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Zbroia Kozak 177 arrived today

I took some measurements and did some calculations, and here is what I came up with:

Original spring is 1.6 inches long, has 0.043 inch wire diameter and 0.26 inch outer diameter.

I've used this calculator https://www.acxesspring.com/spring-calculator.html to calculate spring constant of 32 lb/in

In my 177 12 fpe set up original spring compressed 0.45 inches, which produces 14.4 pounds of energy to the hammer.

Back to the calculator with my smaller 0.037 wire same outer diameter and length spring will give me 16lb/in constant.

My second spring will be shorter 1.2 inch spring with 9 coils and 0.32 inch outer diameter. end cap measure 0.388 inches and has plenty of space to support this second spring.

According to calculator second spring constant will be 13.1 lb/in. Combined constant will be 29.1 lb/in of two springs and I will need to adjust them to get 12fpe power output (about .5 inches compression). Now will try to make these springs.

df8499de30d1cf6074457968f6d2b57e.jpg

this is original cap inside end cap adjuster
b17590b3eb9ca284af6d68d5876435c3.jpg

ccb6633fd5535b34610ca7361916252f.jpg

spring guide back when cocked.
 
"jarmstrong"shutik, I am wondering how you plan on removing the spring guide from the hammer
I have a PDF fron Zbroia for putting a vent hole in the space in front of the hammer, to reduce hammer bounce
I don't know how to copy it to this forum, but can email it to you but I have as yet figured out how to message you direct

You were right, need to remove guide and modify it, because bigger spring does not fit further down. Thanks for the diagram.

Here are my replacement springs:

0cd986b928234008e6a77cd97b38618f.jpg


Here is close up diagram of the guide https://drive.google.com/open?id=0Bx1ozfIjB-dSaGI5eEFOeHBoMWtnY3hrZXROTVVRR1VKSlpB
 
"RAMJET66" My Zbroia kozak 22 cal  stopped indexing the mag , about 600 shots thru the gun, it just quit working tonite, I can see the little arm move upwards when cocking the gun with the mag out , not sure what happened..

I think the arm bends out. If you go to the TAG forum a guy shows pics of his and the fix I believe said this is a weak spot


Edit to add link-

http://talonairgun.com/forum/viewtopic.php?f=37&t=37388&start=60#p386187
 
there is not an o-ring on the valve stem to keep the air ( when firing the rifle) from pushing the hammer back, the hammer them hits the little pin that actuates the magazine advance.
when the rifle is ready to fired ,the magazine advance linkage is held solid, so when the hammer bounces back and hits the pin hard, something will break.
Zbroia's fix is to drill a hole in the trigger linkage area to vent the excess air from pushing on the hammer
shutik has a copy of this pdf, mayby he will post it or you can message me and I will forward it to you
it shows location and size to drill
 
"BigTinBoat"
"RAMJET66" My Zbroia kozak 22 cal  stopped indexing the mag , about 600 shots thru the gun, it just quit working tonite, I can see the little arm move upwards when cocking the gun with the mag out , not sure what happened..

I think the arm bends out. If you go to the TAG forum a guy shows pics of his and the fix I believe said this is a weak spot
Edit to add link-
http://talonairgun.com/forum/viewtopic.php?f=37&t=37388&start=60#p386187........thanks BigTin I appreciate it..

 
"jarmstrong"there is not an o-ring on the valve stem to keep the air ( when firing the rifle) from pushing the hammer back, the hammer them hits the little pin that actuates the magazine advance.
when the rifle is ready to fired ,the magazine advance linkage is held solid, so when the hammer bounces back and hits the pin hard, something will break.
Zbroia's fix is to drill a hole in the trigger linkage area to vent the excess air from pushing on the hammer
shutik has a copy of this pdf, mayby he will post it or you can message me and I will forward it to you
it shows location and size to drill.......thanks Jarmstrong, I appreciate the help ..

 
 I have broken both mag advance pieces in the past
I have drilled the vent hole, as of yet have NO failures
no bent arms, no broken pins after 300 shots
knock on wood
But I can hear more noise in the trigger area,
I also installed a Donnyfl 1/2-20 x 1/2-20 male to male threaded adaptor
and added a LDC much quieter. got a David Furr shorty on its way to replace the no name cheapie LDC
Had a friend with a lathe drill and tap it. I would not try it with a drill press.
to hard to get it perfectly aligned with a drill press, needs to be perfect to prevent pellet clipping
I am all smiles now
 
I removed the stock yesterday, to straighten the cocking lever, which is only a very temporary fix , it is very thin , I hope the new ones when they get here, are improved .. anyway I decided to turn the H/S tension down, as it is shootin close to 900 w Jsb 18 .34's so I marked it with a sharpie, & backed it out 2 full turns, & the stock would not go back on with the mounting holes, ( with the H/s tensioner backed out , it was hitting the the wood )so I got a dremel & started removing the wood for the back screw hole to line up, but there is not a lot that can be removed, as it is close to the brass thread , so I ended up turning the H/S back in a 1/2 turn to even get the stock back on , so it l;ooks like I am stuck with the H/S setting that still uses way too much air, but I still like the gun , will like it even better if & when I receive the New cocking lever..
 
"RAMJET66"I removed the stock yesterday, to straighten the cocking lever, which is only a very temporary fix , it is very thin , I hope the new ones when they get here, are improved .. anyway I decided to turn the H/S tension down, as it is shootin close to 900 w Jsb 18 .34's so I marked it with a sharpie, & backed it out 2 full turns, & the stock would not go back on with the mounting holes, ( with the H/s tensioner backed out , it was hitting the the wood )so I got a dremel & started removing the wood for the back screw hole to line up, but there is not a lot that can be removed, as it is close to the brass thread , so I ended up turning the H/S back in a 1/2 turn to even get the stock back on , so it l;ooks like I am stuck with the H/S setting that still uses way too much air, but I still like the gun , will like it even better if & when I receive the New cocking lever..

you should be able to just take a coil off the spring and turn the adjuster back in a bit.
 
the vent hole modification is working-put another 500 rounds through it and mag advance system is still working
this is the longest my rifle has worked since I received it. Happy,Happy,Happy
mine is the 22 cal 40 joule compact reg is set to 115 bar and I shorten the hammer spring about 1/4"
shoots 16grain AA 765 fps 60 shots per fill. Could go faster but I wanted it tuned down . great accuracy