag function but it worked for me today. 
I don't know if I mentioned this, but I have done the drop free mod on mine for safety reasons also.

The only malfunction I had the whole day was that one round that didn't feed into the chamber (right side) second shot, so that mag got retired for the day.  It's now been sanded, as will the next few that I get.  Here are a couple of daylight pictures of the sanding process and taper.  Glued the sandpaper to a spent round and a tube for a handle.  I also smoothed and deburred the rear of the mag body where it rides against/or close to the BHO. 
I also take each mag apart and deburr edges on the follower. 



« Last Edit: March 17, 2013, 05:48:01 AM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #12 on: March 16, 2013, 10:37:02 PM »
In this thread I showed where tapering the feed lips could elevate the rounds and point them more toward the center of the chamber. 

In one of the other threads, member 'greatguns' (I think) pointed out that the front of the mag needs to sit as far forward as possible.  This allows the triangle tab on the rear of the mag body to float up higher, raising the rounds.  There was even an example of the trunnion on one rifle not being cut deep enough to allow the mag to fit all the way forward.  This can also be the cause for BHO (Bolt Hold Open) malfunctions with the mag sitting too far back.  The rear of the mag will not go up if it can not sit far enough forward.  You have to take the action out of the stock to see how the mag fits in the front.

Now the third area to fine tune.  The magazine release.  I bought an extra mag release and one of the plastic extended releases just in case I screwed up something.  Well, they came in today so out come the hammer and needle files :)

In the first picture below you can see where I peened the lip of the mag catch into a slight circular shape, cut a piece of 10 ga. copper wire and soldered the wire to the mag catch (pic 2). 

In pics 3 and 4 you can see it's too tight for the magazine to be held properly.  You can also see that the plastic extended mag release is not going to help with magazine fit.
 
The last 2 pics show fit after some work with the needle files.  The mag release now holds the triangle magazine tab up a little higher almost touching the receiver at the top. 
I filed to allow a smooth fit, touched up the bluing.

Since we are only messing with a cheap easily replaced part the risk of damage is low. 







Now it fits, just a little more with the file.


Now all I have to do is smooth and blend a little, touch up the bluing and a dab of black on the copper.



« Last Edit: March 18, 2013, 04:50:49 AM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Rocketvapor

  • Board Supporter
  • SKS Guru
  • *****
  • Posts: 15076
  • awarded title of SIR ARSE
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #13 on: March 16, 2013, 10:52:56 PM »
With all the 'Tuning' completed, here's the difference in the angle/elevation of a round in the mag.
The Tapco mag sits all the way forward, the rear is up as far as it can go, and the mag lips are tapered to elevate the rounds even more.


Before



After



(OK, so I didn't get the camera angle the same)

After you get your Tapco 20 rounders working like they should maybe consider working over the trigger group for proper sear engagement and doing the drop free modification to your bolt.  If you're going to shoot your collectable rifle, why not make it as safe as possible?

« Last Edit: March 17, 2013, 05:54:53 AM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

quadster

  • SKS Expert
  • ****
  • Posts: 443
Re: Fine Tuning Plastic Magazines (Tapco)
« Reply #14 on: March 17, 2013, 11:22:52 PM »
Very nice write up. Was out in the the garage a bit today after doing oil changes and brakes and found a little time too play also.. got rid of the epoxy..