Author Topic: CZ trigger job - Over travel fix  (Read 4152 times)

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Offline greyling22

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Re: CZ trigger job - Over travel fix
« Reply #30 on: July 21, 2017, 02:30:35 AM »
So I'm cheap and have a dremel tool and some calipers, so I cut apart a federal 308 case I found at the range. The neck measured .015 and the base .035. I haven't tried them in the cz yet, but with a little jbweld under them they might be pretty close to perfect. And who knows, someone might find another case that works better.


« Last Edit: July 21, 2017, 10:34:05 AM by greyling22 »

Offline DanT

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Re: CZ trigger job - Over travel fix
« Reply #31 on: July 21, 2017, 09:41:04 AM »
I have noticed that my local Ace Hardware is carrying the K&S engineering brass stock much cheaper than what I got off of Amazon.  A 12 inch strip is roughly $1 to $2.

The 0.016" stock is hard to cut with scissors, but it can be done.  It then needs to be tapped flat with a hammer.  The thicker stuff is harder to cut, but a lot of folks have access to a dremel tool with a cut off wheel.

Stealing the brass from a used shell casing certainly represents the "DIY" spirit!

- DanT  Phoenix, AZ

Offline jameslovesjammie

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Re: CZ trigger job - Over travel fix
« Reply #32 on: July 21, 2017, 11:19:27 AM »
So I'm cheap and have a dremel tool and some calipers, so I cut apart a federal 308 case I found at the range.

You and I think alike!  I did the EXACT same thing last week!  I have yet to JB Weld them on yet, as I had my first USPSA match with the gun and wanted to make sure it was running like a top.  Have to get it cleaned up and welded in!

Offline John A.

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Re: CZ trigger job - Over travel fix
« Reply #33 on: July 21, 2017, 11:37:26 AM »
Ok, you guys are really tempting me now.  I ran across some federal 308 brass in my pile just the other day.

I've been fighting off the urge for a while, but don't know how much longer I can hold out.
When people ignorant of guns make gun laws, you end up with ignorant gun laws.

Offline lorazepam

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Re: CZ trigger job - Over travel fix
« Reply #34 on: July 21, 2017, 05:18:35 PM »
I might have to try some .40 brass I picked up but don't reload.

Offline greyling22

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Re: CZ trigger job - Over travel fix
« Reply #35 on: July 28, 2017, 11:04:06 PM »
I jb welded in my trigger shims I cut from the 308 case yesterday and assembled today. What an improvement! Not perfect, but good enough. The disconnector shim was perfect. The thicker pretravel shim could have stood to be a little thicker as I still have some creep, and I did have to file the back of the sear housing down to clear the safety. Thanks to Dan T for posting all his guidance. if you can afford it, get the czcustom trigger, for the rest of us, shims for the win! I went from the worse trigger have have ever felt to a trigger that feels a little better than a good polished AR milspec trigger with the set screw in place to take out some of the creep.

couple thoughts:
1- when filing down the sear for the safety, don't forget the shimmed sear will be at an angle, not flat, so you should file at a but of a rearward sloping angle if you are filing on a flat surface.
2-my narrower HBI trigger return spring was sliding off to the drivers side of the bent tip of the firing pin disconnect and dragging on the side of the trigger pack. So once again I busted out the cutting wheel on the dremel and cut a small notch in the leg where the spring will now ride instead of wandering off to the side. That sounds a little confusing to me, so I'm attaching a picture. The yellow line was where my spring leg had wandered off to, and the red line denotes where I notched on the underside of my metal finger thing to keep the spring in that location. It works great so far. (not my trigger pack, borrowed image from google and tweaked with ms paint)


Offline DanT

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Re: CZ trigger job - Over travel fix
« Reply #36 on: July 29, 2017, 01:42:37 PM »
The geometry of the disconnector and the trigger is such that I really could not go any farther than a 0.032" "pre-travel" adjustment.

The problem is that there is a minimum disconnector "bite" needed in order to avoid un-intentional double and triple shots at the range.



This is not a very good picture, but with the over travel shim in place, the disconnector needs to be able to grab about half the rear hammer shelf as shown.  Now if the disconnector is biting this much of the rear hammer shelf, it is going to need some "forward trigger travel" to let go.  The amount of trigger travel required to "left go" is about how much travel you have left over with a 0.032" shim.

In other words, if you were to add more than 0.032" of pre-travel shim, you would have to reduce the disconnector "bite" on the rear hammer shelf and that in turn would left to a much higher chance of accidental double and triple shots.

I think there was another 0.007" of pre-travel before the trigger fires.  One further point: Even if you could increase the pre-travel shim more than 0.032", you are making it harder and harder on the safety to stop the rifle from firing as you shrink the distance between pre-travel and firing to be closer and closer together. 

However, at least for me that was not really even an option.  I don't want doubles and triples.  You do get strange looks at the range when that happens.  With 0.032" pre-travel and 0.013" over-travel removed, the trigger feels way better than it did before as you have removed 0.045" (0.032" + 0.013") out of ~ 0.052" (0.032 pre-travel + 0.013" over-travel + 0.007 distance-to fire remaining) possible.

The impossibly long trigger pull has now become very reasonable. Even just doing 0.016" pre-travel and 0.013" over travel helps a lot and has the advantage of perhaps no change to the safety.

- DanT  Phoenix, AZ

Offline Eatstone

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Re: CZ trigger job - Over travel fix
« Reply #37 on: January 05, 2018, 08:31:57 PM »
Thanks for the write up DanT. I couldn't source brass shim stock locally. I bought some cheap feeler gauges and cut them up. Works perfectly!

Offline Earl Keese

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Re: CZ trigger job - Over travel fix
« Reply #38 on: January 18, 2018, 08:44:31 PM »
DanT, just wanted to post a quick thank you here. After reading your posts about your shims a few times, I went ahead and gave it a try. It worked as I'd hoped so I removed the shims and added some metal with a mig welder and filed everything to fit. Had it out to the range today and I'm still smiling. Right at 4lbs with about 1/8" of total travel. Turned out better than I'd hoped for, thank you sir!

Offline DanT

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Re: CZ trigger job - Over travel fix
« Reply #39 on: January 19, 2018, 03:58:31 PM »
I am glad that it is working well for everyone.  I have done a couple of these triggers, all with good improvements.

The trigger cannot be made "hair trigger" because the disconnect has to have a "half rear hammer shelf bite", and the trigger must be able to move forward just enough to undo this bite.  However, that is a lot less movement than before the fix.

I also like a softer trigger pull. Polishing the trigger parts also allows for a softer trigger spring that is still reliable for the trigger reset.  I run with about a 3 lbs trigger pull using a custom trigger spring.  As I have said, these springs are dead simple to make and play with.  0.039" music wire is pretty cheap on Amazon.

- DanT  Phoenix, AZ

Offline Destructo6

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Re: CZ trigger job - Over travel fix
« Reply #40 on: February 01, 2018, 10:12:59 AM »
I followed these instructions, more or less, and glued in a .016" thick brass shim fore and aft of the trigger opening.

The brass was found at a local ACE hardware in their sheetmetal section. I had to buy a 1" x 36" section, because that was what they had in that thickness. I paid around #3, IIRC. I really only needed about an inch of the material to do the 3 trigger housing I have.

Using a Dremel, I cut the brass into strips that would fit fore/aft of the trigger cutout. Precision was not really necessary. I did sand the burrs off to allow the shim to lay flat.

Again, because it's what they had, I used Loctite's Epoxy Weld to glue the shims in place.

I dropped the trigger housing upside down on a 1"x2"  bit of wood (protected from the glue with painter's tape) and clamped in a vise for a hour.

After an hour, they came out of the vise and was able to trim excess epoxy from the trigger opening (or anywhere else that it squeezed out) with a razor knife, then let sit for 24hrs.

Some work with a file was necessary to remove excess epoxy and slightly slipped shim from the trigger openings and 1 trigger housing's rearward  (pre-travel) shim had to be filed to allow the safety to engage.

The work probably took no longer than what was needed to write this post. Obviously, I'm discounting the epoxy's drying time.

The results are very good. The total trigger travel has been reduced to about 1/8" as measured at the bottom leading edge of the stock trigger. Takeup, overtravel, and reset are drastically reduced.

With this simple mod, HBi springs, and a light polish, my trigger measures 4lbs, 7oz on average.

It's not in the same class as a Hyperfire or Geissele, but it is light years better than how it started.

I test fired it on Friday and had no problems. May shoot it in a couple of 3-gun stages on Sunday.

Thanks for the Tutoria, DanT.